Modified by: Rika Joi Gregorio
ALIASES:

Trojan:Win32/Droidpak.A(Microsoft), Trojan.Droidpak(Symantec), Trojan.Win32.AndrFakeBankDl(Ikarus)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This is a malware that downloads and installs malicious apps onto any Android device connected to the affected PC. The apps are malicious versions of online banking apps, which could compromise a user’s online banking account.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 82,432 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Jan 2014
Payload: Connects to URLs/IPs

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following files:

  • %System%\flashmx32.xtl - also detected as TROJ_DROIDPAK.A
  • %Windows%\CrainingApkConfig\down.log

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Windows% is the Windows folder, which is usually C:\Windows.)

Its DLL component is injected to the following process(es):

  • svchost.exe

It creates the following folders:

  • %Windows%\CrainingApkConfig

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

This Trojan registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx
ImagePath = "%System%\svchost -k flashmx"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx
DisplayName = "Object Update Monitor"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx
Description = "Service for adobe client product"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx\Parameters
ServiceDll = "%System%\flashmx32.xtl"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\flashmx\Parameters

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
flashmx = "flashmx"

Download Routine

This Trojan connects to the following URL(s) to download its configuration file:

  • http://xia2.{BLOCKED}-web.com/iconfig.txt

It saves the files it downloads using the following names:

  • %Windows%\CrainingApkConfig\iconfig.txt

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

As of this writing, the said sites are inaccessible.

Other Details

This Trojan deletes itself after execution.

NOTES:

The file %Windows%\CrainingApkConfig\iconfig.txt may contain strings that this malware appends to http://xia2.{BLOCKED}web.com/ to download arbitrary files. It saves the downloaded file in the same folder where it uses the string from the configuration file as its file name. Based on code analysis, the file iconfig.txt may contain the following strings:

  • AV-cdk.apk
  • adb.exe

This malware also uses ADB.EXE to install the downloaded .APK file to Android devices connected to the machine.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.572.03
FIRST VSAPI PATTERN DATE: 29 Jan 2014
VSAPI OPR PATTERN File: 10.573.00
VSAPI OPR PATTERN Date: 30 Jan 2014

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • flashmx

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • flashmx = "flashmx"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Windows%\CrainingApkConfig

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROIDPAK.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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