Worm:W32/Mabezat

Classification

Category :

Malware

Type :

Worm

Aliases :

Worm:W32/Mabezat, Worm.Win32.Mabezat.b, Win32.Worm.Mabezat.Gen, Mabezat.B, W32.Mabezat.B! (Symantec), W32/Mabezat (McAfee), Virus:Win32/Mabezat.B (Microsoft), PE_MABEZAT.B-O (Trend Micro), W32/Mabezat-B (Sophos)

Summary

Worm:W32/Mabezat is a family of worms that spreads through infected email attachments, removable drives and network shares. The worm is also capable of functioning as a polymorphic file infecting virus, as it is able to infect executable files.

Removal

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.

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 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.

Technical Details

The technical details below refer to the Worm:W32/Mabezat.B variant, which is the most prevalent variant in the wild.

Installation

On execution, the worm drops the following files into the system root drives:

  • %root%\autorun.inf
  • %root%\zPharaoh.exe

The autorun.inf file contains the following code:

  • [AutoRun] ShellExecute=zPharaoh.exe shell\open\command=zPharaoh.exe shell\explore\command=zPharaoh.exe open=zPharaoh.exe

The above process is used to automatically execute zPharaoh.exe, which contains the worm's executable code. It also makes the malware capable of propagating via removable drives.

The virus also creates the following folder:

  • C:\Documents and Settings\%currently logged-in user%\Application Data\tazebama

And may drop the file zPharaoh.dat into it.

Infection

Mazebat.B infects files in a polymorphic manner by appending data to a section of clean file code, then relocating the entire section together with the appended data. This action means that the altered code differs in every infected file.

The virus also adds garbage code to the file to 'pad' it and increase its polymorphism.

Registry

The worm modifies the Registry to disable certain functions.

It deletes this registry entry so that Autoplay is turned off:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer NoDriveTypeAutoRun = 00000091

It also creates this entry:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced ShowSuperHidden = 00000000