Security experts say that the new Windows vulnerability revealed Monday by Microsoft Corp. has been used by crackers to attack at least one machine belonging to the U.S. Army. And, it turns out, the flaw used to attack the Web server was discovered not by Microsoft or an independent researcher, but by the attacker himself.
Experts at TruSecure Corp., based in Herndon, Va., received word of the attack on the Armys Web server last week through contacts within the Army. A Web server was attacked using a URL that was 4KB in length, and the machine was subsequently compromised. The server then immediately began mapping the network around it, looking for other vulnerable machines and seeing what else of interest was within reach. It then started sending the results of its mapping to a remote machine through TCP port 3389 using terminal services, said Russ Cooper, surgeon general at TruSecure.
Once the Army security staff realized the server had been compromised, it took the machine off-line and rebuilt it. But as soon as it was re-connected to the Internet, the server was compromised again. At that point, the Army personnel realized they were dealing with something new and went to Microsofts support site and filled out a Web form describing the issue. By the end of last week, Microsoft officials had produced a patch for the issue, which turned out to be a vulnerability in a Windows 2000 component used by IIS.
Microsoft on Monday released a patch for a critical vulnerability in a Windows 2000 component used by the WebDAV protocol. The vulnerability gives an attacker control of a vulnerable machine, officials said.
The vulnerability and its exploitation caught security officials at Microsoft and at independent bodies such as the CERT Coordination Center off guard. Attacks such as this that occur against previously unknown vulnerabilities are known as zero-day exploits, as there is no elapsed time between the discovery of the flaw and its exploitation. Although security experts say they have not seen any other attacks using this exploit, Cooper says he expects to see a worm based on it within a week or so.
"Its absolutely vital that people get rid of WebDAV on their boxes if they dont need it," Cooper said. "If they dont know whether theyre using it, chances are that theyre not and they should disable it."
And, because there is just one machine known to have been compromised with this attack so far, Cooper said he believes it was the work of an individual cracker and not a nation or other organization. "With the element of surprise like that, Id think a nation state would go after a large number of machines and not just this one," he said.
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