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BKDR_SIMBOT.TRWU

November 17, 2014
 PLATFORM:

Windows

 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:

Downloaded from the Internet, Dropped by other malware


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

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

It terminates itself if it detects it is being run in a virtual environment.

  TECHNICAL DETAILS

File Size:

73,709,568 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Nov 2014

Payload:

Compromises system security, Connects to URLs/IPs, Steals information

Arrival Details

This backdoor 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 backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • #$#$SDOIRES

It injects codes into the following process(es):

  • It injects embedded DLL component (also detected as BKDR_SIMBOT.TRWU) to svchost.exe

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
ImagePath = ""%System%\greprun.exe" -k"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
DisplayName = "Device Enumerator Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service
Description = "Enables applications to transfer and synchronize content using removable mass-storage devices."

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service\Security

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Device Enumerator Service\Enum

It adds the following registry entries:

HKEY_LOCAL_MACHINE\Software\AppDataLow\
Software\Microsoft\svchost
BinData = "{encrypted C&Cs}"

Backdoor Routine

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

  • Download and execute files

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

  • http://{BLOCKED}3.{BLOCKED}9.214.216/ppmadmin/themes/pmahomme/ana.php
    It posts information with the following format: VerInfo={base 64 encoded IP address and computer name}

It posts the following information to its command and control (C&C) server:

  • MAC address
  • IP address
  • Computer name

As of this writing, the said servers are currently inaccessible.

Other Details

This backdoor terminates itself if it detects it is being run in a virtual environment.

NOTES:

It checks if it is running under the following virtual environment:

  • VMWare
  • VirtualBox

If it is running under the above mentioned environments, it terminates itself without doing its intended routine.

  SOLUTION

Minimum Scan Engine:

9.700

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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
    • Device Enumerator Service

Step 5

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\AppDataLow\Software\Microsoft\svchost
    • BinData = "{encrypted C&Cs}"

Step 6

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