OpenID/Debian PRNG/DNS Cache poisoning advisory

Clausen, Martin (DK - Copenhagen) mclausen at deloitte.dk
Tue Aug 12 04:55:53 EDT 2008


You could use the SSL Blacklist plugin
(http://codefromthe70s.org/sslblacklist.asp) for Firefox or heise SSL
Guardian
(http://www.heise-online.co.uk/security/Heise-SSL-Guardian--/features/11
1039/) for IE to do this. If presented with a Debian key the show a
warning.

The blacklists are implemented using either a traditional blacklist
(text file) or distributed using DNS.

~~martin

-----Original Message-----
From: owner-cryptography at metzdowd.com
[mailto:owner-cryptography at metzdowd.com] On Behalf Of Eric Rescorla
Sent: 8. august 2008 17:06
To: Ben Laurie
Cc: bugtraq at securityfocus.com; security at openid.net; OpenID List;
cryptography at metzdowd.com; full-disclosure at lists.grok.org.uk
Subject: Re: OpenID/Debian PRNG/DNS Cache poisoning advisory

At Fri, 8 Aug 2008 11:50:59 +0100,
Ben Laurie wrote:
> However, since the CRLs will almost certainly not be checked, this 
> means the site will still be vulnerable to attack for the lifetime of 
> the certificate (and perhaps beyond, depending on user behaviour). 
> Note that shutting down the site DOES NOT prevent the attack.
> 
> Therefore mitigation falls to other parties.
> 
> 1. Browsers must check CRLs by default.

Isn't this a good argument for blacklisting the keys on the client side?

-Ekr

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