From: fenris at HammerofGod.com (Fenris The Wolf)
Subject: Anyone buy this?

http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/
news/IARWSV.asp

Information about Reported Web Security Vulnerability

There has been a good deal of discussion and speculation recently about a
reported security vulnerability involving how Internet Explorer identifies
secure web sites. The Microsoft Security Response Center has investigated
the report and we'd like to provide information about the issue and our
plans for addressing it.

The report discusses a problem in the way Internet Explorer establishes
secure web sessions via the Secure Socket Layer (SSL) protocol. SSL provides
a number of security features, but of particular interest in this case is
its ability to verify that a web site is indeed the site it purports to be.
A flaw in the SSL implementation could enable an attacker to create a web
site that bypasses this protection, and masquerades as a different web
site - one that the user might trust and provide with personal information
such as credit card numbers.

The flaw could enable an attacker who has been issued a valid SSL digital
certificate to create a seemingly valid additional certificate that purports
to belong to a different web site. When a user visited the site, the
attacker could present the second certificate in an attempt to convince the
user that he or she was actually at the site it claimed.

While Microsoft has confirmed that the flaw does exist, it's important to
note that actually exploiting it would be difficult, for several reasons:

The attack scenario is narrow. If a user arrived at the attacker's web site
in the belief that it was actually a different, legitimate site, the flaw
could allow the attacker to bolster this belief. But it provides no way to
make the user actually arrive at the attacker's site, let alone in the
belief that it is a different site. Doing this would likely require that the
attacker be able to modify the Internet infrastructure that the user
transited, via a technique such as DNS cache poisoning. However, such
techniques are difficult, temporary, and generally require favorable network
topology.

The identity of the attacker could easily be determined. To exploit the
vulnerability, the attacker would require a valid SSL digital certificate,
issued by a trusted Certificate Authority. However, most commercial
Certificate Authorities require substantial proof of identity before issuing
such a certificate, thereby making it possible for law enforcement
authorities to determine who the attacker was. (Information on verifying
certificates can be found here).

The user would always have the ability to determine the truth. Anytime an
SSL session has been established, an icon shaped like a lock is present in
the lower right corner of the screen. By double-clicking on the icon, the
user can see information about the site's digital certificate, including the
identity of the issuer. This would clearly show that, in contrast to the
norm, this one hadn't been directly issued by a commercial Certificate
Authority.

Despite the many challenges associated with exploiting the flaw, there is
indeed a flaw here and Microsoft is developing a patch that will eliminate
it. When the patch is available, we will release a security bulletin
discussing the overall issue and how to apply the patch.

We regret any anxiety that customers may have experienced regarding this
issue. Clearly, it would have been best if a balanced assessment of the
issue and its risk had been available from the start. However, the report,
which neglected to discuss any of the challenges associated with actually
exploiting the vulnerability, was made public without any advance warning to
Microsoft. Responsible security researchers have the safety of users in mind
and work with vendors to ensure that the information published about
potential vulnerabilities is balanced and, above all, correct. Had this been
done in this case, all users' interests would have been better served.

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