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TITLE:
Yahoo! Messenger Denial of Service Weakness

SECUNIA ADVISORY ID:
SA20773

VERIFY ADVISORY:
http://secunia.com/advisories/20773/

CRITICAL:
Not critical

IMPACT:
DoS

WHERE:
>From remote

SOFTWARE:
Yahoo! Messenger 7.x
http://secunia.com/product/5956/

DESCRIPTION:
Ivan Ivan has discovered a weakness in Yahoo! Messenger, which
potentially can be exploited by malicious people to cause a DoS
(Denial of Service).

The weakness is caused due to an error within the handling of certain
messages. This can be exploited to crash another user's Yahoo!
Messenger client via a specially crafted message that contains a
non-ascii character.

For example:
s:[space]msg[alt+0160]:---------------------------------------------iframe
onload=$InlineAction()>:)

Successful exploitation requires that the user has not configured the
application to ignore malicious users that are not on his Messenger
list.

The weakness has been confirmed in version 7.5.0.814. Other versions
may also be affected.

SOLUTION:
Configure Yahoo! Messenger to ignore users that are not in the
Messenger list.

PROVIDED AND/OR DISCOVERED BY:
Ivan Ivan

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About:
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