Analysis by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan searches for the file base.dcl in the AutoCAD search path to locate AutoCAD's current working folder. Once the current working folder is located, it searches for the file acad.lsp.

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.

  TECHNICAL DETAILS

File Size: 195,322 bytes
File Type: LSP
Initial Samples Received Date: 24 May 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.

NOTES:

It searches for the file base.dcl in the AutoCAD search path to locate AutoCAD's current working folder. Once the current working folder is located, it searches for the file acad.lsp.

It then reads the file acad.lsp to check the string "acadiso".

If the string is not found, it adds the line "load acadiso" to acad.lsp.

It then overwrites the contents of the file acadiso.lsp with the contents of the modified acad.lsp.

Once a new drawing file is opened, acad.lsp is automatically loaded and executed.

It checks if the name of the drawing file is Drawing.dwg.

If not, it overwrites the contents of the file acad.lsp with the contents of acadiso.lsp.

This malware creates dummy commands in place of the following commands to make them unavailable for user use:

  • ATTEDIT
  • XREF
  • XBIND

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.138.01
FIRST VSAPI PATTERN DATE: 25 May 2012
VSAPI OPR PATTERN File: 9.139.00
VSAPI OPR PATTERN Date: 25 May 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

Scan your computer with your Trend Micro product to delete files detected as ALS_BURSTED.CI. 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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