Modified by: Sabrina Lei Sioting

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • 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.

It scans the computer for registry keys related to antivirus and security applications. This action allows the malware to possibly avoid detection in the computer.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: 36,864 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 18 Apr 2012
Payload: Compromises system security, Connects to URLs/IPs

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_ARTIEF.FT

Installation

This backdoor drops the following copies of itself into the affected system:

  • %User Profile%\Local Settings\{random}.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
{random} = "%User Profile%\Local Settings\{random}.exe"

Other System Modifications

This backdoor scans the system for the following registry keys, which are related to antivirus and security applications:

HKEY_LOCAL_MACHINE\SOFTWARE\McAfee

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download and execute files
  • Execute a DOS command sent by the remote user
  • Send an encrypted copy of the content of a specified file to its C&C server
  • Sleeps for a specified amount of time

It connects to the following websites to send and receive information:

  • {BLOCKED}.103.58

NOTES:

If the registry, HKEY_LOCAL_MACHINE\SOFTWARE\McAfee is found on the system, it adds the following process:

  • services.exe

It then injects itself into the said process as part of its memory residency routine.

If the registry is not found, it adds the following process:

  • svchost.exe

It injects itself into that process as part of its memory residency routine.

It communicates with its C&C server by sending the following HTTP request:

  • http://{C&C}/{random characters}.php?id={encoded adapter information of the affected machine}

The {random} file name of dropped copy/registry value name above can be any of the inactive services on the system.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.920.03
FIRST VSAPI PATTERN DATE: 18 Apr 2012
VSAPI OPR PATTERN File: 8.921.00
VSAPI OPR PATTERN Date: 19 Apr 2012

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 that dropped/downloaded BKDR_SIMBOT.SME

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
    • {random} = %User Profile%\Local Settings\{random}.exe

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SIMBOT.SME. 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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