Clast82 – A new Dropper on Google Play Dropping the AlienBot Banker and MRAT

March 9, 2021

Research by: Aviran Hazum, Bohdan Melnykov, Israel Wernik

Check Point Research (CPR) recently discovered a new Dropper spreading via the official Google Play store, which downloads and installs the AlienBot Banker and MRAT.
This Dropper, dubbed Clast82, utilizes a series of techniques to avoid detection by Google Play Protect detection, completes the evaluation period successfully, and changes the payload dropped from a non-malicious payload to the AlienBot Banker and MRAT.
The AlienBot malware family is a Malware-as-a-Service (MaaS) for Android devices that allows a remote attacker, at a first step, to inject malicious code into legitimate financial applications. The attacker obtains access to victims’ accounts, and eventually completely controls their device. Upon taking control of a device, the attacker has the ability to control certain functions just as if he was holding the device physically, like installing a new application on the device, or even control it with TeamViewer.

Figure 1 – Clast82 Malware on Google Play

General

This malware, dubbed CLAST82, used a series of techniques to avoid detection by Google Play Protect:

  • Using Firebase as a platform for C&C communication
  • Using GitHub as a 3rd party hosting platform to download the payload from

During the Clast82 evaluation period on Google Play, the configuration sent from the Firebase C&C contains an “enable” parameter. Based on the parameter’s value, the malware will “decide” to trigger the malicious behavior or not. This parameter is set to “false” and will only change to “true” after Google has published the Clast82 malware on Google Play.

Figure 2 – “Disabled” configuration sent from the Firebase C&C

Figure 3 – “Enabled” configuration sent from the Firebase C&C

 

The malware’s ability to remain undetected demonstrates the importance of why a mobile security solution is needed. It’s not enough to scan the app during the evaluation period, as a malicious actor can, and will change the applications behavior while using 3rd party tools. A solution that monitors the device itself, constantly scanning network connections and behaviors by application will be able to detect such behavior. Furthermore, the payload dropped by Clast82 does not originate from Google Play, thus the scanning of applications before submission to review will not prevent the installation of the malicious payload.

The Campaign

During our investigation of the Clast82 Dropper, we uncovered the infrastructure used by the actor for distributing and maintaining the campaign. For each application, the actor created a new developer user for the Google Play store, along with a repository on the actor’s GitHub account, thus allowing the actor to distribute different payloads to devices that were infected by each malicious application.

Figure 4 – The Actor’s GitHub Repositories

While looking into the fake developer accounts on Google Play belonging to the actor, we came across another commonality – the Developer email for all apps is the same email ‘[email protected]’, and the links to each application for the Privacy Policy page links to the same repository, also belonging to the same actor. (https://gohhas.github.io/<app-name>)

                                                                                     

Figure 5 – Developer email and Privacy Policy Links

Figure 6 – GitHub status for the ‘Gohhas’ account

Figure 7 – Clast82’s campaign attack flow

 

Technical Analysis – Clast82

The actor used legitimate and known open sources android applications, which the actor added the malicious code into in order to provide functionality to the malicious dropper, along with the reason for the victim to download and install it from the official Google Play store. For instance, the malicious CakeVPN application is based on this GitHub repository.
On every application launch, it starts a service from MainActivity that starts a dropping flow called LoaderService. In addition, the MainActivity starts a foreground service to perform the malicious dropping task.
To comply with the Android restrictions, when an application creates a foreground service, it must also show an on-going notification to the user. Clast82 bypassed this by showing a “neutral” notification. In the case of the patient-zero, the CakeVPN app, the notification shown is “GooglePlayServices” with no additional text.

Figure 8 – calling the LoaderService from the OnCreate function

 

Figure 9 – The on-going notification hadling for Clast82

Figure 10 – the on-going notification sent my Clast82

The foreground service registers a listener for the Firebase real-time database, from which it receives the payload path from GitHub

Figure 11 – The communication with the Firebase C&C

 

Figure 12 – Pasring the Firebase data

After receiving the command from the Firebase C&C, the dropping flow starts with the ‘loadAndInstallApp’ function, which downloads the payload from GitHub, and calls the ‘installApp’ method to finalize the malicious activity.

Figure 13 – The loadAndInstallApp method

 

Figure 14 – The installApp method

If the infected device prevents installations of applications from unknown sources, Clast82 prompts the user with a fake request, pretending to be ‘Google Play Services’ requesting the user to allow the installation every 5 seconds.

 

Figure 15 – Fake prompt to user

 

After the malicious payload is successfully installed, the dropper app launches the payload downloaded. In the case of Clast82, we were able to identify over 100 unique payloads of the AlienBot, an Android MaaS Banker (Malware as a service) targeting financial applications and attempting to steal the credentials and 2FA codes for those applications.

Figure 16 – Execution of the malicious payload

Timeline

January 27th – Initial discovery

January 28th – Report to Google

February 9th – Google confirmed that all Clast82 apps were removed from the Google Play Store.

 

How to protect yourself

Harmony Mobile (formerly known as SandBlast Mobile) delivers complete protection for the mobile workforce by providing a wide range of capabilities that are simple to deploy, manage and scale. Harmony Mobile provides protection for all mobile vectors of attack, including the download of malicious applications and applications with malware embedded in them.

Learn more:

Appendix 1 – IOCs

C&C Servers:

  • boloklava87[.]club
  • enegal-23[.]net
  • balabanga90[.]online
  • dsfikj2dsfmolds[.]top
  • blakarda[.]site
  • sponkisn[.]site

Droppers:

name
sha256
package_name
Firebase account
Payload URL
Cake VPN
52adb34cc01aa8d034d71672f3efe02c8617641ee77bf6c5eb6806e834550934
com.lazycoder.cakevpns
https://cake-vpn-811be-default-rtdb.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/none.apk
Pacific VPN
bb49fc80393647d379a8adc8d9dec2f9a21e86620ee950f94cdc341345df459c
com.protectvpn.freeapp
https://pacificvpn.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/coon.apk
eVPN
232d3a2a172db5d0e02570a8ddbb8377dc5b8507aab85a51faf00631b51b7def
com.abcd.evpnfree
https://evpn-e7e0d.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/noon.apk
BeatPlayer
609350daaadee74e6526dee7f533affdbf289f076837a2400017a928531c3da1
com.crrl.beatplayers
https://beat-player-763d3-default-rtdb.firebaseio[.]com
Not enabled
BeatPlayer
804fb97dbe7dc93f7ed37963f120ef5f5f7e6253501bd60f08433b0fd5c3db74
com.crrl.beatplayers
https://beat-player-763d3-default-rtdb.firebaseio[.]com
Not enabled
QR/Barcode Scanner MAX
82ea6fc0f57ae82cf7c51a039b6dee7b81b4ece0579a784ee35f02e71b833f3e
com.bezrukd.qrcodebarcode
https://qrscanner-aa57d.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/coon.apk
eVPN
80a4380b812df71401733b0b37005e82a96f18b07be5317e82f38658b1551c5a
com.abcd.evpnfree
https://evpn-e7e0d.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/noon.apk
Music Player
6f6c16481c0f3a4bd3afcaa9aa881e569c65e067c09efd4ac4828ead29242c95
com.revosleap.samplemusicplayers
https://sample-music-player-default-rtdb.firebaseio[.]com
Not enabled
tooltipnatorlibrary
bbe2e4a68eb2a2589b6b7ba9afefd241f8eb6d8db6fa19fdd4d383311a019567
com.mistergrizzlys.docscanpro
https://docscan-3f3c1-default-rtdb.firebaseio[.]com
https://github[.]com/skinner222/grace/raw/main/boost.apk
QRecorder
4d4f8acda2e9b430d5f3a175dbeee9dfcd07a9f26332b1a0b9e94166b1bc077f
com.record.callvoicerecorder
https://qrecordernew-default-rtdb.firebaseio[.]com
https://github[.]com/clast82/publick/raw/main/brain.apk

AlienBot Payloads:

  • 231b5337e561e197775c7250ed3f82bcc0bbdde059ffff1012c672cd7126c13d
    e0ac33e9c0bd5a33959faf3eb40ca95b7a5c8bd6b6eb5a916085a05366643089
  • 08334829f9c1b7db50acc38129ce2e001c928772a996663a875e27bd7a0d54e2
  • 277dc754cf28a3f0c4a734e84ccdd0fe2b149ff030eaf5c714e8915e95b436d0
  • 51a715475e58ba225c9d031c282f1394531e7e71ab1006e03e303db2afadfdd6
  • 74f0794705b069e75bdc9bbc40b46fea6fefc5a493c36a433eea09971d207f3c
  • 92524a2a0832196524b3daa55726f3c1b62d09cf7997c470405ac138a329ec80
  • 3c1c2ccd34abc145cc6a3d1eb789c499eea530962609acab62c5e6ab3607da66
  • 549a1a1dbb8ca26c38a4e02402cdca272d0af70a8708d50cdc82ade501b5d696
  • 388b525689700638568d3e0f62512dd9293a37253cac8d836a7d1edb3c2bb881
  • 57377c13a08bd0c4376c93fe6f70e9e1779e9801bb22ef85b9f8c31a96a905ee
  • cff15bc6a6012dbed17754d8fa1f50debe52f28e03aa3a0abbdd6674e7752e5c
  • f87469076b856543c22a3e7e1a617e7741208be251cf5d7a5cf0dddc97a86547
  • 8c0a2a34fb7753a3b1c86451cbc9c8c8205164e5942f8068b3edc3f22b13a27a
  • fea918c0f673a1c11d52c7d30c5e858f8521b0ea1827eba1801d6aec93300db0
  • 7aaf4937c9694708b442a2054ef6118db37b857ee0b4d70255dec1012e14e3ea
  • 7a44ead8a55a43c91cb1fc0e21fbf7e3ea58a135d438f37a14065c5f850ad996
  • 9981581da2d34f8101d937ab61d7bf8ec4c441d39487135100b8b5228687c36a
  • dc49b51d2eaacfd1568e0385eca386ce849d72533dfcf449f04510d2558bbbed
  • d5a6ae36bf90f00dd99354b1392a56433d3532b47e18a596683d4ae6c77d5a9f
  • ef5316fc8dee0cea24cff320926943ab24a410651053c54b792ad1d20db6d800
  • 5810af063e1d6c40c96dbc59ba9f702bda2aa6b4c337a8b2ad983314575fc491
  • d6060046f98abd5ab0a89c64aca36a26926d220acd4658eb0c59b736b357c819
  • 0556762d4e843e298b63057cc28ad0c7be0721505502587303c674550473bd50
  • ef2e757973e6e532ec5c3fdca4e40cf554ac0dd4f2e0d2d12f95302dc692cf99
  • c0b1f73f18a45e34fac15c30de6d879a35bf6db4281278c509a9b7a2b7b37bbc
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  • 86b69db3571435a98e8bb94f8fe247c95ecf9e4cb18c9c702f0d3dcd91bb6634
  • 94c5ecf16bbf1cba3fe536e287803d345a056fd96c3e3a997aaf5859c274ee45
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  • d1a6a78f9886503c963bacbfcf5143b9be82ca4b2bb03ab18fe236706df0b874
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  • d1dd759e210e08d10679cd794df94d3ce6b87c5312441a8ee622b69b315f6d03
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  • 55c0b443858cedebf87316b45618e1dc3ef3ad4ace873718aac692b9f28fbeb7
  • 7296cee58dc8b31af03c9efa14b4160dd4c4e9054b2dc1310f2ff1b6fa94cd27
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  • 41aecb150e9f1250c5953e87f2e470cb0a18c74b7387414cee503690de2dec13
  • 6c96461480bfa5bea4d4a7ae3b5718b89697785fea835077e8031405bebb5a87
  • 88c976e37f5efb01987f010488b54670723e3886b064b979166f24c72519c015
  • ab9b5877e00d656725272704554fba587eded3c4258a4b95e74655f147d3766d
  • 8a1cc427d6d235f2bdb415671c66375206f941ba70c5521507d498e448006305
  • 328cfa7bac115ff328c6d0c4714483d95d6a32e0a3e94178b247c0db38f8a0f2
  • 596117ba1f4aec95e5f6e9c055242c24c580d947b864ddccc08f3c7bef856dd7
  • d4f18450c6174dcef50b1a25bb866282fd06936afc6a35f8a161d3a450147935
  • a3e1fb6f041e3745753c48d92db105796fbad58ff307aee442f845837f2c3ae5
  • f1613ab80dff1b78b797dec467415a3d49ce87388ebcd579b24aba28e8c778e5
  • 1a458c210458fcdbeec740acdb0ad07e1c7c3ad1c7bac4139e4ebd632552e062
  • 27e552045d3ad74e36d20c47357ee62795b7776457f62e2a8ebbf1901bd47a5b
  • a7608c803368b3cecd7f129a0f9abddd398808759792426e1dbe4c14972e9ef6
  • 5b9f5cc0373e6682a652b695357e49b1c017697fc6c3ec06db2b4a1001dbfd81
  • 7ff23d2ff8650809bb37718c64b8e3d8ce7124a5ca0108ff4260489111f5b055
  • f644c86a18173bdccc675518a3860ee3c0559dedd3460dcf2629d032f844a107
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  • 28dfbda454017a747c5933b7e7bfc3401259ade55c4627023d49bf8a9e62cd17
  • 4df560e827f5cc1c4608f16ee15cf559ef0e1c51fca19ed2fd15fe7af8f36479
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  • 16e93127b971ce7c297e8737dd5f465b8f2ee0cf62e1dbf0354837c9c1b1c602
  • a36570f1aecdd908cfb3d0cd204299b8e2ab4fe94004707b18706213585fce7e
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  • c661cf935158161d4fa4b201302bb18d613cd9fd8594bd9a0ab312c710f0d053
  • 12bf98fc0fa30602819530ef19f5c0c9c14c781c031ab41add54cf0121c77aac
  • bebad63feb0966038bc5e59581742b088c34f693f02af4ddd9bf9c3946992284
  • 879e8a845c3ef895c4e53ea46f2efa7fdd8c3375166c2036b9bbc8c3876df705
  • a020b2764ce99964d85061675e30da40a6dae09243adc71fc135529bb036e8d5
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