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EEYE: Yahoo! Mail Account Filter Overflow Hijack
From: Drew Copley (dcopleyEEYE.COM)
Date: Wed Apr 21 2004 - 13:11:46 CDT
"Yahoo! Mail" Account Filter Overflow Hijack
April 19, 2004
March 10, 2004
"Yahoo! Mail" is one of the Internet's most popular
web based email solutions. They provide free email and
large capacity storage, as well as subscription-based
services such as mail forwarding, expanded storage and
personalized email addresses.
eEye Digital Security has discovered a security hole in
"Yahoo! Mail" which allows a remote attacker to take over
an account remotely by sending a specially crafted email.
[->a bunch of chars here [spaces are most stealth], the whole
file size will be just about 100KB]
[this causes the filter to not work... the code is then run
The pseudo-diagram above explains the scenario rather well.
For whatever reason, Yahoo's email filter simply does not
work on files which exceed a certain range. This kind of
software issue is relatively common.
A remarkable note about this bug is that no one seems to
have found it before.
As far as anyone knows.
Drew's Happy-Happy Quote for the Day:
Ben Franklin, "Three can keep a secret if two are dead."
Yahoo! Mail is a hosted, web based service, hence users
do not need to patch. Yahoo has already fixed this bug,
therefore all Yahoo accounts are now completely safe from
Yahoo! has been notified and has rectified the issue.
Drew Copley, eEye Digital Security (dcopley eeye.com), Research Engineer
thanks to "http-equiv" for additional research
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To all of you out there that don't use turn signals.
Sooner or later your time is going to come. And a special
greeting to all of these competitors of ours making some extra
cash by selling pre-fix vulnerabilities through pay for play
"mailing lists". I am sure North Korea, the Yakuza, the
"Triads", the Russian Mafiya, La Costa Nostra, and every
other criminal state or organization appreciates your type of
"Partial Full Disclosure for a Darn Good Price" motto.
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