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DotRunpeX – demystifying new virtualized .NET injector used in the wild

March 15, 2023
Research by: Jiri  Vinopal.

Highlights:

  • Check Point Research (CPR) provides an in-depth analysis of the dotRunpeX injector and its relation to the older version
  • DotRunpeX is protected by virtualization (a customized version of KoiVM) and obfuscation (ConfuserEx) – both were defeated
  • Investigation shows that dotRunpeX is used in the wild to deliver numerous known malware families
  • Commonly distributed via phishing emails as malicious attachments and websites masquerading as regular program utilities
  • We confirmed and detailed the malicious use of a vulnerable process explorer driver to disable the functionality of Anti-Malware services
  • CPR introduces several PoC techniques that were approved to be effective for reverse engineering protected or virtualized dotnet code

Introduction

During the past few months, we have been monitoring the dotRunpeX malware, its usage in the wild, and infection vectors related to dozens of campaigns. The monitoring showed that this new dotnet injector is still evolving and in high development. We uncovered several different methods of distribution where in all cases, the dotRunpeX was a part of the second-stage infection. This new threat is used to deliver numerous different malware families, primarily related to stealers, RATs, loaders, and downloaders.

The oldest sample related to the new version of dotRunpeX is dated 2022-10-17. The first public information about this threat is dated 2022-10-26.

The main subject of this research is an in-depth analysis of both versions of the dotRunpeX injector, focusing on interesting techniques, similarities between them, and an introduction to the PoC technique used to analyze a new version of dotRunpeX as it is being delivered virtualized by a customized version of KoiVM .NET protector.

Background & Key Findings

DotRunpeX is a new injector written in .NET using the Process Hollowing technique and used to infect systems with a variety of known malware families. Although this injector is new, there are some connections to its older version sharing some similarities. The name of this injector is based on its version information which is the same for both dotRunpeX versions, consistent across all samples we analyzed and containing ProductName – RunpeX.Stub.Framework.

While we have been monitoring this threat, we spotted a few publicly shared pieces of information, mainly by independent researchers, that were related to the functionality of dotRunpeX but misattributed to a different well-known malware family.

We are aware of a publication about one campaign delivering this threat, but our findings and conclusions based on the report below slightly differ. By monitoring this threat for a few months, we got enough information to differentiate the first-stage loaders from the second stage (dotRunpeX) with no signs of the relation between them. We revealed the connections to its older version, the distribution of numerous malware families, and several different techniques used as a vector of infection.

Among the variety of downloaders and cryptocurrency stealers, we spotted these known malware families delivered by dotRunpeX:

Figure 1: Malware Families Delivered by DotRunpeX

From the timeline perspective, based on the compilation timestamps of dotRunpeX samples that did not appear to be altered, this new threat became popular mainly during November 2022 and January 2023. What could be just an interesting coincidence or just some kind of sign of attackers waiting under the Christmas tree is that we did not see a lot of samples compiled during December 2022.

Figure 2: DotRunpeX Timeline – Compilation Timestamps

Vector of infection

DotRunpeX injector commonly comes as a second stage of the original infection. The typical first stages are very different variants of .NET loaders/downloaders. The first-stage loaders are primarily being delivered via phishing emails as malicious attachments (usually as a part of “.iso”, “.img”, “.zip”, and “.7z”) or via websites masquerading as regular program utilities. Apart from the most common infection vectors, the customers of dotRunpeX are not ashamed to abuse Google Ads or even target other potential attackers via trojanized malware builders.

Example phishing email Transaction Advice 502833272391_RPY - 29/10/2022 delivering the first stage loader as a part of malicious “.7z” attachment that results in loading of dotRunpeX (SHA256: “457cfd6222266941360fdbe36742486ee12419c95f1d7d350243e795de28200e”).

Figure 3: Phishing email “Transaction Advice 502833272391_RPY – 29/10/2022”

Example phishing websites – masquerading regular program utilities (Galaxy Swapper, OBS Studio, Onion Browser, Brave Wallet, LastPass, AnyDesk, MSI Afterburner) and delivering the first stage loaders that result in dotRunpeX infection in a part of the second stage.

Website masquerading as Galaxy Swapper: https://www.galaxyswapper[.]ru/

Figure 4: Google search for the utility Galaxy Swapper leads to “https://www.galaxyswapper[.]ru/”

Download redirects to https://gitlab[.]com/forhost1232/galaxyv19.11.14/-/raw/main/GalaxyV19.11.14.zip.

Figure 5: Download button on “https://www.galaxyswapper[.]ru/” redirects to a trojanized program

Website masquerading as LastPass Password Manager: http://lastpass[.]shop/en/

Figure 6: Website “http://lastpass[.]shop/en/” masquerading as LastPass Password Manager

The fake website of LastPass Password Manager was already down at the time of the investigation. Still, we can confirm that the fake software was downloaded from the “Final URL” https://gitlab[.]com/forhost1232/lastpassinstaller/-/raw/main/LastPassInstaller.zip.

Figure 7: Download button on “http://lastpass[.]shop/en/” redirects to a trojanized program

The GitLab page https://gitlab[.]com/forhost1232 contained dozens of programs trojanized by dotRunpeX malware.

Figure 8: Dozens of trojanized programs on GitLab repository “https://gitlab[.]com/forhost1232”

All of the trojanized programs on the previously mentioned GitLab page contain the main .NET application enlarged with an overlay to avoid scanning with sandboxes very likely.

Figure 9: Examples of trojanized programs served by the GitLab repository “https://gitlab[.]com/forhost1232”

The mentioned .NET applications with overlay are the typical first stages, behaving as dotnet loaders with simple obfuscation. These different variants of loaders use reflection to load the dotRunpeX injector in the second stage. Some of them are very simple, and some are more advanced.

Simple first-stage loader (direct usage of method System.Reflection.Assembly.Load()):

Figure 10: Simple first-stage loader

An example of a more advanced first-stage loader (using AMSI Bypass and DynamicMethod to load and execute the second stage via reflection) can be seen below. The advantage of this kind of advanced loader is that there is no direct reference to System.Reflection.Assembly.Load() method so it could possibly avoid detection of engines relying on static parsing of .NET metadata.

Figure 11: More advanced first-stage loader using AMSI bypass and DynamicMethod

Deobfuscated form of the latter one could be seen in the picture below:

Figure 12: A deobfuscated form of a more advanced first-stage loader

Programmatic way of second-stage extraction (dotRunpeX stage) from these kinds of loaders could be simply implemented using AsmResolver and reflection as shown below.

Figure 13: Extraction of dotRunpeX from first-stage loader using AsmResolver and reflection

Important to note that those examples of phishing websites leading to the GitLab page were related to just one campaign where the dotRunpeX injector was always responsible for injecting Redline malware with C2 – 77.73.134.2.

In addition to the most common vectors of infection mentioned earlier, we observed quite an interesting case of infection vector, where a customer of dotRunpeX was probably bored enough to target ordinary victims and decided to target other potential attackers. Something that is supposed to be a Redline builder Redline_20_2_crack.rar (SHA256: “0e40e504c05c30a7987785996e2542c332100ae7ecf9f67ebe3c24ad2468527c”) was trojanized with a downloader that uses a reflection to load dotRunpeX as a hidden “added feature” of the builder.

Figure 14: Folder structure of trojanized Redline builder

It turned out that during the building process of the Redline, configured to your needs, one will also get another Redline sample, probably the one that you didn’t desire, as a gift embedded in the dotRunpeX.

Figure 15: Downloader that uses a reflection to load dotRunpeX delivering another Redline malware

Technical Analysis: Highlights

The old version of dotRunpeX:

  • Using custom obfuscation – only obfuscations of names
  • Configurable but limited (target for payload injection, elevation + UAC Bypass, XOR key for payload decryption)
  • Only one UAC Bypass technique
  • Using simple XOR to decrypt the main payload to be injected
  • Using D/Invoke similar technique to call native code (based on using GetDelegateForFunctionPointer()) – but using decoy syscall routine
  • Using D/Invoke for remapping of “ntdll.dll”

The new version of dotRunpeX:

  • Protected by a customized version of the KoiVM virtualizer
  • Highly configurable (disabling Anti-Malware services, Anti-VM, Anti-Sandbox, persistence settings, key for payload decryption, UAC bypass methods)
  • More UAC Bypass techniques
  • Using simple XOR to decrypt the main payload to be injected (omitted in the latest developed versions)
  • Abusing procexp driver (Sysinternals) to kill protected processes (Anti-Malware services)
  • Signs of being Russian based – procexp driver name Иисус.sys translated as “jesus.sys”

Similarities between both versions:

  • 64-bit executable files “.exe” written in .NET
  • Used to inject several different malware families
  • Using simple XOR to decrypt the main payload to be injected
  • Possible usage of the same UAC bypass technique (the new version of dotRunpeX has more techniques available)
Figure 16: UAC bypass technique
  • Using the same version information
Figure 17: DotRunpeX version information
  • Using the same .NET resource name BIDEN_HARRIS_PERFECT_ASSHOLE to hold the encrypted payload to be injected
Figure 18: Dotnet resource name of new version vs. old version
  • Using the same code injection technique – Process Hollowing
  • Using the same structured class for definitions of Native delegates
Figure 19: The same structured class for definitions of Native delegates

Full technical analysis – old version of dotRunpeX

For the analysis of the older version of dotRunpeX, sample SHA256: “65cac67ed2a084beff373d6aba6f914b8cba0caceda254a857def1df12f5154b” was used. This sample is a 64-bit executable file “.exe” written in .NET, implementing custom obfuscation – only obfuscations of names. The version information is consistent across all samples we analyzed, and we can notice the ProductName – RunpeX.Stub.Framework that could be some kind of first hint that we are dealing with a dotnet injector.

Figure 20: Consistent version information of the old dotRunpeX version

For simplicity, we partly deobfuscated the names of methods, their arguments, and local variables. Right in the Main() method, we can see simple XOR decryption of the resource BIDEN_HARRIS_PERFECT_ASSHOLE that contains an encrypted payload to be injected. The resource name was consistent across all samples we analyzed.

Figure 21: The main method leads to simple XOR decryption of the embedded payload

We can also see the namespace UACBypass with the class name UAC. This class implements UAC (User Account Control) bypass method, but it is not configured to use in this sample.

Figure 22: UAC bypass method

Method Inject() is implementing a code injection technique called “Process Hollowing”. We can notice spawning a process in a suspended state right in the picture below.

Figure 23: Creation of suspended process as a part of the Process Hollowing technique

This technique is nothing new in the world of malware development. Still, there is something interesting we can immediately spot once we check P/Invoke (technology that allows access to structs, callbacks, and functions in unmanaged libraries from managed code) defined methods of this sample. These methods can be seen in the ImplMap table, which is a part of .NET metadata.

Figure 24: The ImplMap table – the old version of the dotRunpeX

Certain WIN APIs or NT APIs must be used to perform the Process Hollowing technique. And as we saw in the ImplMap table, some of the most crucial APIs are missing. To be more specific, we cannot see any APIs related to unmapping and writing to remote process memory. The reason behind this is the usage of the D/Invoke framework to call certain NT API routines that could usually trigger attention.

D/Invoke contains powerful primitives that may be combined intelligently to dynamically invoke unmanaged code from disk or memory with careful precision. It relies on the usage of the dotnet method GetDelegateForFunctionPointer() and corresponding delegates definitions.

In this case, NT APIs ZwOpenSection, ZwMapViewOfSection, ZwUnmapViewOfSection, NtClose, NtWriteVirtualMemory, NtResumeThread, and RtlMoveMemory are implemented via D/Invoke. The corresponding definitions of delegates can be seen below.

Figure 25: The class for definitions of Native delegates

What is even more interesting, 4 NT APIs (ZwUnmapViewOfSection, NtWriteVirtualMemory, NtResumeThread, RtlMoveMemory) implemented via D/Invoke are using something that could be considered as an added PoC technique and is not a part of the original D/Invoke framework – syscall patching. For example, we can check how NtWriteVirtualMemory invocations are implemented via a method called CallNtWriteVirtualMemory().

Figure 26: Example of D/Invoke implementation that leads to syscall patching

First, what we can see is an altered usage of the D/Invoke framework in the method MapDllandGetProcAddress(). Each time this method is invoked, it will remap the specified library and obtain the desired function’s address. Before returning the address of the desired function, pointer arithmetic is used to move the pointer by 4 bytes so it points to the address of the syscall number. In this case, the “ntdll.dll” module gets remapped, returning the address of the NT API routine NtWriteVirtualMemory altered by 4 bytes offset.

Figure 27: Altered usage of the D/Invoke that returns the address pointing to the syscall number
Figure 28: NtWriteVirtualMemory address altered by 4 bytes offset points to its syscall number

The remapping of the module is used as an AV-evasion and Anti-Debug technique, as it results in unhooking and removing all set software breakpoints. The obtaining address of a certain native function is implemented via typical D/Invoke implementation – DynGetProcAddress(), which is responsible for in-memory parsing of the PE structure to find the address of the specified routine.

Figure 29: Typical in-memory parsing of the PE structure implemented via D/Invoke

Now back to the exciting part. As we can see in this case, DynGetProcAddress() is also used to find the address of NT API NtAddBootEntry, and we can call it a decoy routine. The decoy routine address will be used for syscall patching.

Figure 30: Decoy routine NtAddBootEntry used for syscall patching
  • Getting the address of the NtWriteVirtualMemory routine altered by 4 bytes offset (address of syscall number)
  • Getting the address of the decoy routine NtAddBootEntry
  • Copying 2 bytes from the altered address of NtWriteVirtualMemory (even though the syscall number is DWORD, these 2 bytes are enough and represent the syscall number of NtWriteVirtualMemory) to byte field SyscallStub (this field contains syscall stub code)
  • Patching address of NtAddBootEntry with byte field SyscallStub

Disassembling the default value of the SyscallStub makes it even more apparent why exactly 2 bytes are getting replaced with bytes from the altered address of the NtWriteVirtualMemory routine. These 2 bytes represent the syscall number of certain real function to be called.

Figure 31: Disassembling the default value of the byte field SyscallStub

Simply said, once the NtWriteVirtualMemory function is called, the only thing we will see from user mode will be an invocation of NtAddBootEntry.

We can use WinDbg “kernel mode debugging” to verify the mentioned execution flow. We can see that NT API NtAddBootEntry with the original syscall number 0x6a (on our target system) is used as a patched decoy routine. In the case where NtWriteVirtualMemory needs to be called, the syscall number of the decoy routine is patched with syscall number 0x3a (NtWriteVirtualMemory syscall number on our target system) and gets called.

Figure 32: WinDbg “kernel mode debugging” shows the execution flow caused by syscall patching

Full technical analysis – new version of dotRunpeX

For the analysis of the new version of dotRunpeX, sample SHA256: “44a11146173db0663a23787bffbb120f3955bc33e60e73ecc798953e9b34b2f2” was used. This sample is a 64-bit executable file “.exe” written in .NET, protected by KoiVM. The version information is the same as in the case of an older version of dotRunpeX and is consistent across all samples we analyzed. We can notice the ProductName – RunpeX.Stub.Framework again.

Figure 33: Consistent version information of the new dotRunpeX version

Right after opening the sample in dnSpyEx and leading to the entrypoint function – _sb() method, we can immediately confirm that this new version of dotRunpeX is protected by the KoiVM virtualizer. Despite the fact that most of the IL code is virtualized, we can still spot invocation of P/Invoke defined method CreateProcess that is used in a way to create a process in a suspended state – typically used for code injection technique “Process Hollowing”.

Figure 34: Creation of suspended process as a part of the Process Hollowing technique

After investigating more what was left lying around in .NET metadata, specifically in the ImplMap table, to find out what other methods are defined as P/Invoke and very likely used by this sample, we are getting surprisingly even more exciting findings than in the case of the older version of dotRunpeX. Apparently, the sample will perform not just code injection but also loading and communicating with the driver.

Figure 35: The ImplMap table – the new version of the dotRunpeX

The next that we immediately noticed is the usage of the same resource name as in the case of the older version – BIDEN_HARRIS_PERFECT_ASSHOLE – that contains an encrypted payload to be injected. The resource name was consistent across all samples we analyzed. Obviously, the decryption routine is hidden behind the code virtualization, but an educative guess will lead us to a simple XOR decryption routine using a password expressing the secret desires of the author – I_LOVE_HENTAIU2.

Figure 36: Simple XOR decryption of the .NET resource using password “I_LOVE_HENTAIU2”

Unfortunately, as dotRunpeX is still in high development and adding new features, the latest samples utilizing this injector changed the decryption scheme (no more simple XOR) to omit static extraction of embedded payloads.

As we pointed out before, the IL code is protected by the KoiVM virtualizer, so to continue with our analysis, we needed to come up with some approach to deal with the protected code and get something meaningful from that in a reasonable time. First, what came to our mind was to use a publicly available open-source KoiVM de-virtualizer called OldRod. This tool is fully workable for the vanilla version of KoiVM. It is even developed in a way that defeats some simple modifications of the original version of KoiVM (such as signature modifications of the methods in VMEntry class or changes in the default #Koi stream name).

Unfortunately for us, we are dealing with a customized version of KoiVM that modified the protector in a way that is not so simple to defeat. The original implementation of KoiVM defines 119 constant variables that are used to virtualize the code. These constants are used to define registers, flags, opcodes, etc. Assigned values of these constants are used for the proper execution of the virtualized code and are also needed for the de-virtualization process.

Figure 37: The original implementation of KoiVM defines 119 constants

When using the vanilla version of KoiVM, the resulting constants appear in the compiled, protected sample inside the Constants class as fields in the exact same order with ascending values of tokens. The order of constants and their corresponding tokens inside the compiled binary is something OldRod depends on.

Figure 38: The OldRod source code – automatic detection of constants

Although the OldRod tool is an absolute masterpiece and can deal with a custom order of constants when providing a custom constants mapping via configuration file (--config option), finding out the correct mapping of those constants could not be as simple as it sounds. Sometimes when a constant’s order is handmade change, it could be not so hard to map them correctly by analyzing their usage in code. Unfortunately, in the case of dotRunpeX, we can immediately see that values of those constants are affected by runtime arithmetic assignments (no problem to defeat this programmatically), but even worse is that they are scrambled in a very effective way that makes the correct mapping hard enough to consider this approach as not usable for getting some results in a reasonable time.

Figure 39: Runtime arithmetic assignments of scrambled constants

Even though we pointed out several facts about the extreme hardness of devirtualization, with precise code analysis and some hard moments during the constants mapping via their appropriate handlers, we were able to fully devirtualize the code. Despite the fully devirtualized code, we were still left with a non-fully runnable .NET Assembly that was still obfuscated with ConfuserEx obfuscator. To continue our madness, we were able to get rid of this obfuscation too.

To give a little spoiler about the functionality of the dotRunpeX injector and its use of procexp driver, fully devirtualized and deobfuscated code related to driver routines can be seen below.

Driver loading/unloading:

Figure 40: Devirtualized and deobfuscated code responsible for loading/unloading the driver

Communication with procexp device:

Figure 41: Devirtualized and deobfuscated code responsible for communication with procexp device

The process of devirtualization and deobfuscation is a subject to consider for its own blog post and won’t be covered further.

Normally, when it is impossible to devirtualize the code in a reasonable time, we are still left with few other options. The first of the options, quite a common approach when dealing with virtualized code, is to go with dynamic analysis using a debugger, DBI (Dynamic Binary Instrumentation), hooking, and WIN API tracing. As we are dealing with dotnet code, another approach to come out with could be some PoC using some knowledge from the .NET internals world. As researchers who love to bring something new to the community, we decided to combine both of these approaches, which resulted in developing new tools that were approved to be very effective.

To get more information about the code functionality, we started with the dynamic analysis approach using x64dbg. As we pointed out before, the ImplMap table containing P/Invoke-defined methods seems to be a good starting point for setting breakpoints in the debugger. Automating the process of parsing out the P/Invoke defined methods and converting it to x64dbg script leads us to the first tool we developed, called “ImplMap2x64dbg”.

ImplMap2x64dbg

Python script that uses dnfile module to properly parse .NET executable files and their metadata. This tool creates an x64dbg script for setting breakpoints on defined ImplMap (P/Invoke) methods of the .NET executable. This script can be downloaded in the last section of the article.

import dnfile, sys, os

def Main():
    if(len(sys.argv) != 2 or sys.argv[1] == '-h' or sys.argv[1] == '--help'):
        print("Description: Creates x64dbg script for setting breakpoints on defined ImplMap (PInvoke) methods of .NET executable")
        print(f"Usage: {os.path.basename(sys.argv[0])} <filepath>\n")
        sys.exit()

    file_path = sys.argv[1]
    script_path = file_path + "_x64dbg.txt"
    dn_file = dnfile.dnPE(file_path)

    if(dn_file.net is None or dn_file.net.metadata is None):
        print(f"{sys.argv[1]} is NOT a .NET executable !!!\n")
        sys.exit()
    if(dn_file.net.mdtables.ImplMap is None):
        print(f".NET executable '{sys.argv[1]}' has NO ImplMap !!!\n")
        sys.exit()

    # Getting all ImplMap methods and module scope
    implmap_table = dn_file.net.mdtables.ImplMap.rows
    implmap_modules = []
    implmap_methods = []
    [implmap_modules.append(row.ImportScope.row.Name.lower().replace(".dll", "")) for row in implmap_table if (row.ImportScope.row.Name.lower().replace(".dll", "") not in implmap_modules)]
    [implmap_methods.append(row.ImportName) for row in implmap_table if (row.ImportName not in implmap_methods)]

    # Creation of x64dbg script
    x64dbg_script = "; Replace charset depending APIs - ex. CreateProcess -> CreateProcessA or CreateProcessW !!!\n"
    for module in implmap_modules:
        x64dbg_script += f"loadlib {module}\n"
    for method in implmap_methods:
        x64dbg_script += f"SetBPX {method}\n"
    with open(script_path, "wt",encoding="utf-8") as f_scr:f_scr.write(x64dbg_script)
    print(f"x64dbg script created: '{script_path}'")

if __name__ == '__main__':
    Main()

Processing our dotRunpeX sample with “ImplMap2x64dbg” will result in the x64dbg script:

; Replace charset depending APIs - ex. CreateProcess -> CreateProcessA or CreateProcessW !!!
loadlib kernel32
loadlib ntdll
loadlib user32
loadlib advapi32
SetBPX VirtualAllocEx
SetBPX CreateProcessA
SetBPX CreateProcessW
SetBPX CreateRemoteThread
SetBPX Wow64SetThreadContext
SetBPX Wow64GetThreadContext
SetBPX NtResumeThread
SetBPX ZwUnmapViewOfSection
SetBPX NtWriteVirtualMemory
SetBPX MessageBoxA
SetBPX MessageBoxW
SetBPX GetModuleHandleA
SetBPX GetModuleHandleW
SetBPX FindWindowA
SetBPX FindWindowW
SetBPX GetProcAddress
SetBPX GetFileAttributesA
SetBPX GetFileAttributesW
SetBPX ShowWindow
SetBPX SetForegroundWindow
SetBPX Wow64DisableWow64FsRedirection
SetBPX Wow64RevertWow64FsRedirection
SetBPX CreateFileA
SetBPX CreateFileW
SetBPX RtlInitUnicodeString
SetBPX NtLoadDriver
SetBPX NtUnloadDriver
SetBPX OpenProcessToken
SetBPX LookupPrivilegeValueA
SetBPX LookupPrivilegeValueW
SetBPX AdjustTokenPrivileges
SetBPX CloseHandle
SetBPX NtQuerySystemInformation
SetBPX DeviceIoControl
SetBPX GetProcessHeap
SetBPX HeapFree
SetBPX HeapAlloc
SetBPX RtlCopyMemory

We focused mainly on certain WIN/NT APIs such as CreateProcessW, NtWriteVirtualMemory,CreateFileA, CreateFileW, NtLoadDriver, NtQuerySystemInformation, and DeviceIoControl as they are the interesting ones related to driver and process injection routines.

The first interesting WIN API call we can see is CreateFileW which is used to create a file in path C:\Users\XXX\AppData\Local\Temp\Иисус.sys.

Figure 42: CreateFileW used to create a file “Иисус.sys”

If we check the created file Иисус.sys (from the Russian language translated as “jesus.sys”), we will immediately find out it is a valid Process Explorer driver, version 16.43.

Figure 43: Created file “Иисус.sys” is a valid Process Explorer driver, version 16.43

We can see routine NtLoadDriver responsible for loading this driver where the argument points to DriverServiceName – \Registry\Machine\System\CurrentControlSet\Services\TaskKill that specifies a path to the driver’s registry key.

Figure 44: NtLoadDriver used to load procexp driver via its associated registry key
Figure 45: Content of the driver’s registry key “\Registry\Machine\System\CurrentControlSet\Services\TaskKill”

Connecting to the process explorer device follows.

Figure 46: Obtaining the handle of the process explorer device

One of the dotRunpeX AV-evasion techniques is killing a hardcoded list of Anti-Malware services with the help of a process explorer driver (procexp.sys). The reason behind the usage of process explorer driver is that the Anti-Malware service usually runs as a protected process, more specifically as PPL, to avoid disabling protection on the system caused by malicious activity. It is possible to abuse vulnerable versions of the procexp driver to close object handles of the protected process. Once enough handles are closed, the specific protected process will be killed. All samples we analyzed were abusing version 16.43 of this driver which is also the latest version vulnerable to this technique.

To obtain information about object handles, dotRunpeX uses NT API NtQuerySystemInformation with specified SystemInformationClass 0x10 that points to the undocumented structure [SYSTEM_HANDLE_INFORMATION]. This way, it finds all handles that belong to the protected process.

Figure 47: NtQuerySystemInformation used to obtain undocumented structure SYSTEM_HANDLE_INFORMATION

To process object handles of protected process, dotRunpeX uses WIN API DeviceIoControl to send IOCTL directly to the vulnerable procexp driver. The IOCTL “2201288708” (IOCTL_CLOSE_HANDLE) is in RDX register, and procexp driver routine processing this request is responsible for closing certain object handle of the specified process, regardless of whether the specified process is protected or not. Once enough object handles are closed, the Anti-Malware service is killed.

Figure 48: DeviceIoControl used to send the IOCTL “2201288708” to close the object handle of the protected process

We could also see that register R8 (lpInBuffer) points to data required to close the object handle. This data structure could be defined as follows:

typedef struct _ioControl
{
    ULONGLONG ulPID;
    PVOID lpObjectAddress;
    ULONGLONG ulSize;
    ULONGLONG ulHandle;
} PROCEXP_DATA_EXCHANGE, *PPROCEXP_DATA_EXCHANGE;

Let’s compare the procexp driver version used by all samples of dotRunpeX (version 16.43 – compiled 2021-08-17) and the latest version of the procexp driver (version 17.02 – compiled 2022-11-10). We can immediately spot the added patching code that is responsible for disabling the possibility of closing object handles of protected processes.

Figure 49: Process Explorer driver version 16.43 vs. 17.02

This technique of closing object handles of protected processes using the process explorer driver is well documented and part of an open-source project called Backstab. Process explorer drivers version 17.0+ are already patched.

After killing specific protected processes, Process Hollowing is what follows using WIN API CreateProcessW to start the process as suspended (in this case C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe) and direct NT API NtWriteVirtualMemory to write embedded payload of dotRunpeX into the newly created remote process.

It turned out that with an approach of dynamic analysis that focused on the native layer and certain usage of WIN/NT APIs, we got some interesting findings of this virtualized dotnet injector that could be used for automation and mass processing:

  • Each dotRunpeX sample has an embedded payload of a certain malware family to be injected
  • Each dotRunpeX sample has an embedded procexp driver to kill protected processes
  • There is very likely some kind of config hidden behind the virtualized code that specifies the target process for Process Hollowing, a protected process list to be killed (Anti-Malware services), and probably other interesting configurable things.

Encouraged by these findings, we can move forward to some automation using knowledge from the .NET internals world. When we are talking about dotnet, we can immediately think of code being managed by .NET runtime. More things are being managed, and among them is one very important for our further process, and that is so-called “Memory Management”. The types of memory in dotnet are stack and .NET heap. In the dotnet world, we do not need to bother with memory allocation/deallocation because these routines are handled by .NET runtime and garbage collector. Memory management of dotnet somehow needs to know what to allocate, where, and how; the same goes for deallocation/freeing of memory. Allocation on the .NET heap occurs once we talk about reference types inheriting from System.Object (class, object, string…). These objects are saved on the .NET heap, and for the purpose of their automatic management, they are accompanied by certain metadata information such as their type, references, and size. Even better, the automatic memory deallocation of no longer referenced objects does not occur immediately – the garbage collector takes care of this in some time intervals, which could be several minutes. Particular objects like “static objects” survive garbage collections and live till the application ends.

This means that if we could enumerate objects on the .NET heap, we could also get information related to their types and size that can serve for their appropriate reconstruction. Creating this kind of tool would be very likely time-consuming, but luckily for us, there is already created dotnet process and crash dump introspection open-source library ClrMD Microsoft.Diagnostics.Runtime developed by Microsoft that could be used precisely for object reconstruction from .NET heap. Why is that so important?

In a certain moment of dotRunpeX execution, embedded payload, procexp driver, and some kind of config must appear in a decrypted state. Their content will likely be assigned to some object allocated on the .NET heap. For these, we could expect byte array byte[] or string. That also means that if we could control the execution of dotRunpeX and suspend it in a state we assume to be the right moment for those object reconstructions, we would be able to get all that we need in a decrypted state.

One of the right moments for suspending and introspecting the dotRunpeX process could be an invocation of WIN API CreateProcessW used for Process Hollowing. This was approved to be the correct assumption and led us to develop the hooking library “CProcessW_Hook” exactly for this purpose.

CProcessW_Hook

Native hooking library using minhook framework (The Minimalistic x86/x64 API Hooking Library for Windows). The code provided below serves the purpose of hooking the WIN API function CreateProcessW, which is used in the dotRunpeX injector for process creation that is later used as a target for code injection (PE Hollowing). Once the CreateProcessW function is hooked and called in the target process, the whole process gets suspended to introspect. Certain process creations are filtered (powershell, conhost) as they can be spawned for other functionalities of dotRunpeX according to config (example modification of Windows Defender settings). We need to suspend the process only in a state before performing code injection (where all required objects are already decrypted on the .NET heap).

#include <windows.h>
#include <string.h>
#include "pch.h"
#include "MinHook.h"

#pragma warning(disable : 4996)

#if defined _M_X64
#pragma comment(lib, "libMinHook.x64.lib")
#elif defined _M_IX86
#pragma comment(lib, "libMinHook.x86.lib")
#endif

typedef LONG (__stdcall* NTSUSPENDPROCESS)(HANDLE ProcessHandle);
typedef BOOL (__stdcall* CREATEPROCESSW)(LPCWSTR, LPCWSTR, LPSECURITY_ATTRIBUTES, LPSECURITY_ATTRIBUTES, BOOL, DWORD, LPVOID, LPCWSTR, LPSTARTUPINFOW, LPPROCESS_INFORMATION);

CREATEPROCESSW fpCreateProcessW = NULL;

__declspec(dllexport) void __cdecl Decoy() 
{
    Sleep(1000);
}

int __stdcall DetourCreateProcessW(LPCWSTR lpApplicationName, LPWSTR lpCommandLine, LPSECURITY_ATTRIBUTES lpProcessAttributes, LPSECURITY_ATTRIBUTES lpThreadAttributes, BOOL bInheritHandles, DWORD dwCreationFlags, LPVOID lpEnvironment, LPCWSTR lpCurrentDirectory, LPSTARTUPINFOW lpStartupInfo, LPPROCESS_INFORMATION lpProcessInformation)
{
    LPCWSTR ignoredProcess[2] = { L"powershell", L"conhost" };
    for (int i = 0; i < 2; i++)
    {
        if (wcsstr(_wcslwr(lpApplicationName), ignoredProcess[i]))
        {
            return fpCreateProcessW(lpApplicationName, lpCommandLine, lpProcessAttributes, lpThreadAttributes, bInheritHandles, dwCreationFlags, lpEnvironment, lpCurrentDirectory, lpStartupInfo, lpProcessInformation);
        }
    }

    HMODULE hNtdll = GetModuleHandleA("ntdll.dll");
    if (!hNtdll)
    {
        ExitProcess(0);
    }
    NTSUSPENDPROCESS NtSuspendProcess = (NTSUSPENDPROCESS)GetProcAddress(hNtdll, "NtSuspendProcess");
    if (!NtSuspendProcess)
    {
        CloseHandle(hNtdll);
        ExitProcess(0);
    }
    HMODULE cProcess = GetCurrentProcess();
    if (!cProcess) 
    {
        CloseHandle(hNtdll);
        ExitProcess(0); 
    }
    NtSuspendProcess(cProcess);
    ExitProcess(0);
    return  1;
}

BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
        case DLL_PROCESS_ATTACH:
            if (MH_Initialize() != MH_OK)
            {
                return 1;
            }
            if (MH_CreateHook(&CreateProcessW, &DetourCreateProcessW, (LPVOID*)(&fpCreateProcessW)) != MH_OK)
            {
                return 1;
            }
            if (MH_EnableHook(&CreateProcessW) != MH_OK)
            {
                return 1;
            }
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
        case DLL_PROCESS_DETACH:
            break;
    }
    return TRUE;
}

We could see that all hooking logic is executed right upon loading this library inside the function DllMain(). Another important thing to note is that we defined the export function Decoy(), which won’t be ever executed or called but is needed later on for our preinjection technique.

With the hooking library “CProcessW_Hook.dll” in its place, we can move on to create an injector and extractor. This points to the main tool provided below – dotRunpeX extractor “Invoke-DotRunpeXextract”.

Invoke-DotRunpeXextract

PowerShell module that enables the extraction of payload, procexp driver, and config from dotRunpeX. The tool is written in PowerShell scripting language using preinjection of native hooking library “CProcessW_Hook.dll” (using AsmResolver) and .NET objects reconstruction from .NET heap (using ClrMD). It uses a dynamic approach for extraction, so samples are executed in a managed way (use only in VM). Using PowerShell 7.3+, clrMD v2.2.343001 (net6.0), AsmResolver v5.0.0 (net6.0).

We provide two versions of this tool that can be downloaded along with the hooking library in the last section of this article. One is created multi-threaded as a PowerShell module for the best performance and usage. The second version of this tool is a single-threaded script with the same functionality that could be used for simple debugging and troubleshooting and can more easily serve to create several snippets with similar functionality.

The whole code of this PowerShell module is annotated and commented on in a way to be easy to understand its core features. We will briefly describe the core functionality of this tool, like the preinjection technique of the hooking library using AsmResolver and implemented logic behind the extraction.

At first, this tool modifies the PE structure of dotRunpeX using AsmResolver. AsmResolver is well known for its capability to inspect dotnet executables and their related metadata, but it also allows access to low-level structures of PE to modify them. These PE structure modifications are used to implement our so-called PoC technique for the purpose of dll preinjection to a 64-bit dotnet executable. We are talking about adding a new import entry for the native hooking library into the .NET Assembly. Since dotRunpeX is a 64-bit executable, and it turned out that, unlike the 32-bit dotnet executables, the 64-bit ones don’t even have an import directory, we started building one from scratch right inside the function PatchBinaryWithDllInjection(). In this function, we can see that we are creating new data sections, .idata and .data, where our newly built IDT (Import Directory Table) and IAT (Import Address Table) will be placed. To get our hooking library “CProcessW_Hook.dll” preinjected right upon process start and let the windows loader do for us the hard work, we are creating an import entry with exported function Decoy() that was defined in the hooking library. As we are dealing with dotnet and adding native import, IL Only flag inside the .NET Directory is not true anymore and needs to be patched.

function PatchBinaryWithDllInjection($pathToSample, $patchedSample, $dllHookingName) 
{
    # Exported function name "Decoy" from hooking library will be used for Import Directory creation 
    $symbolNameToImport = [AsmResolver.PE.PEImage]::FromFile($dllHookingName).Exports.Entries[0].Name # Decoy
    # We need to work with pefile layer to expose sections - creation of Import Directory and IAT
    $pefile = [AsmResolver.PE.File.PEFile]::FromFile($pathToSample)

    # Creation of Import Directory from scratch
    $impDirBuff = [AsmResolver.PE.Imports.Builder.ImportDirectoryBuffer]::new($false)
    $impModule = [AsmResolver.PE.Imports.ImportedModule]::new($dllHookingName)
    $symbol = [AsmResolver.PE.Imports.ImportedSymbol]::new(0,$symbolNameToImport)
    $impModule.Symbols.Add($symbol)
    $impDirBuff.AddModule($impModule)

    # Creation of ".idata" section where Import Directory will be placed
    $idataSection = [AsmResolver.PE.File.PESection]::new(".idata", [AsmResolver.PE.File.Headers.SectionFlags]::MemoryRead -bor [AsmResolver.PE.File.Headers.SectionFlags]::ContentInitializedData)
    $idataSection.Contents = $impDirBuff
    $pefile.Sections.Add($idataSection)

    # Creation of ".data" section where IAT will be placed
    $dataSection = [AsmResolver.PE.File.PESection]::new(".data", [AsmResolver.PE.File.Headers.SectionFlags]::MemoryRead -bor [AsmResolver.PE.File.Headers.SectionFlags]::MemoryWrite -bor [AsmResolver.PE.File.Headers.SectionFlags]::ContentInitializedData)
    $dataSection.Contents = $impDirBuff.ImportAddressDirectory
    $pefile.Sections.Add($dataSection)

    # Remove ASLR (no reloc)
    $pefile.OptionalHeader.DllCharacteristics = $pefile.OptionalHeader.DllCharacteristics -bxor [AsmResolver.PE.File.Headers.DllCharacteristics]::DynamicBase
    # Update offsets and RVA of newly created data sections (so we can work with them later on)
    $pefile.UpdateHeaders()

    # Update info about new data directories in context of pefile - Import Directory, IAT
    $pefile.OptionalHeader.DataDirectories[[AsmResolver.PE.File.Headers.DataDirectoryIndex]::ImportDirectory] = [AsmResolver.PE.File.Headers.DataDirectory]::new($idataSection.Rva, $idataSection.GetPhysicalSize())
    $pefile.OptionalHeader.DataDirectories[[AsmResolver.PE.File.Headers.DataDirectoryIndex]::IatDirectory] = [AsmResolver.PE.File.Headers.DataDirectory]::new($dataSection.Rva, $dataSection.GetPhysicalSize())
    $pefile.Write($patchedSample)

    # We need to do some custom patching of IL only flag inside .NET Directory (it is easier than making custom writer preserving all PE sections and meta) - we are adding native imports so IL only is not true anymore
    $dotnetDirectoryRVA = $pefile.OptionalHeader.DataDirectories[[AsmResolver.PE.File.Headers.DataDirectoryIndex]::ClrDirectory].VirtualAddress
    $dotnetDirectoryFileOffset = $pefile.RvaToFileOffset($dotnetDirectoryRVA)
    $dotnetDirectoryILFlagsFileOffset = $dotnetDirectoryFileOffset + 16
    $filestream = [System.IO.FileStream]::new($patchedSample, [System.IO.FileMode]::Open, [System.IO.FileAccess]::ReadWrite)
    $filestream.Position = $dotnetDirectoryILFlagsFileOffset
    $filestream.Write([byte[]]::new(4), 0, 4) # Wipe the IL only flags
    $filestream.Close()   
}

A comparison of the dotRunpeX sample before and after the described modification of the PE structure can be seen in the picture below.

Figure 50: PE structure of the dotRunpeX sample before and after modification used for dll preinjection

Now, we get to the state where our modified binary could be executed. With the hooking library in its place, the dotRunpeX process gets suspended right during the call to WIN API CreateProcessW. This exact routine is implemented in the function StartProcessWaitSuspended().

function StartProcessWaitSuspended($patchedSample)
{
    $process = [System.Diagnostics.Process]::Start($patchedSample)
    while ($process.Threads.Where{$_.ThreadState -ne [System.Diagnostics.ThreadState]::Wait -and $_.WaitReason -ne [System.Diagnostics.ThreadWaitReason]::Suspended}) 
    {
        Start-Sleep -Milliseconds 500
        $process.Refresh()
    }
    return $process  
}

Once the process is suspended, it is ready to be introspected. The whole logic behind the introspection of the dotRunpeX process can be seen in the function GetPayloadAndConfig(). In this function, we use the clrMD library to attach to the desired process and enumerate all System.Byte[] objects that are currently allocated on the .NET heap. To reconstruct the payload intended to be injected, we have implemented some dummy logic to find byte array objects larger than 1KB and starting with the “MZ” header. Despite the fact how it sounds, it has proven to be enough to fulfill our needs.

The logic behind finding the object corresponding to the process explorer driver and config is slightly different. First of all, the procexp driver and constants related to the config are saved in the same object. We assume that this is a result of the combination of usage KoiVM virtualizer and ConfuserEx obfuscator together as ConfuserEx usually puts defined constants to one blob of byte array and resolves them during the runtime once they are needed. After the logic finds this kind of byte blob, it separates the process explorer driver and config and pushes the config for further processing.

function GetPayloadAndConfig($process) 
{   # DataTarget is our suspended process
    $dataTarget = [Microsoft.Diagnostics.Runtime.DataTarget]::AttachToProcess($process.Id, $false)  
    Start-Sleep -Seconds 1 # Better to wait for ClrMD - to properly initialize DataTarget 
    $clrInfo = $dataTarget.ClrVersions[0]
    $clrRuntime = $clrInfo.CreateRuntime()
    
    # Getting all byte array objects from .NET Heap and sort them by size descending
    $objects = $clrRuntime.Heap.EnumerateObjects().ToArray().Where{$_.Type.Name -eq "System.Byte[]"} | Sort-Object -Property Size -Descending
    # Find payload to be injected - should be the largest byte array containing PE
    $payload = @()
    foreach ($object in $objects)
    {   
        # Check if byte array possible valid PE
        if($object.AsArray().Length -gt 1024)
        {
            if((Compare-Object ($object.AsArray().ReadValues[byte](0,2)) ([byte[]] 0x4d,0x5a)).Length -eq 0)
            {
                $payload = $object.AsArray().ReadValues[byte](0, $object.AsArray().Length)
                break
            }
        }
    }
    if(-not $payload){Write-Host "Payload to be injected NOT found in sample:"$process.MainModule.ModuleName"!!!" -ForegroundColor Red}
    
    # Find procexp driver + config (first 8 bytes of byte array skipped -> should be related to procexp PE size)
    $procexpAndConfig = @()
    foreach ($object in $objects)
    {   
        # Check if byte array possible procexp PE and config
        if($object.AsArray().Length -gt 1024)
        {
            if((Compare-Object ($object.AsArray().ReadValues[byte](8,2)) ([byte[]] 0x4d,0x5a)).Length -eq 0)
            {
                $procexpAndConfig = $object.AsArray().ReadValues[byte](0, $object.AsArray().Length)
                break
            }
        }
    }
    if(-not $procexpAndConfig)
    {
        Write-Host "Procexp driver + config NOT found in sample:"$process.MainModule.ModuleName"!!!" -ForegroundColor Red
        $procexp = $null
        $config = $null
        return $payload, $procexp, $config
    }   
    # Process procexp and config
    $procexpSize = [bitconverter]::ToInt32($procexpAndConfig[4..7], 0)
    $procexp = $procexpAndConfig[8..($procexpSize+7)]
    $config = $procexpAndConfig[($procexpSize +8)..$procexpAndConfig.Length]
    
    return $payload, $procexp, $config
}

The so-called config is actually a bunch of constants where some of them serve as a configuration of dotRunpeX. This config needs to be parsed in the function ParseConfig() as it appears to be in some kind of structure where every string is preceded with its length and if needed, padded to have length divisible by 4, as shown in the picture below.

Figure 51: Unparsed config structure
function ParseConfig($config)
{
    $memStream = [System.IO.MemoryStream]::new($config, $true)
    $strLength = [byte[]]::new(4)
    $parsedConfig = ""

    while ($memStream.Position -lt $memStream.Length) 
    {
        $memStream.Read($strLength, 0, 4) | Out-Null
        $length = [bitconverter]::ToInt32($strLength, 0)
        $buffer = [byte[]]::new($length)
        $memStream.Read($buffer , 0, $length) | Out-Null
        $parsedConfig += [System.Text.Encoding]::UTF8.GetString($buffer) + "`n"
        if(($memStream.Position % 4) -ne 0)
        {
            $memStream.Position += 4 - ($memStream.Position % 4)
        }
    }
    $memStream.Close()
    return $parsedConfig
}

Once we have properly parsed the config, it is saved with extracted payload and process explorer driver, the suspended process gets killed, and the modified dotRunpeX sample is removed.

Example execution of “Invoke-DotRunpeXextract” and mass processing of samples could be seen below (2min GIF):

Figure 52: Execution of “Invoke-DotRunpeXextract” (2min GIF)

As pointed out before, “Invoke-DotRunpeXextract” will produce a payload to be injected, procexp driver, and parsed constants values where some of them could be referred to as config. Example config file content for our analyzed sample of the dotRunpeX:

False
True
SOFTWARE\Microsoft\Windows\CurrentVersion\Run
C14615024653444192E5F79157E215D3
"
I_LOVE_HENTAIU2
C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe
Error
2345RTProtect
2345SafeCenterSvc
2345SafeSvc
2345SafeTray
kxetray
kxescore
kxemain
kwsprotect64
kscan
HipsTray
HipsDaemon
360sd
360rp
QQPCTray
QQPCRTP
360tray
360leakfixer
360Safe
ZhuDongFangYu
MultiTip
AvastSvc
sched
avp
McSvHost
avconfig
bdagent
MsMpEng
wireshark
MpCmdRun
ndd32
nod32
nod32krn
eguiProxy
ekrn
Software\Classes\ms-settings\shell\open\command
DelegateExecute
cmd.exe
/C computerdefaults.exe
Run without emulation
Select * from Win32_ComputerSystem
Manufacturer
microsoft corporation
Model
VIRTUAL
vmware
VirtualBox
This file can't run into Virtual Machines.
root\CIMV2
SELECT * FROM Win32_VideoController
Name
VMware
VBox
Run using valid operating system
SbieDll.dll
USER
SANDBOX
VIRUS
MALWARE
SCHMIDTI
CURRENTUSER
\VIRUS
SAMPLE
C:ile.exe
Afx:400000:0
HARDWARE\DEVICEMAP\Scsi\Scsi Port 0\Scsi Bus 0\Target Id 0\Logical Unit Id 0
Identifier
VBOX
HARDWARE\Description\System
SystemBiosVersion
VideoBiosVersion
VIRTUALBOX
SOFTWARE\Oracle\VirtualBox Guest Additions
noValueButYesKey
C:\WINDOWS\system32\drivers\VBoxMouse.sys
VMWARE
SOFTWARE\VMware, Inc.\VMware Tools
HARDWARE\DEVICEMAP\Scsi\Scsi Port 1\Scsi Bus 0\Target Id 0\Logical Unit Id 0
HARDWARE\DEVICEMAP\Scsi\Scsi Port 2\Scsi Bus 0\Target Id 0\Logical Unit Id 0
SYSTEM\ControlSet001\Services\Disk\Enum
0
SYSTEM\ControlSet001\Control\Class\{4D36E968-E325-11CE-BFC1-08002BE10318}\0000
DriverDesc
SYSTEM\ControlSet001\Control\Class\{4D36E968-E325-11CE-BFC1-08002BE10318}\0000\Settings
Device Description
InstallPath
C:\PROGRAM FILES\VMWARE\VMWARE TOOLS\
C:\WINDOWS\system32\drivers\vmmouse.sys
C:\WINDOWS\system32\drivers\vmhgfs.sys
kernel32.dll
wine_get_unix_file_name
QEMU
\\.\ROOT\cimv2
Description
VM Additions S3 Trio32/64
S3 Trio32/64
VirtualBox Graphics Adapter
VMware SVGA II
noKey
Fatal 'Error
C:\windows\system32\cmd.exe
/K "fodhelper.exe"
C:\windows\temp
\
.inf
REPLACE_COMMAND_LINE
/au 
cmstp
{ENTER}
[version]
Signature=$chicago$
AdvancedINF=2.5
[DefaultInstall]
CustomDestination=CustInstDestSectionAllUsers
RunPreSetupCommands=RunPreSetupCommandsSection
[RunPreSetupCommandsSection]
; Commands Here will be run Before Setup Begins to install
REPLACE_COMMAND_LINE
taskkill /IM cmstp.exe /F
[CustInstDestSectionAllUsers]
49000,49001=AllUSer_LDIDSection, 7
[AllUSer_LDIDSection]
"HKLM", "SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\CMMGR32.EXE", "ProfileInstallPath", "%UnexpectedError%", ""
[Strings]
ServiceName="CorpVPN"
ShortSvcName="CorpVPN"
c:\windows\system32\cmstp.exe
Windows 1
Windows 8
Windows 7
fodhelper
Software\Classes\exefile\shell\open\command
slui
Software\Classes\mscfile\shell\open\command
eventvwr
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
ProductName
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Notifications\Settings\Windows.SystemToast.SecurityAndMaintenance
Enabled
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
EnableLUA
powershell
Software\Classes\Folder\shell\open\command
SOFTWARE\Microsoft\Windows Defender\Exclusions\Paths
Add-MpPreference -ExclusionPath "
" -Force
Иисус.sys
\Registry\Machine\System\CurrentControlSet\Services\TaskKill
System\CurrentControlSet\Services\TaskKill
\??\
Type
ErrorControl
Start
ImagePath
\\.\
SeDebugPrivilege
SeLoadDriverPrivilege
\KnownDlls\
ntdll.dll
ZwOpenSection
ZwMapViewOfSection
NtClose
ZwUnmapViewOfSection
MZ
_4
BIDEN_HARRIS_PERFECT_ASSHOLE

We can easily spot configuration strings related to persistence settings, resource name and its decryption key (where .NET resource contains payload to be injected), target binary for the payload to be injected in, Anti-Malware service names to be killed, UAC bypass, Anti-VM, Anti-Sandbox, procexp driver installation path and its name, etc.

We provide two versions of this tool that can process just one sample or mass-process the directory of samples. For the best performance, the multi-threaded PowerShell module is recommended use. Still, for troubleshooting, simple modification, and easy debugging, we are also providing a single-threaded script with the same functionality as we expect soon some modification in dotRunpeX code where appropriate changes in the code of the tool or hooking library would be needed.

Conclusion

By monitoring this new threat for several months, we got deep insight into its evolution, delivery methods, and how it was abused to deliver a wide scale of different malware families.

Over time, we consider dotRunpeX to be in high development adding new features on regular bases and getting more popularity and attention every day. Because of the rising usage of this injector, we developed and provided several tools to automate the analysis of this virtualized dotnet code.

Some of the developed tools described in this report introduced PoC methods and can serve for developing other tools with similar functionality. We showed how open-source libraries such as AsmResolver and clrMD could be used in a real-world example to support the research and to help with the reverse engineering of protected code.

In this report, we provided an in-depth analysis of both versions of the dotRunpeX injector, the similarities between them, and described the main interesting techniques they use, such as abuse of the vulnerable process explorer driver, code virtualization caused by the usage of KoiVM protector, modification of D/Invoke framework with decoy syscall patching.

Our analysis and conclusions are based on dozens of campaigns we spotted in the wild and hundreds of samples that were mass processed.

Because of the high development of dotRunpeX, we believe that provided tools would need some modification soon as a reaction to changes in dotRunpeX. Still, with provided source codes, it should be relatively easy to work around these changes for other researchers.

Check Point customers remain protected from the threats described in this blog, including all its variants. Check Point’s Threat Emulation protects networks against unknown threats in web downloads and e-mail attachments. The Threat Emulation engine picks up malware at the initial phase before it enters the network. The engine quickly quarantines and runs the files in a virtual sandbox environment, which imitates a standard operating system, to discover malicious behavior at the exploit phase.

Harmony Email & Office deploys between the inbox and its native security. The solution secures inbound, outbound, and internal email from phishing attacks that evade platform-provided solutions and email gateways. It works with these other solutions and doesn’t require any MX record changes that broadcast security protocols to hackers.

IOCs

SHA256 HashVersionMalware family of embedded payload
1e7614f757d40a2f5e2f4bd5597d04878768a9c01aa5f9f23d6c87660f7f0fbcOLDLokibot
68ae2ee5ed7e793c1a49cbf1b0dd7f5a3de9cb783b51b0953880994a79037326OLDLokibot
317e6817bba0f54e1547dd9acf24ee17a4cda1b97328cc69dc1ec16e11c258fcOLDRedline
65cac67ed2a084beff373d6aba6f914b8cba0caceda254a857def1df12f5154bOLDSnakeKeylogger
81763d8e3b42d07d76b0a74eda4e759981971635d62072c8da91251fc849b91eOLDSnakeKeylogger
0e11704fcc3c36832ba98b80ea44a3013660d1ed3fb48158b982fed9f9050391NEWAgentTesla
0f9e27ec1ed021fd7375ca46f233c06b354d12d57aed44132208cd9308bfee11NEWAgentTesla
881a337aa85a4b01c08706ab941573c5dc9b76ea0e4e1c2693a9b4aa4453ec8cNEWAgentTesla
feae44d8927dd41feaed997b3dbf7b41933496d6285b79554b83e72ae8a045c4NEWAgentTesla
1c1fcc4133af77f07d0c0299d0320aa9f447748ebead74b429f73c44d950e38bNEWAgentTesla
35c11f7315d2e5d04d783de4314d8cde2def382f1e3fc49ccc555337c54d63ccNEWAgentTesla
4068637c121888476533a3bbb16bec6bc3b4f81f7b9de635ef3576d56dc54c75NEWAgentTesla
40df5a6e6dcadbe576ce4a8b01cfb82bf3f56a87bae674200e60814eab666c6dNEWAgentTesla
8a0d6e40e545d40956194230f03608859f2a47420a9b11b199142641bc6419eeNEWAgentTesla
7c3803c09a0370aa6484d8ad2f5690b96212d98e45fc8f9cb6022f87dff637fcNEWAgentTesla
93e2ea6f021951369028b73637d9558c8baf3c99d9de1a2a60c1461cb9d571bfNEWAgentTesla
d95298befdde567b31571d16f327840fa0f0dd9c54bf876531820910418a52b6NEWAgentTesla
149af913afd7eb2773386d14e88a46449cbc9096e0748cfbaa2e061b59525bf0NEWAgentTesla
a73f134ab62a5c23a8c8bafabbfbd5e0408c826ba5418488639724708ec5ef28NEWAgentTesla
aca4d6278f31f374262e0388d16ee6fdcdbbad8257374f1feaabf75b0ec23157NEWAgentTesla
50451fda27fd8569c7b32bfe82197b82a8637cac928164e1b091a389060e957eNEWAgentTesla
9ed8eeb1db8909c96a958d91213093d2488dc172a8d22ba62657b9bfeb044fecNEWAgentTesla
6c08c0654726c2f793b5191d5e7c74fdf3a2461118a45aa8527a0a30e3f256fdNEWAgentTesla
283cd48dc1368b6852c2f3168bf7a78ad593df010d9a67ed1c938508da5de783NEWAgentTesla
b019a0535ca7466d7884825542ac6910fe037913118e1136dcac7e9ef3dc0dc9NEWAgentTesla
b1c9b356c50230629c4697b0527fd7a0fa8d6f0e8342a1eb5b5a4f90d8f0eb86NEWAgentTesla
5bbd9513f0872d23ca43dd553a63a12882be274fef983fab427721257d60eaecNEWAgentTesla
9d9940b60809e3c10cd4540f8e589626a293244a999bea16c259f9712969a742NEWAgentTesla
cd4c821e329ec1f7bfe7ecd39a6020867348b722e8c84a05c7eb32f8d5a2f4dbNEWAgentTesla
cddf8b8da972cb2e560c70d01366f582445441864fcff884b8194eb6c21a768cNEWAgentTesla
6c367333c677c2268df9deaff6ad4e711e73e53504aa1aa845bebfbfe635f1d2NEWArrowRAT
5e3588e8ddebd61c2bd6dab4b87f601bd6a4857b33eb281cb5059c29cfe62b80NEWAsyncRat
244f2d4f3c34d00babef5f1765e91c0abda9dbd1d131fc93ecb48c91ecc801a8NEWAsyncRat
95793df9284fe35c0491e5cfa36bc8f49fd426ccdf35f5fe2f098e07d160a4dcNEWAveMaria/WarzoneRAT
55ee7efcb3d1d2e0eac0ecadd651d6a299de82d94347ef9862bc981ae619532bNEWBitRAT
13081992c0ef5c52c2b6224f3ff1ab38160bca9424e7c0470e0c175c920bdc9dNEWCryptocurrency Stealer
0daef2c2bf086312037ebc91beec0302a7e4d1750f260d02bf815bd13c611559NEWDownloader
331ad58c524100da7e459e5c3943e970414617f60b3ed0f1a74f3bf189aafea7NEWDownloader
44a11146173db0663a23787bffbb120f3955bc33e60e73ecc798953e9b34b2f2NEWDownloader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er
7120cf1ad3fdcae7ba6956749a8988e8181837a05948b432cec6ae11229b1d12NEWLgoogLoader
304847c69875ec59995fbb453f8d1106f80c5eb380ae6b8676e76f5372290194NEWNetWire
25fbe0ff3274b4bc981fa6ec0459e9b95cec6397194e10ea6287bf4b899a9b07NEWPrivateLoader
1bc7fc0a4796f7780223b4f0bf8d6816b3721f0b52eedc0df9a32dc4ea4829e8NEWPrivateLoader
75236a06aadafc69cc5aa8032468869fb868a9a100b687f19c66be03410c2487NEWPrivateLoader
ee0d55b9a2d03c5bea9f69f98b042ab7b3064366f335a8a53096387876bf48d7NEWPrivateLoader
8de23e90bac05911cbfb6b036c6808ce7c244e4e875cb7edcdb90f75e89e5476NEWPrivateLoader
10bbfa36ddd8ea6038e2071320ee84f7a9208a5be3a4dda448e83393cdf39a4dNEWPrivateLoader
ff72f619907a25f3d99f0c3aa84710c6ff6cb4c3fd8ebad14f85f96c6da49222NEWPrivateLoader
242e1c82269725c01108e52376be8ddad39ab29da49356d10e527af6d78058f5NEWPrivateLoader
ae4d2054a6e1f9ba2c269eace61aac7259adb0645d18da82779717d83174837dNEWPrivateLoader
bf7b127b1bb81b68439851386cd3d1600bb8b9ec56135e668a88062d913410ddNEWPrivateLoader
b8bb071899ae7bd16a328c0998b3cd40261d61e564ac77f9bf3e495fab0ad267NEWQuasarRAT
17af8118607b9fc1f7b6aa82fd72f4fc115320d293e103dfe356706bb7c581b7NEWRecordBreaker – Raccoon Stealer 2.0
366284c1a0577937c86744349ac47e6e578da500ada3deb857ff233d9851ee6bNEWRecordBreaker – Raccoon Stealer 2.0
3e50f0eaf02d12653d5f757372240adcb5c16a5ab647a667637ba4c50d37aaadNEWRecordBreaker – Raccoon Stealer 2.0
47849f610a30d72660b1725a0b18d78c5204257b3740641727bdcbfd1ebd466aNEWRecordBreaker – Raccoon Stealer 2.0
507f413ac42df115988df498a90fc1ae610cafb66cb30a3a7de53e71ec90e7cdNEWRecordBreaker – Raccoon Stealer 2.0
57f261cc442dd9a4f1cd4ffd281c9855f4f9a736abffaf539d9df2a6ea0dd409NEWRecordBreaker – Raccoon Stealer 2.0
76eed1849d0a0474f9e0a58afcda2cc1ea7af316535b4b4b27ff810a162d4f8fNEWRecordBreaker – Raccoon Stealer 2.0
855b2e04c323a269d3731c093f0bc80ab3497a69ab8d2967847451a87f04fb0aNEWRecordBreaker – Raccoon Stealer 2.0
87134629723b2c6f4d0a74c35fdce89653471d9880b23f4faea6664ae151db0eNEWRecordBreaker – Raccoon Stealer 2.0
8bcc23ec881d61839fc57e8ec7425ac5ed625425fbf265fcb53ad73a73825b18NEWRecordBreaker – Raccoon Stealer 2.0
9177ba0c649f08fa6367d04091a7672fedb82215b26e08346645544f0631ebfdNEWRecordBreaker – Raccoon Stealer 2.0
9246ed27032429f234888b2713529001344850c608cab9f5ab7274195d330becNEWRecordBreaker – Raccoon Stealer 2.0
a487e959e59bc9500c43ac270eaf345eaf28173b07ed7dd82b2495aa19cdab88NEWRecordBreaker – Raccoon Stealer 2.0
ada1679a193c9b17b206b3d9ff2a19d64c6c8c5f882a321381c9d5347a8b4b3eNEWRecordBreaker – Raccoon Stealer 2.0
c1be6f792bd51d23d848e54cd217bdf9edcbb2b89df741190929f6fa327a10cbNEWRecordBreaker – Raccoon Stealer 2.0
db8ed3e6dd7e6818046e7ee1e9c6c91f98aa5ce3113b14fb1c85a50a45569b18NEWRecordBreaker – Raccoon Stealer 2.0
ddae8737d7cc35a87274a26b886e6b48ae947aa849c3d7ecb84de6f6d553aa96NEWRecordBreaker – Raccoon Stealer 2.0
efa9a303af112ffb6737846755e3a995510fd65b6ced9032dc68cd7bbe4c307dNEWRecordBreaker – Raccoon Stealer 2.0
20b5c7f210320cf23a63ac7f76086a6e257dd0c248d77deff444cb3dcf624799NEWRecordBreaker – Raccoon Stealer 2.0
f0ee1ddb789207c2000f728f6adabbe344ded7cba0804926a7cfc53bdbbc54ebNEWRecordBreaker – Raccoon Stealer 2.0
f440309e372551fb6ee00ecca71a70a1b8b7e077fe61b0687411147b582ab415NEWRecordBreaker – Raccoon Stealer 2.0
21a570237cdacdb8c69679e59c4dba6aa05f123f9db7470ec34e2f4024c3646bNEWRecordBreaker – Raccoon Stealer 2.0
4e8bf8c770727a3b0f551adcff2716c941234708e679c868ce42532714a29d27NEWRecordBreaker – Raccoon Stealer 2.0
3c0c55b4ce2d90448949980fbca1fa447832f67fb864472551513b6e4eff5304NEWRecordBreaker – Raccoon Stealer 2.0
61b5b6a513be380d50282c1c8391a5362d746bd70506343d04bda3751c3b25deNEWRecordBreaker – Raccoon Stealer 2.0
a4d455f65bb4d2dde03a0686433b6d515c71b5655fa78b86a4f9bdae503c1295NEWRecordBreaker – Raccoon Stealer 2.0
c9d36fcce70893aa16a846b48009bbd8b46fc11c6821b750083a9c89669038ccNEWRecordBreaker – Raccoon Stealer 2.0
04a1021d0880a4f13ed8693dfe65889a5f827fe5ee9369abbc00b58efc40e69bNEWRedline
13eb08dda92356f21888d95a6611a46728dfcefcdf769e7edad1a70e958e5367NEWRedline
20330ec79f6c6edce8c3d87e3340aebc60f528d3751339e57437b178b9cb914dNEWRedline
22962d59a066795696464868700fa7d3f735bfdb494a7a879fb54668a0ca3d46NEWRedline
2b1be3ea73921adde804b85e93817869556fa9919bf7a528639a796e27351755NEWRedline
301be47a8fefa749d904425b43ae459249e2b44ff62051f3a5529d6222259f42NEWRedline
410b032a8635fba6cc30f0c2049a53f93b98128388a4a7ce2c3a0bfb33591f9fNEWRedline
43d49812cc723b3c24ca7048faa859800c7e303e074243e4348f65d34127367bNEWRedline
47c765ad0baae96498e05e3f0984002cbce6b3f1bacd1cf238681a677c2f8036NEWRedline
482765b55aecbf24eb102f531afb6c8905ab7a058a447d217be70984f15b4573NEWRedline
50b7e742eea52e18cf908cd676b87c0f145ecc3ff9692b01c90c47750fe989a7NEWRedline
70a6d43a56d267aa4fdac5a96722a2ff05e2ac1cc9ba996d173f0b3252e09898NEWRedline
7263336f1ec49f936501c508a9edf072a81002e64e52a1ed0cafb1378bb07a2aNEWRedline
770e7d287fe352f12757ebfbb4502b10f61001630d70ddf414157b12e1f5e9a3NEWRedline
87f5b4385a2a87229b6c448a3b4b19a7e75fe6bc607dffc0e1f860e9e4499ecaNEWRedline
adc5669dd1153111f4cc07714599145a775d8c260c1acae9c142280147d1793aNEWRedline
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e35547cfb6ae3fe18df6d887334952e7a38cc51a230f02c7f62a5fef083de7cfNEWRedline
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fefb4288cb41fcca85cd50653093d7b27c9c51769b03f72adf951c5a1f111ddfNEWRedline
f79273a1efb664d81f68e808b9ec963bfeb79d63bd277108863d6ae3c4801a9eNEWRedline
24c870202b3aedfcd28a8afb93b5212b791c265abd872ef94e44401d1ca309adNEWRedline
417c3f327c2d8b54ec72a5a89280fecb589a3e0b89c281bbc077d7de445cc76bNEWRedline
948416d3aeae6f31df3341118a25a4231a7eed23b3db73a022e9da70734163c9NEWRedline
71cc196ad2103a1facd81f2b8bd985273f682019b2a88841d2f34ecc373d1d69NEWRedline
7bdb945f2dab863a299e26ab4c6dfb1e4f7321c38fe101224252d993495bc157NEWRedline
0bb4d022d6007fcaf1d0707b646063b4b66cf5177da6a1fc6c5d0fc217501d6fNEWRedline
0e918ad3e7ad983ecf6c3238991c13a230acc897193e0ad360d2eeaab42bf078NEWRedline
f413dbf6764bc73ab94428831e0ce3fc0369856aa50c4f9c0f5948eac85d2d08NEWRedline
670a96324222e6bb02bd36c7e5b100fb5d52d2d59891bd9599b1a47438ac9578NEWRedline
9049d536e6da46b63c562197ab92f511d5f5e2883eb8bf29f72217282ae25772NEWRedline
116d81561faa8c8a9cf4fbc947e9eee11185f3960daead8179a968dea143bfd0NEWRedline
9984a21c06fea77e96ba410cffb99de530201ef0c74f3e8b38b3afd4fdf0b333NEWRedline
bcc80eabe068cbbe38fa37b58e67fee54af75fa9e8a1fc30d93b7d30886d05daNEWRedline
202570439b32480e6df232977d5435be9be94822c75f89b09f571e5b03f8c9abNEWRedline
96b5ea21a2556486cebbed76711a8bbae42de1e97e3311213833c6567a4fbbdcNEWRedline
35c53663294e5476315853228b4ae642f552c6c6b1253412a7f981c7ddf3d0b7NEWRemcos
8c451b84d9579b625a7821ad7ddcb87bdd665a9e6619eaecf6ab93cd190cf504NEWRemcos
7d8c18056e86a3b8c32b524f9de009ced61caf463abe1bca285fa305d4b5616aNEWRhadamanthys
a2e9a2389faf04b67fbbd6fc71134860a145db7643d88ba312390493d5619302NEWRhadamanthys
9f96e5bc9ffc9742cb10384566dc7fb232e0f0d633e643bd487b747b6e88f369NEWRhadamanthys
71ecfddc7fe52a10bdf79c39cf9a1d911257ed0deee1bfef21386053bfe88110NEWRhadamanthys
96e49a5ac188d49003b2fe77ad8a4c8866a94cc828dc6172d9a13a8c26e49b9bNEWRhadamanthys
5474d15059ca4213ab1c13fba25ab8ba38559cac7ec2ab336d2411b90eab1217NEWSnakeKeylogger
eb2e2ac0f5f51d90fe90b63c3c385af155b2fee30bc3dc6309776b90c21320f5NEWSnakeKeylogger
02355d3fee5e217b25f9210ad0f6bacc3807b6ef1a59aa4d428c01017dcbcf28NEWVidar
05f9553616bb5fdbf37bd4036c210929e08d7181de898c1bea1bdae7afb0766fNEWVidar
0c857501e3851072db666386136929c06bcf4c8d3160b41b7d82a3ce9afca1beNEWVidar
3418a369486e9bf2b57023dc0b02cb00f12a5214fca8bae20ff93586cc8c678aNEWVidar
363c46dfb252d7c40d9c3bb63bdc40c2eff0ce16c0c1b77f507d73058104c6e1NEWVidar
4c17f7ee55f9bf6fa9acaeeb9574feab39ba4a3cccd4426dfa85aaf58b90ae73NEWVidar
4d4f97f1621334e4075e0229265ac6c5da14754eff1378a7d77ea6d3821e8a33NEWVidar
87b92fcd04f69f9c132c9f350dbb3686888a5e388b1f787f6a658f09582c0da6NEWVidar
99e733391ac499e78e535a98551c4d27408abfad4e56fe4c46956636655df29cNEWVidar
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c6e0a5e947e9f23cd0af6fa8bd44411a12212ab1de5007036926089800ac8692NEWVidar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Yara

rule injector_ZZ_dotRunpeX {
    meta:
        description = "Detects new version of dotRunpeX - configurable .NET injector"
    author = "Jiri Vinopal (jiriv)"
    date = "2022-10-30"
    hash1 = "373a86e36f7e808a1db263b4b49d2428df4a13686da7d77edba7a6dd63790232" // injects Formbook
        hash2 = "41ea8f9a9f2a7aeb086dedf8e5855b0409f31e7793cbba615ca0498e47a72636" // injects Formbook
        hash3 = "5e3588e8ddebd61c2bd6dab4b87f601bd6a4857b33eb281cb5059c29cfe62b80" // injects AsyncRat
        hash4 = "8c451b84d9579b625a7821ad7ddcb87bdd665a9e6619eaecf6ab93cd190cf504" // injects Remcos
        hash5 = "8fa81f6341b342afa40b7dc76dd6e0a1874583d12ea04acf839251cb5ca61591" // injects Formbook
        hash6 = "cd4c821e329ec1f7bfe7ecd39a6020867348b722e8c84a05c7eb32f8d5a2f4db" // injects AgentTesla
        hash7 = "fa8a67642514b69731c2ce6d9e980e2a9c9e409b3947f2c9909d81f6eac81452" // injects AsyncRat
        hash8 = "eb2e2ac0f5f51d90fe90b63c3c385af155b2fee30bc3dc6309776b90c21320f5" // injects SnakeKeylogger
    strings:
    // Used ImplMap imports (PInvoke) 
        $implmap1 = "VirtualAllocEx"
        $implmap2 = "CreateProcess"
        $implmap3 = "CreateRemoteThread"
        $implmap4 = "Wow64SetThreadContext"
        $implmap5 = "Wow64GetThreadContext"
        $implmap6 = "NtResumeThread"
        $implmap7 = "ZwUnmapViewOfSection"
        $implmap8 = "NtWriteVirtualMemory"
        $implmap9 = "MessageBox" // ImplMap not presented in all samples - maybe different versions?
        $implmap10 = "Wow64DisableWow64FsRedirection"
        $implmap11 = "Wow64RevertWow64FsRedirection"
        $implmap12 = "CreateFile"
        $implmap13 = "RtlInitUnicodeString"
        $implmap14 = "NtLoadDriver"
        $implmap15 = "NtUnloadDriver"
        $implmap16 = "OpenProcessToken"
        $implmap17 = "LookupPrivilegeValue"
        $implmap18 = "AdjustTokenPrivileges"
        $implmap19 = "CloseHandle"
        $implmap20 = "NtQuerySystemInformation"
        $implmap21 = "DeviceIoControl"
        $implmap22 = "GetProcessHeap"
        $implmap23 = "HeapFree"
        $implmap24 = "HeapAlloc"
        $implmap25 = "GetProcAddress"
        $implmap26 = "CopyMemory" // ImplMap added by KoiVM Protector used by this injector
        $modulerefKernel1 = "Kernel32"
        $modulerefKernel2 = "kernel32"
        $modulerefNtdll1 = "Ntdll"
        $modulerefNtdll2 = "ntdll"
        $modulerefAdvapi1 = "Advapi32"
        $modulerefAdvapi2 = "advapi32"

        $regPath = "\\Registry\\Machine\\System\\CurrentControlSet\\Services\\TaskKill" wide // Registry path for installing Sysinternals Procexp driver
        $rsrcName = "BIDEN_HARRIS_PERFECT_ASSHOLE" wide
        $koiVM1 = "KoiVM"
        $koiVM2 = "#Koi"
    condition:
        uint16(0) == 0x5a4d and uint16(uint32(0x3c)) == 0x4550 and ($regPath or $rsrcName or 1 of ($koiVM*)) and
        24 of ($implmap*) and 1 of ($modulerefKernel*) and 1 of ($modulerefNtdll*) and 1 of ($modulerefAdvapi*) 

}
rule injector_ZZ_dotRunpeX_oldnew {
	meta:
		description = "Detects new and old version of dotRunpeX - configurable .NET injector"
    author = "Jiri Vinopal (jiriv)"
    date = "2022-10-30"
    hash1_New = "373a86e36f7e808a1db263b4b49d2428df4a13686da7d77edba7a6dd63790232" // injects Formbook
		hash2_New = "41ea8f9a9f2a7aeb086dedf8e5855b0409f31e7793cbba615ca0498e47a72636" // injects Formbook
		hash3_New = "5e3588e8ddebd61c2bd6dab4b87f601bd6a4857b33eb281cb5059c29cfe62b80" // injects AsyncRat
		hash4_New = "8c451b84d9579b625a7821ad7ddcb87bdd665a9e6619eaecf6ab93cd190cf504" // injects Remcos
		hash5_New = "8fa81f6341b342afa40b7dc76dd6e0a1874583d12ea04acf839251cb5ca61591" // injects Formbook
		hash6_New = "cd4c821e329ec1f7bfe7ecd39a6020867348b722e8c84a05c7eb32f8d5a2f4db" // injects AgentTesla
		hash7_New = "fa8a67642514b69731c2ce6d9e980e2a9c9e409b3947f2c9909d81f6eac81452" // injects AsyncRat
		hash8_New = "eb2e2ac0f5f51d90fe90b63c3c385af155b2fee30bc3dc6309776b90c21320f5" // injects SnakeKeylogger
		hash1_Old = "1e7614f757d40a2f5e2f4bd5597d04878768a9c01aa5f9f23d6c87660f7f0fbc" // injects Lokibot
		hash2_Old = "317e6817bba0f54e1547dd9acf24ee17a4cda1b97328cc69dc1ec16e11c258fc" // injects Redline
		hash3_Old = "65cac67ed2a084beff373d6aba6f914b8cba0caceda254a857def1df12f5154b" // injects SnakeKeylogger
		hash4_Old = "68ae2ee5ed7e793c1a49cbf1b0dd7f5a3de9cb783b51b0953880994a79037326" // injects Lokibot
		hash5_Old = "81763d8e3b42d07d76b0a74eda4e759981971635d62072c8da91251fc849b91e" // injects SnakeKeylogger
	strings:
	// Used ImplMap imports (PInvoke) 
		$implmap1 = "VirtualAllocEx"
		$implmap2 = "CreateProcess"
		$implmap3 = "CreateRemoteThread"
		$implmap4 = "Wow64SetThreadContext"
		$implmap5 = "Wow64GetThreadContext"
		$implmap6 = "RtlInitUnicodeString"
		$implmap7 = "NtLoadDriver"
		$implmap8 = "LoadLibrary"
		$implmap9 = "VirtualProtect"
		$implmap10 = "AdjustTokenPrivileges"
		$implmap11 = "GetProcAddress"
		$modulerefKernel1 = "Kernel32"
		$modulerefKernel2 = "kernel32"
		$modulerefNtdll1 = "Ntdll"
		$modulerefNtdll2 = "ntdll"

		$regPath = "\\Registry\\Machine\\System\\CurrentControlSet\\Services\\TaskKill" wide // Registry path for installing Sysinternals Procexp driver
		$rsrcName = "BIDEN_HARRIS_PERFECT_ASSHOLE" wide
		$koiVM1 = "KoiVM"
		$koiVM2 = "#Koi"
	condition:
		uint16(0) == 0x5a4d and uint16(uint32(0x3c)) == 0x4550 and ($regPath or $rsrcName or 1 of ($koiVM*)) and
		9 of ($implmap*) and 1 of ($modulerefKernel*) and 1 of ($modulerefNtdll*) 
}

References

  1. KoiVM protector: https://github.com/yck1509/KoiVM
  2. Reflection in .NET: https://learn.microsoft.com/en-us/dotnet/framework/reflection-and-codedom/reflection
  3. P/Invoke: https://learn.microsoft.com/en-us/dotnet/standard/native-interop/pinvoke
  4. D/Invoke: https://github.com/TheWover/DInvoke
  5. Backstab: https://github.com/Yaxser/Backstab
  6. MinHook: https://github.com/TsudaKageyu/minhook
  7. ClrMD: https://github.com/microsoft/clrmd
  8. AsmResolver: https://github.com/Washi1337/AsmResolver
  9. OldRod: https://github.com/Washi1337/OldRod

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