Analysis by: Mark Joseph Manahan
ALIASES:

Troj/Inject-AVF (Sophos) ,Trojan horse Generic35.BYVV (AVG) ,W32/Inject.AVF!tr (Fortinet) ,Trojan.Win32.Inject.ihsh (Kaspersky) ,Trojan-FDTJ!23A3DCE113D7 (McAfee) ,a variant of Win32/TrojanDropper.Agent.QNB trojan (Eset) ,Trojan Horse (Symantec) ,Generic (Panda) ,Trojan.Win32.Generic!BT (Sunbelt)

 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: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This backdoor may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 152,064 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Apr 2013

Arrival Details

This backdoor may be dropped by other malware.

Installation

This backdoor drops the following file(s)/component(s):

  • %User Temp%\tmp.dat - TROJ_SIMBOTENC.ZTBD-R
  • %User Temp%\tmp.dll - TROJ_SIMBOTLDR.ZTBD-R
  • %User Temp%\lscript.dll - log

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following copies of itself into the affected system:

  • %User Profile%\Local Settings\WinHttp.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
WinHttp = "%User Profile%\Local Settings\WinHttp.exe"

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.760.06
FIRST VSAPI PATTERN DATE: 29 Apr 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

Remove malware/grayware files dropped/downloaded by BKDR_SIMBOTDRP.ZTBD-R. (Note: Please skip this step if the threats listed below have already been removed.)

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • WinHttp = "%User Profile%\Local Settings\WinHttp.exe"

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\lscript.dll - log

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SIMBOTDRP.ZTBD-R. 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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