A buffer overflow vulnerability in AOL Instant Messenger (AIM) could be exploited to gain complete control of a Windows machine, security research group w00w00 has revealed.

The flaw involves the way AIM processes the "Play Game with a Buddy" option. A string of text can cause a buffer overflow in the victim's client, which can then be exploited to take control of the victim's Windows machine.

All versions from the current beta back to version 4.3 are confirmed affected. Earlier versions have not been tested and may also be vulnerable.

w00w00.org member Matt Conover posted a harmless exploit demonstrating the ease with which the hole can be abused. The exploit merely shuts down a victim's AIM client remotely, but could easily be adapted to more destructive uses.

AOL says they'll have a patched version available in a matter of days. To protect yourself from exploitation in the mean time, Conover recommends installing Robbie Saunders' AIM Filter and restricting incoming messages to those on one's buddy list.

The Netscape inline AOL client is probably vulnerable if it supports games requests, and probably not vulnerable if it does not, Conover says.

Because w00w00 gave AOL only a week or so to patch the vulnerability before releasing it to several security mailing lists, the group has been criticized by company representatives and some members of the security research community, including TruSecure's Russ Cooper, who is quoted by the Associated Press characterizing the decision as "irresponsible."

Full disclosure is of course a controversial point in the security community; but wherever one comes down on the issue, it's undeniable that quick disclosure does result in quick patching. ®