9th Apr 2002 [SBWID-5248]
COMMAND
Internet Explorer abusive SSL certificate trusting
SYSTEMS AFFECTED
All current versions
PROBLEM
0x90 [http://www.invisiblenet.net] found following, regarding SSL issue
in Internet explorer :
The reason for the ssl issue in Microsoft\'s IE browser is because when
requestsing an
<img src=\"https://website.com/doesnotexist.gif\" width=1 height=1>
before going to the page, it has chosen to not question the cert at
that point either, because of the embedded object in the source code.
Even if the embedded object does not exist, it will still trust from
that point on. This is a small and stupid bug on IE\'s part, and is an
easy fix, the question of why it isn\'t is really a microsoft issue.
This can easily be exploitable by the Man in the Middle/replay attack
as Eve can request the img src in midstream upon Alice\'s request for
cert, then send a signed but not valid to the host\'s cert, allowing
Eve to handle the trusting before Alice is even notified.
A proof of concept for your browser checking is here
http://ssltest.invisiblenet.net
SOLUTION
until fixed, I advise everyone to check all certs if using IE, and even
if not, don\'t click yes on impulse. This is not a likely attack from
kiddiez or hackers, but the powers above us can easily exploit this, or
the nearest network administrator on your corporate network :)
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