Analysis by: Jaime Benigno Reyes
ALIASES:

Worm:ALisp/Kenilfe.gen!A (Microsoft), ALS/Bursted (McAfee), ALS.Bursted.A (Symantec)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size: 8,545 bytes
File Type: Other
Memory Resident: No
Initial Samples Received Date: 17 Jul 2010

Arrival Details

This worm 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 worm drops the following copies of itself into the affected system:

  • %Current%\acad.fas
  • %Windows%\DivX.fin
  • %System%\SHFR.CMD
  • {AutoCAD installation directory}\acad.fas
  • {AutoCAD installation directory}\Fonts\isohztxt.shx

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

Other System Modifications

This worm adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\FileKen

HKEY_CURRENT_USER\Software\FileKen\
settings

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Setup\
BEI_ZHU

It also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows Script Host\Settings
Enabled = "1"

Other Details

This worm connects to the following possibly malicious URL:

  • http://www.{BLOCKED}s.com/z/bkd/gif
  • http://{BLOCKED}bd.8800.org

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 7.316.08
FIRST VSAPI PATTERN DATE: 17 Jul 2010
VSAPI OPR PATTERN File: 7.317.00
VSAPI OPR PATTERN Date: 18 Jul 2010

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Delete this registry key

[ 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\FileKen
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Setup\BEI_ZHU

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 Script Host\Settings
    • Enabled = "1"

Step 4

Scan your computer with your Trend Micro product to delete files detected as ALS_CHENGWA.B. 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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