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Re: [saag] NSA bug in Windows 10

Daniel Van Geest <Daniel.VanGeest@isara.com> Fri, 17 January 2020 13:36 UTC

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From: Daniel Van Geest <Daniel.VanGeest@isara.com>
To: Peter Gutmann <pgut001@cs.auckland.ac.nz>, Benjamin Kaduk <kaduk@mit.edu>, Dan Brown <danibrown@blackberry.com>
CC: IETF SAAG <saag@ietf.org>
Thread-Topic: [External]Re: [saag] NSA bug in Windows 10
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Date: Fri, 17 Jan 2020 13:37:06 +0000
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Subject: Re: [saag] NSA bug in Windows 10
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The best summary I’ve seen is here:
https://blog.trailofbits.com/2020/01/16/exploiting-the-windows-cryptoapi-vulnerability/

In short, a received root was being compared to the trusted root based only on
the public key, but the private key and parameters of the received root was
generated from the trusted public key using Vaudenay.  Then verification was
done using the received root since it was “the same” as the trusted root.

Daniel Van Geest


On 2020-01-17, 6:55 AM, "saag on behalf of Peter Gutmann" <saag-bounces@ietf.org<mailto:saag-bounces@ietf.org> on behalf of pgut001@cs.auckland.ac.nz<mailto:pgut001@cs.auckland.ac.nz>> wrote:

Benjamin Kaduk <kaduk@mit.edu<mailto:kaduk@mit.edu>> writes:

I remember reading something that involved [...]

Based on, admittedly, zero reading of stuff around this so far (trying to find
some time this weekend), I assume it's of the type covered here:

Digital Signature Schemes with Domain Parameters
https://lasec.epfl.ch/pub/lasec/doc/Vau04b.pdf

Or at least that's one possible vuln that you get from not checking domain
parameters.

Peter.

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