SQL Slammer

In January of 2003,  the SQL Slammer worm caused a DDoS in some Internet hosts and dramatically slowed down general Internet traffic. It spread rapidly, infecting most of its 75,000 victims within ten minutes. Slammer was first brought to the attention of the public by Michael Bacarella. Although titled “SQL slammer worm”, the program did not use the SQL language; it exploited a buffer overflow bug in Microsoft’s flagship SQL Server and Desktop Engine database products, for which a patch had been released six months earlier in MS02-039. Other names include W32.SQLExp.Worm, DDOS.SQLP1434.A, the Sapphire Worm, SQL_HEL, W32/SQLSlammer and Helkern.

The worm was based on proof of concept code demonstrated at the Black Hat Briefings by David Litchfield, who had initially discovered the buffer overflow vulnerability that the worm exploited. It is a small piece of code that does little other than generate random IP addresses and send itself out to those addresses. If a selected address happens to belong to a host that is running an unpatched copy of Microsoft SQL Server Resolution Service, the host immediately becomes infected and begins spraying the Internet with more copies of the worm program.