Threat Encyclopedia

BKDR_ZACESS.SMQQ

Publish date: October 27, 2012

ANALYSIS BY

Rhena Inocencio


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, Downloaded from the Internet


This backdoor terminates processes which can compromise system security. It also patches a file that subsequently becomes malicious.

This backdoor arrives via peer-to-peer (P2P) shares. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be dropped by other malware.

It connects to a website to send and receive information.

TECHNICAL DETAILS

File Size:

192,512 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

06 Jul 2012

Payload:

Connects to URLs/IPs, Terminates processes, Patches files

Arrival Details

This backdoor arrives via peer-to-peer (P2P) shares.

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

It may be dropped by the following malware:

  • BKDR_ZACCESS.KP

Autostart Technique

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

HKEY_CURRENT_USER\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\
InprocServer32
ThreadingModel = "Both"

HKEY_CURRENT_USER\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\
InprocServer32
(Default) = "%Application Data%\{GUID}\n."

Other System Modifications

This backdoor modifies the following registry entries:

HKEY_CLASSES_ROOT\CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\
InprocServer32
(Default) = "\.\globalroot\systemroot\Installer\{GUID}\n."

(Note: The default value data of the said registry entry is %System%\wbem\wbemess.dll.)

Backdoor Routine

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

  • http://{BLOCKED}s.{BLOCKED}g.com

Process Termination

This backdoor terminates the following processes if found running in the affected system's memory:

  • MsMpSvc
  • windefend
  • SharedAccess
  • iphlpsvc
  • wscsvc
  • mpssvc
  • bfe
  • SecurityCenter
  • Wscnotify.exe
  • MSASCui.exe
  • MpCmdRun.exe
  • MisSrv.exe
  • msseces.exe
  • wsctfy.exe

Other Details

This backdoor requires the existence of the following files to properly run:

  • %User Temp%\InstallFlashPlayer.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

NOTES:

It connects to its C&C server using UDP connection.

It is a .DLL file, which is executed by %User Temp%\InstallFlashPlayer.exe.

It patches %System%\services.exe and saves the original copy in %System%\Winsxs\Backup\services.exe.

  • Patched 64-bit %System%\services.exe - detected as PTCH64_ZACCESS.A
  • Patched Win7 32-bit %System%\services.exe - detected as PTCH_ZACCESS.A

The modified registry ensures that the malware is loaded instead of %System%\wbem\wbemess.dll, which is related to Web Browser Control.

The following files, which are dropped by the main malware BKDR_ZACCESS.KP, are used by BKDR_ZACESS.SMQQ in registry entries to enable automatic execution of the malware at every system startup:

  • %Application Data%\{GUID}\n.
  • \.\globalroot\systemroot\Installer\{GUID}\n.

where \.\globalroot\systemroot is equivalent to %Windows%

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.240.07

FIRST VSAPI PATTERN DATE:

06 Jul 2012

VSAPI OPR PATTERN File:

9.241.00

VSAPI OPR PATTERN Date:

06 Jul 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_ZACESS.SMQQ

Step 3

Remove the malware/grayware file that dropped/downloaded BKDR_ZACESS.SMQQ

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Restore this modified 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_CLASSES_ROOT\CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\InprocServer32
    • From: (Default)  = "\.\globalroot\systemroot\Installer\{GUID}\n."
      To: (Default) = "%System%\wbem\wbemess.dll"

Step 6

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_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\InProcServer32
    • ThreadingModel = "Both"
  • In HKEY_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\InProcServer32
    • (Default) = "%Application Data%\{GUID}\n."

Step 7

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

NOTES:
Please perform this step before proceeding to Step 7:

  • Move services.exe from %System%\Winsxs\Backup to %System%


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