Analysis by: Sabrina Lei Sioting
 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

Infection Channel: Dropped by other malware, Downloaded from the Internet

This Trojan connects to certain URLs to send and receive commands from a remote malicious user. It terminates processes, some of which are related to system security.

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

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 185,856 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Sep 2012
Payload: Drops files, Connects to URLs/IPs, Terminates processes, Compromises system security

Arrival Details

This Trojan 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 Trojan injects itself into the following processes running in the affected system's memory:

  • svchost.exe

It creates the following folders:

  • %Windows%\$NtUninstallKB34902$\2349794393\
  • %Windows%\$NtUninstallKB34902$\2349794393\L
  • %Windows%\$NtUninstallKB34902$\2349794393\U

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Other System Modifications

This Trojan deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\BITS

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv

Dropping Routine

This Trojan drops the following files:

  • %Windows%\$NtUninstallKB34902$\2349794393\Desktop.ini - detected as TROJ_SIREFEF.AEL
  • %Windows%\$NtUninstallKB34902$\2349794393\U\00000004.@ - detected as TROJ_ZEROA.SM3
  • %Windows%\$NtUninstallKB34902$\2349794393\U\00000008.@ - detected as TROJ_DROPR.ZA
  • %Windows%\$NtUninstallKB34902$\2349794393\U\000000cb.@ - detected as TROJ_SIREFEF.DAM
  • %Windows%\$NtUninstallKB34902$\2349794393\U\80000000.@ - detected as TROJ_ZEROA.SM1

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Other Details

This Trojan deletes itself after execution.

NOTES:

It accesses the following site to know its location:

  • http://{BLOCKED}ling.com/geo/txt/city.php

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.428.06
FIRST VSAPI PATTERN DATE: 29 Sep 2012
VSAPI OPR PATTERN File: 9.429.00
VSAPI OPR PATTERN Date: 29 Sep 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 TROJ_SIREFEF.SZP

    • TROJ_SIREFEF.AEL
    • TROJ_ZEROA.SM3
    • TROJ_DROPR.ZA
    • TROJ_SIREFEF.DAM
    • TROJ_ZEROA.SM1

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Windows%\$NtUninstallKB34902$\2349794393\
  • %Windows%\$NtUninstallKB34902$\2349794393\L
  • %Windows%\$NtUninstallKB34902$\2349794393\U

Step 5

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

Step 6

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BITS
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wscsvc
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv


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