W32/Donut

This page shows details and results of our analysis on the malware W32/Donut

Download Current DAT: 6614

Threat Detail

Malware Type: Virus

Malware Sub-type: File Infector

Discovery Date: 2002-01-09

Next Steps:

Overview
Characteristics
Symptoms
Method of Infection
Removal

Overview

This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.

Minimum DAT

4181 (2002-01-16)

Updated DAT

4241 (2003-01-08)

Minimum Engine

5.1.00

File Length

N/A

Description Added

2002-01-09

Description Modified

2002-02-04

Malware Proliferation

Characteristics

This is the first virus to make use of Microsoft's .NET architecture. Due to the uncommon system requirements and replicating environment, the virus is unlikely to become widespread. The .NET architecture must be installed on Windows2000/XP in order for the virus to function and it only infects some MSIL PE files.

W32/Donut is a file infector that infects certain other .NET executables using the .EXE extension. Files in the current directory and up to 20 directories above it are infected. Then the virus exits. It does not stay resident in memory. When run, there is a 10 percent chance that a dialog box will be displayed.

It is primarily written in Win32 assembly and some MSIL (Microsoft Intermediate Language)

Symptoms

Display of message box entitled, ".NET.dotNET by Benny/29A" which reads, "This cell has been infected by dotNET virus!".

Method of Infection

This is a file infecting virus which spreads to certain other .NET executables on the local system.

Removal

All Users:
Use current engine and DAT files for detection and removal.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

But in some particular cases, the following steps need to be taken.

Please go to the Microsoft Recovery Console and restore a clean MBR.

On Windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password.
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions.
Reset and remove the CD from CD-ROM drive.

On Windows Vista and 7:

Insert the Windows CD into the CD-ROM drive and restart the computer.
Click on "Repair Your Computer".
When the System Recovery Options dialog comes up, choose the Command Prompt.
Issue 'bootrec /fixmbr' command to restore the Master Boot Record.
Follow onscreen instructions.
Reset and remove the CD from CD-ROM drive.