Sophos

W32/Sasser-A

Aliases
  • W32/Sasser.worm
  • Win32/Sasser.A
  • W32.Sasser.Worm
  • WORM_SASSER.A
Category
Type
What to do
Prevalence low high

Summary

 
Protection available since 1 May 2004 06:48:08 (GMT)
Last updated 12 May 2004 09:34:45 (GMT)
Detected by All Sophos products
  • Free virus, spyware, and adware scan
  • Test your existing anti-virus protection
  • Find threats your anti-virus missed

Action

More Information

W32/Sasser-A worm is a self-executing network worm, which travels from infected machines via the internet, exploiting a Microsoft Windows vulnerability MS04-011, and instructs vulnerable systems to download and execute the viral code.

It does not spread via email.

Infected computers may run more slowly than normal and shut down intermittently.

W32/Sasser-A attempts to connect to computers through ports TCP/9996 and TCP/445. If the Windows computers are not patched against the LSASS vulnerability, an FTP script is downloaded and executed, which connects to port 5554 and downloads a copy of the worm via FTP (File Transfer Protocol).

The worm copies itself to the Windows folder with the filename avserve.exe and sets the following registry key to auto-start on user logon:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run\avserve = avserve.exe

The Microsoft vulnerability was first reported on 13 April, and Microsoft have issued protection, which can be downloaded from Microsoft Security Bulletin MS04-011.

Further reading: Information on the Sasser internet worm

RSS|Atom
Get reports about the latest virus and spyware threats delivered to your computer