Security flaw in Symantec's antivirus updater

The tool used to update the virus definitions in Symantec Corp.'s antivirus products has a security hole that can allow hostile code to be downloaded to PCs, according to the German hacking group Phenoelit.

LiveUpdate, the software used by Symantec's antivirus software to automatically update virus protections when updates become available, has flaws in both the 1.4 and 1.6 versions that allow for the attacks, Phenoelit said. When LiveUpdate 1.4 looks for updates, it attempts to connect to a specific server at Symantec, the group said. That connection, however, can be hijacked using a number of DNS (domain name server) attacks and rerouted to the server of the attacker's choice, Phenoelit said. If an attacker recreates the proper directory structure on the server the connection is sent to, any code can be downloaded to the user's machine and executed, the group said.

Version 1.6 doesn't have as extensive a vulnerability, but can fall victim to a network performance degradation attack, the group said. The use of a special Symantec data format for the updates and cryptographically signed update files prevents the same kind of attacks that LiveUpdate 1.4 can be hit with, Phenoelit said. Version 1.6 can also be prevented from receiving any updates, even if they are available, by using the connection hijacking attack and manipulating some files on the destination server, the group said.

Phenoelit notified Symantec of the flaw on Sept. 22, according to documents on the group's Web site. Symantec did not immediately return calls seeking comment.

The group advised users to upgrade to LiveUpdate 1.6, though it noted that LiveUpdate 1.6 is still vulnerable to the network degradation attack. It also urged Symantec to use new cryptographic signing methods and to tell its customer about the security flaws in LiveUpdate 1.4.