Bug#703587: libnss3 update disables some (self signed) certs (with Icedove)

[Erik C.J. Laan]

On 03/21/13 15:28, Daniel Kahn Gillmor wrote:
> On 03/21/2013 01:43 AM, Erik C.J. Laan wrote:
>> I upgraded libnss* from 2:3.13.6-2 (previously in wheezy) to 2:3.14.3-1 (new in wheezy).
>> Suddenly Icedove cannot connect to my IMAP-mail server anymore. That mail-server has
>> a self-signed certificate.
>> Thunderbird on other PCs (Win7) does not have the problem.
>> Mail-clients on other devices do nave the problem.
>> So it seems related to wheezy specifically.
>>     * What exactly did you do (or not do) that was effective (or
>>       ineffective)?
>> Restart Icedove.
>>     * What was the outcome of this action?
>>     * What outcome did you expect instead?
>> Downgraded libnss* to 2:3.13.6-2 to verify that libnss is the culprit. This solves the issue.
>> Upgrading to 2:3.14.3-1 again makes the issue appear again.
>> I also read some bug-reports. One of them talked about cert8.db being the problem.
>> So I moved ~/.icedove/<profile>/cert8.db to cert8.db.bak and stopped/started Icedove to
>> re-created cert8.db. This does not solve the issue, so the issue is not related to cert8.db and
>> thus not to #670882 and/or Mozilla bug 634074 .
>>
>> If you need any more information please specify.
>>
>>   have added a dump of the certificate generated with
>> 	openssl s_client -connect imap.intranet:993 -showcerts
>> for you and attached it to this report.
>>
>> To resolve this issue I have to downgrade to 2:3.13.6-2 and am thus stuck with a vulnerable
>> version. If using a different (non self-signed) certificate solves the issue, please specify.
>> The imap.intranet server certificate is going to expire in a few months anyway. I can generate
>> a certificate using a local PKI I've setup for OpenVPN after generating this certiticate in 2005.
> The self-signed certificate in question uses RSA-MD5 as a signature.
> MD5 is deprecated in general, so I suspect this is the problem.  You
> could probably even re-generate the same self-signed certificate with
> the same key using SHA1 as the message-signing digest and it would work.
>
> However, this sounds to me like a bug in the logic of the upgraded
> version of NSS.  If a certificate is already explicitly known locally
> and is marked as valid for the remote peer in cert8.db, then NSS should
> be fine using it regardless of the digest algorithm used in the
> certificate signature.
>
> Regards,
>
> 	--dkg
>
Thanks for the suggestion. I will generate a new certificate and avoid md5.

I will report back today or tomorrow whether that solved the issue.

-- Met vriendelijke groeten/With kind regards, Erik Laan.