Worm:ACAD/Kenilfe.A

Classification

Malware

Worm

ACAD

Kenife, Kenilfe, Kenilfe.A, Worm.Acad.Kenilfe.A, AutoCAD.Kenilfe, AL/Kenilfe

Summary

Kenilfe is a malicious AutoCAD program that propagates via removable drives. It also attempts to download Visual Basic Scripts from remote servers, if certain conditions are met.

Removal

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

Suspect a file is incorrectly detected (a False Positive)?

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note You need administrative rights to change the settings.

Find out more

Knowledge Base

Find the latest advice in our Community Knowledge Base.

User Guide

See the user guide for your product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details

Installation

During installation, the malware creates the following registry entries:

  • HKEY_CURRENT_USER\Software\KenFiles\settings TMN = %Random Name% or "Temp" TMNL = %Random Name% or "TMNL" SHXN = %Random Name% or "isoshfr" CXBB = 102 GXBZ = 103 pth0 = %IP Address of updatebd.8800.org% (or "221223921023103" if cannot ping the host) pth3 = %Current Date% pth4 = %Current Date% pth5 = %Current Date% basepth = %User Support Folder% fontpth = %AutoCAD Fonts Folder%

It then creates copies of itself in the following locations:

  • %Folder of Current Drawing%\acad.fas
  • %User Support Folder%\acad.fas
  • %AutoCAD Fonts Folder%\%SHXN%.shx

Where%SHXN% is the same as the SHXN value found in the registry entry (above).

It also creates the following files:

  • %Windows Folder%\DivX.fin - possibly some sort of a infection marker
  • %Windows Folder%\system32\%TMN%.cmd - contains commands that will create copies of the malware (same as those mentioned earlier)

Where%TMN% is also the same as the TMN value found in the registry entry.

It enables the Windows Scripting Host by creating the following registry entry:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Script Host\Settings Enabled = 1

Then deletes the registry key:

  • "HKEY_CURRENT_USER\Software\FileKen\settings"

It also deletes the following files:

  • isohztxt.shx
  • acad.fas1
  • logo.gif
  • isomianyi.shx

Payload

Once installed, Kenilfe downloads and executes Visual Basic Scripts based on the following conditons:

  • https://www.cadgs.com/[...]/gxcx.[...] - if the 3rd octect of the IP address of updatebd.8800.org > 102
  • https://www.cadgs.com/[...]/gxmz.[...] - if the 4th octect of the IP address of updatebd.8800.org > 103

Example: if the IP address of updatebd.8800.org is 221.239.103.104, both Visual Basic Scripts will be downloaded and executed.

These conditions are specified in the CXBB and GXBZ registry, respectively.

Propagation

The malware enumerates all folders in all removable drives. If it finds the file acad.fas, it replaces the file with a copy of

  • %AutoCAD Fonts Folder%\isomianyi.shx.

Alternatively, if the folder contains a drawing (.dwg) file, it will create the file acad.fas (which is really a copy of isomianyi.shx).

It then creates a file named pagefile in the same drive location, to mark that it is done infected the drive.

During the enumeration process, the malware also renames the following files to append a "_bak" in their filenames:

  • acad.lsp
  • acad.sys
  • acad.vlx
  • acadapp.lsp
  • acadappp.lsp
  • acadapq.lsp
  • acadiso.lsp
  • acadsmu.fas
  • dwgrun.bat
  • isohztxt.shx
  • lcm.fas
  • winfas.ini