W32.Sasser.D

The W32.Sasser.D worm:

• Is a variant of W32.Sasser.Worm.
• Attempts to exploit the LSASS vulnerability described in Microsoft Security Bulletin MS04-011.
• Spreads by scanning randomly selected IP addresses for vulnerable systems.

W32.Sasser.D differs from W32.Sasser.Worm as follows:

• Uses a different mutex: SkynetSasserVersionWithPingFast.
• Uses a different file name: skynetave.exe.
• Has a different file size: 16,384 bytes.
• Has a different MD5.
• Creates a different value in the registry: "skynetave.exe."
• Uses a different port for the remote shell: 9995/tcp.
• Will exit before running any code with an error on some Windows 2000 systems.
• Has an updated routine for finding vulnerable computers. W32.Sasser.D sends an ICMP echo request before attempting to make a connection. This change may prevent the worm from properly executing on Windows 2000 systems.

W32.Sasser.D can only execute on Windows XP systems. The worm can exploit a vulnerable (unpatched) Windows 2000 machine remotely and copy itself to that machine. However, it will exit before running any code. In such cases, this worm will produce the following error:

The procedure entry point IcmpSendEcho could not be located in the dynamic link library iphlpapi.dll.

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Notes:

• The MD5 hash value of this worm is 0X03F912899B3D90F9915D72FC9ABB91BE.
• Block TCP ports 5554, 9995, and 445 at the perimeter firewall and install the appropriate Microsoft patch (MS04-011) to prevent the remote exploitation of the vulnerability.
• This threat is written in C++ and is packed with PECompact.

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Protection

• Initial Rapid Release version May 3, 2004
• Latest Rapid Release version March 3, 2008 revision 035
• Initial Daily Certified version May 3, 2004
• Latest Daily Certified version March 3, 2008 revision 037
• Initial Weekly Certified release date May 3, 2004

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 50 - 999
• Number of Sites: More than 10
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Medium

Distribution

• Distribution Level: High