Hotmail users exposed to cookie snaffling exploit

Peril

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A cookie manipulation exploit that created a possible means for hackers to break into Hotmail accounts forced Microsoft into pulling a portion of its website last weekend.

The exploitable page - http://ilovemessenger.msn.com - has been updated to remove a cross site scripting flaw that was the subject of the exploit. But Alex de Vries, the Dutch security enthusiast who discovered the trick, warns that other portions of MSN's site are still vulnerable.

The exploit works in three stages. Hackers use security loopholes to inject hostile code onto MSN's web site. Hackers can then harvest Hotmail cookies from surfers redirected to this contaminated page by taking advantage of the use of Hotmail cookies across the MSN.com domain. Once hackers have a victim's cookie they can use tools to trick Hotmail into thinking they already logged on as this user.

The security flap comes days after Microsoft confessed its South Korean MSN Web site was the target of a hacking attack. Hackers succeeded in loading malicious code onto the site at part of an attack designed to steal passwords for Lineage, an on-line game popular in east Asia.

Microsoft declined our repeated requests to comment on the security of MSN Hotmail in light of de Vries's research. ®

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