Software Engineering Institute

AOL Instant Messenger is a program for communicating with other users over the Internet and is widely used. During a buddy list transfer, a buffer overflow may occur. It has not been determined if this transfer happens via peer-to-peer, peer-to-server-to-peer, or both types of connections.

A denial-of-service situation is caused. It has not been determined if this vulnerability can lead to the remote execution of code.

Users can mitigate this vulnerability by upgrading AIM to version 4.8.2790 or higher. It is also reported that on March 14, 2002 AOL implemented server-side filtering to mitigate this vulnerability.

Block AIM Authentication at the Firewall

Blocking connections to login.oscar.aol.com on port 5190/tcp may prevent users on the local network from authenticating to the AIM server. This may be sufficient to prevent the vulnerability from being exploited.

Block Untrusted Messages

AIM permits the user to only accept messages from known peers. By enabling this feature, you may be able to prevent the vulnerability from being exploited. Note that you may still be vulnerable to attacks that originate from known peers if the vulnerability is exploited in a worm-like fashion.