Discovered: January 24, 2003
Updated: February 13, 2007 11:42:35 AM
Also Known As: SQL Slammer Worm [ISS], DDOS.SQLP1434.A [Trend], W32/SQLSlammer [McAfee], Slammer [F-Secure], Sapphire [eEye], W32/SQLSlam-A [Sophos]
Type: Worm
Systems Affected: Windows
CVE References: CAN-2002-0649

W32.SQLExp.Worm is a worm that targets the systems running Microsoft SQL Server 2000, as well as Microsoft Desktop Engine (MSDE) 2000. The worm sends 376 bytes to UDP port 1434, the SQL Server Resolution Service Port.

The worm has the unintended payload of performing a Denial of Service attack due to the large number of packets it sends.

Symantec Security Response strongly recommends that all the users of either Microsoft SQL Server 2000 or MSDE 2000 audit their computers for the vulnerabilities that are referred to in Microsoft Security Bulletin MS02-039 and Microsoft Security Bulletin MS02-061 .

Symantec Security Response also recommends that you:

  • Configure perimeter devices to block the ingress UDP traffic to port 1434 from untrusted hosts.
  • Block the egress UDP traffic from your network to the destination port 1434.

For more information on the SQL outbreak, refer to the Web cast at: .

Removal Tool
Symantec has provided a tool to remove the infections of W32.SQLexp.Worm. Click here to obtain the tool. Try this tool first, as it is the easiest way to remove this threat. Because the worm resides in memory only and is not written to disk, the virus definitions do not detect this threat. Symantec Security Response recommends that you follow the measures described in this document to deal with this threat.

Please refer to the Technical Details section below for information on how to configure the Symantec products to detect this threat.

Antivirus Protection Dates

  • Initial Rapid Release version January 25, 2003
  • Latest Rapid Release version November 04, 2019 revision 019
  • Initial Daily Certified version January 25, 2003
  • Latest Daily Certified version November 04, 2019 revision 065

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

Technical Description

When W32.SQLExp.Worm attacks a vulnerable system, it does the following:

  • Sends itself to the SQL Server Resolution Service, which listens on UDP port 1434.
  • Takes advantage of a buffer overflow vulnerability that allows a portion of system memory to be overwritten. When the worm does this, it runs in the same security context as the SQL Server service.
  • Calls the Windows API function, GetTickCount, and uses the result as a seed to randomly generate IP addresses.
  • Opens a socket on the infected computer and attempts to repeatedly send itself to UDP port 1434 on the IP addresses it has generated, by using an ephemeral source port. Because the worm does not selectively attack the hosts in the local subnet, large amounts of traffic are the result.
W32.SQLExp.Worm SQL Server Worm Analysis
Deepsight™ Threat Management System Threat Analysis

For more information about the vulnerability that this worm exploits, refer to the following article at: .

Symantec Gateway Security
Symantec has released updates for Symantec Gateway Security via LiveUpdate. Additionally, you may click here to learn about limiting the ingress traffic for W32.SQLExp.Worm using Symantec Gateway Security.

Enterprise Security Manager
Symantec has released an Enterprise Security Manager policy for this threat. Click here for more information.

Intruder Alert
Symantec has released an Intruder Alert 3.5/3.6 Integration Policy for NetProwler 3.5x. Click here for more information.

Symantec has released Security Update 22 for NetProwler 3.5.1, which includes a detection for W32.SQLExp.Worm. Click here for more information.

Symantec Enterprise Firewall, Symantec VelociRaptor, Symantec Raptor Firewall
Click here to learn about limiting the ingress traffic for W32.SQLExp.Worm using Symantec's Enterprise Firewall, VelociRaptor, and Raptor products.

Symantec ManHunt
Symantec ManHunt Protocol Anomaly Detection technology detects the traffic generated by this threat as a UDP flood. To specifically detect this threat as W32.SQLExp.Worm, Symantec recommends that users of the Symantec ManHunt product activate the HYBRID MODE function and apply the following custom rule:

*******************start file********************

#Variables need to be set dependent on the users network. Below are examples on how to set
# variable. For more information see Symantec ManHunt Administrative Guide: Appendix A.
var HOME_NET any
alert udp $EXTERNAL_NET any -> $HOME_NET 1434 (msg:"W32.SQLEXP.Worm propagation"; content:"|68 2E 64 6C 6C 68 65 6C 33 32 68 6B 65 72 6E|"; content:"|04|"; offset:0; depth:1;)


For more information on how to create custom signatures, refer to the "Symantec ManHunt Administrative Guide: Appendix A Custom Signatures for HYBRID Mode."


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.


Removal Tool
Symantec has provided a tool to remove the infections of W32.SQLexp.Worm. Click here to obtain the tool. Try this tool first, as it is the easiest way to remove this threat. Because the worm resides in memory only and is not written to disk, the virus definitions do not detect this threat. Customers are recommended to follow the measures described in this document to control with this threat.

Writeup By: Douglas Knowles