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Android.Triada.4912

Added to the Dr.Web virus database: 2021-03-25

Virus description added:

SHA1 hashes:

  • 3e7e5de03e1e1cb472703602d5f8296e7aec3239 (the first modification discovered on 25.03.2021)
  • 1d97a5ba869526433d09f315c4bb1c66dac7dddd (a modification discovered on 02.04.2021)
  • 2ea82dcc114b75ce09a37a8f1b07675ca528d7c9 (an arm version, actual at the time of the analysis)
  • a6490426bc4c94a70225285b94120c49b10e62d8 (x86 version, actual at the time of the analysis)

Description

An Android trojan built into the official APKPure catalog client software version 3.17.18. Its main functionality is to execute the malicious module hidden inside it. This module downloads other trojan components and loads various websites.

Operating routine

Android.Triada.4912 utilizes various techniques to protect itself from the analysis. Its code contains multiple garbage strings and has a large number of calls through the reflection. Moreover, the names of the methods and classes called through the reflection, as well as the strings of the malware are encrypted with an XOR operation with the d4as56fads4f4 key, and also in Base64.

The initialization of the trojan occurs in the ZcoupSDK class. For that, the following string is added to the initInternal method:

W1a3s4t9B0.Go(arg5.getApplicationContext(), "2021-3-22-ssk015-ym2", null, 1);

For comparison, the image below shows the corresponding code fragments of the trojanized version of the APKPure application and its original version:

#drweb

The Android.Triada.4912 decrypts a payload (Android.Triada.566.origin) from the hardcoded string, placing the payload to the /files/*package_name*_s/ directory. It also decrypts the name of the main class of this malicious module, which is com.bb.s2x2e.go.AAA. After the successfully decrypting the payload, the trojan executes the initMe in it and loads the payload into the RAM.

In Android.Triada.4912, calls for the following methods from the payload are implemented through reflection:
  • initMe
  • readData
  • delayTime
  • clickTime
  • closeTime
  • count
  • chanEanble
  • time
  • setPackageName
  • setSourceDir
  • setPublicSourceDir
  • getFBApk

News about the trojan

Curing recommendations


Android

  1. If the mobile device is operating normally, download and install Dr.Web for Android Light. Run a full system scan and follow recommendations to neutralize the detected threats.
  2. If the mobile device has been locked by Android.Locker ransomware (the message on the screen tells you that you have broken some law or demands a set ransom amount; or you will see some other announcement that prevents you from using the handheld normally), do the following:
    • Load your smartphone or tablet in the safe mode (depending on the operating system version and specifications of the particular mobile device involved, this procedure can be performed in various ways; seek clarification from the user guide that was shipped with the device, or contact its manufacturer);
    • Once you have activated safe mode, install the Dr.Web для Android Light onto the infected handheld and run a full scan of the system; follow the steps recommended for neutralizing the threats that have been detected;
    • Switch off your device and turn it on as normal.

Find out more about Dr.Web for Android