TROJ_ZLOB.BIA

October 09, 2012
 Modified by: Sabrina Lei Sioting
 ALIASES:

Generic.dx!bdjb (McAfee); Gen:Win32.ExplorerHijack.bmW@aKOFNje (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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:

21,504 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Mar 2012

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 drops the following copies of itself into the affected system:

  • %Application Data%\wualct32.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MS32UPDATE = "%Application Data%\wualct32.exe"

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\1.tmp
  • %Application Data%\wualct32.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.. %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://sexy.{BLOCKED}ver.biz0000/a40437.asp
  • http://sexy.{BLOCKED}ver.biz0000/a60578.asp
  • http://sexy.{BLOCKED}ver.biz0000/a76625.asp
  • http://sexy.{BLOCKED}ver.biz0000/a93703.asp
  • http://sexy.{BLOCKED}ver.biz0000/a109734.asp
  • http://sexy.{BLOCKED}ver.biz0000/a125765.asp
  • http://sexy.{BLOCKED}ver.biz0000/a142843.asp
  • http://sexy.{BLOCKED}ver.biz0000/a158875.asp

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.818.03

FIRST VSAPI PATTERN DATE:

05 Mar 2012

VSAPI OPR PATTERN File:

8.819.00

VSAPI OPR PATTERN Date:

06 Mar 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

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • MS32UPDATE = "%Application Data%\wualct32.exe"

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ZLOB.BIA. 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 5

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\1.tmp
  • %Application Data%\wualct32.exe


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