Analysis by: Mark Joseph Manahan
ALIASES:

VirTool:Win32/Obfuscator.WU, Trojan:Win32/Simda.R (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan is used by BKDR_SIMDA.SU for elevating privileges in a 32-bit environment.

This Trojan may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 20,993 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 27 Aug 2012

Arrival Details

This Trojan may be dropped by the following malware:

  • BKDR_SIMDA.SU

NOTES:

This Trojan is used by BKDR_SIMDA.SU for elevating privileges in a 32-bit environment. It allows backdoor execution without displaying any security warning usually done via the Windows feature User Account Control (UAC) by using the following native API calls:

  • ZwAcceptConnectPort
  • ZwClose
  • ZwCompleteConnectPort
  • ZwCreateSection
  • ZwCreateWaitablePort
  • ZwReplyPort
  • ZwReplyWaitReceivePort

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.350.04
FIRST VSAPI PATTERN DATE: 27 Aug 2012
VSAPI OPR PATTERN File: 9.351.00
VSAPI OPR PATTERN Date: 27 Aug 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 the malware/grayware file that dropped/downloaded TROJ_SIMDA.SU

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_SIMDA.SU

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete the file detected as TROJ_SIMDA.SU

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 6

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