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BKDR_SIMBOT.AO

October 09, 2012
 Modified by: Roland Marco Dela Paz
 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 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:

10 Apr 2012

Payload:

Compromises system security, Connects to URLs/IPs

Arrival Details

This backdoor may be dropped by the following malware:

  • JS_DROPSIM.A

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:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It adds the following processes:

  • svchost.exe

It injects itself into the following processes as part of its memory residency routine:

  • svchost.exe

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

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}.{BLOCKED}.198.176
  • {BLOCKED}.{BLOCKED}.202.124
  • {BLOCKED}y.eso.tw

NOTES:

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}

It is capable of executing the following commands:

  • Download and execute file(s)
  • 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

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:

8.904.04

FIRST VSAPI PATTERN DATE:

11 Apr 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by BKDR_SIMBOT.AO

     JS_DROPSIM.A

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.AO. 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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