CVE-2009-2474: fix handling of NUL in SSL cert subject names

Arfrever Frehtes Taifersar Arahesis arfrever.fta at gmail.com
Wed Aug 19 13:52:14 EDT 2009


2009-08-18 17:51:03 Joe Orton napisał(a):
> At Black Hat USA '09, Dan Kaminsky and Moxie Marlinspike disclosed a way 
> to bypass cert verification in some SSL implementations by using a NUL 
> (zero) byte in either the common Name field of the subject attribute, or 
> in the "subject alternative name" attribute.
> 
> Certificate Authorities should be verifying and rejecting certificates 
> with a NUL byte embedded in either of these attributes, but, allegedly 
> some Internet CAs are, or have in the past, signed such certs.
> 
> All versions of neon versions up to 0.28.5 inclusive are vulnerable to 
> this issue, where neon is built with SSL support using OpenSSL.  An 
> attacker holding a bogus cert signed by a trusted CA could perform a 
> man-in-the-middle attack against a server.
> 
> This issue has been assigned CVE name CVE-2009-2474.
> 
> All versions of neon older than 0.28.6 are affected, where linked 
> against OpenSSL. 
> 
> If neon is linked against GnuTLS, version 2.8.2 or later must be used to 
> avoid the vulnerability.

Do you mean that Neon 0.28.6 with GnuTLS 2.8.1 is vulnerable or that
Neon 0.28.5 with GnuTLS 2.8.2 isn't vulnerable?

> No changes are necessary to existing releases 
> of neon to avoid the vulnerability if and only if used in conjuction 
> with GnuTLS version 2.8.2 or later.

-- 
Arfrever Frehtes Taifersar Arahesis
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