Threat description




Sharpei is the first prepending file infector that targets Microsoft .NET architecture. The virus is composed from three different parts written in three different programming languages.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

Contact Support

F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Assembly component

The binary part is a simple dropper that drops the other two and checks for the presence of the .NET environment on the machine. When started it first copies itself to 'C:\MS02-010.exe' then drops the Visual Basic Script mass mailer part to a file called 'Sharp.vbs'. The .NET component is dropped to the Windows directory as 'cs.exe'. If the .NET environment is available the dropper starts the .NET component then exits.

.NET component

When it's started this component first drops a small Visual Basic Script file to the user's startup directory. The script displays the following message at the next login:

The virus infects all EXE files in the system directory and three other directories selected from 'Program Files'. The virus code is prepended to the host file. When the infected file is started it first tries to infect other files then it writes the host program to a temporary file ('temp.exe') and starts it.

Note: Even though .NET is supposed to be platform independent this virus will not work on non-intel PCs since it relies on the Intel binary part.

Visual Basic Script component

The Visual Basic Script component is a simple mass-mailer. It uses MS Outlook application to send messages to each recipient listed in each Outlook address book. The sent messages look as follows:

Subject: "Important: Windows update"
Body: "Hey, at work we are applying this update because it makes

 Windows over 50% faster and more secure. I thought I

 should forward it as you may like it."
Attachment: MS02-010.exe

By using as an attachment the name MS02-010 the worm tries to disguise itself as the patch described on Microsoft site:

https:// / TechNet / security / bulletin / MS02-010.asp

After mass-mailing itself, the script mass-mailing component deletes the sent emails and its copy Sharp.VBS from the infected system.


The Visual Basic Script component of this variant is the same as Sharpei.A

Submit a Sample

Suspect a file or URL was wrongly detected? Send it to our Labs for further analysis

Submit a Sample

Give And Get Advice

Give advice. Get advice. Share the knowledge on our free discussion forum.

More Info