Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Qhost.HB (Microsoft), W32/MoonBlk.AA!tr (Fortinet)

 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: Downloaded from the Internet

This Trojan may be downloaded by other malware/grayware from remote sites.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 124,144 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 05 Oct 2012
Payload: Drops files

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • TROJ_ALYAK.AD

It may be downloaded from the following remote site(s):

  • http://www.{BLOCKED}nomy.com/xml/20110517/t2.gif

Installation

This Trojan drops and executes the following files:

  • %User Temp%\heshang.exe - also detected by Trend Micro as TROJ_SPYDROP.AD

(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.)

Autostart Technique

This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
AppInit_DLLs = "ws32help.dll"

(Note: The default value data of the said registry entry is {blank}.)

Other Details

This Trojan deletes itself after execution.

NOTES:
It renames the legitimate file %System%\ws2help.dll to %System%\ws2helpXP.dll and drops a malicious %System%\ws2help.dll which is detected by Trend Micro as TSPY_ONLINEG.SM3.

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 9.445.00
VSAPI OPR PATTERN Date: 07 Oct 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_SPYDROP.AD

    • TROJ_ALYAK.AD
    • TSPY_ONLINEG.SM3

Step 3

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\Microsoft\Windows NT\CurrentVersion\Windows
    • From: AppInit_DLLs = "ws32help.dll"
      To: AppInit_DLLs = ""

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_SPYDROP.AD. 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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