1. Symantec/
  2. Security Response/
  3. W32.Blaster.F.Worm


Risk Level 2: Low

September 1, 2003
February 13, 2007 12:06:38 PM
Also Known As:
W32/Lovsan.worm.f [McAfee], W32/Blaster-F [Sophos], WORM_MSBLAST.G [Trend], Win32.Poza.F [CA]
Systems Affected:
CVE References:

W32.Blaster.F.Worm is a worm that exploits the DCOM RPC vulnerability (described in Microsoft Security Bulletin MS03-026) using TCP port 135. The worm targets only Windows 2000 and Windows XP computers. While Windows NT and Windows 2003 Servers are vulnerable to this exploit (if not properly patched), the worm is not coded to replicate to those systems. This worm attempts to download the Enbiei.exe file into the %Windir%\System32 folder, and then execute it.

W32.Blaster.F.Worm does not have a mass-mailing functionality.

Additional information is available in the Microsoft article, "What You Should Know About the Blaster Worm and Its Variants."

We recommend that you block access to TCP port 4444 at the firewall level, and then block the following ports, if you do not use the following applications:
  • TCP Port 135, "DCOM RPC"
  • UDP Port 69, "TFTP"

The worm also attempts to perform a Denial of Service (DoS) on tuiasi.ro. At the time of writing this description, tuiasi.ro resolves to a blank address.

Click here for more information on the vulnerability that this worm exploits, and to find out which Symantec products can help mitigate risks from this vulnerability.

NOTE: Beta Definition build #24246 or later will detect this variant.

Antivirus Protection Dates

  • Initial Rapid Release version September 2, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version September 2, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date September 3, 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.
Writeup By: Douglas Knowles

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