Tag Archives: POODLE

Testing for POODLE_TLS Manually

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Testing for the original POODLE vulnerability was easy because it was an inherent problem with SSLv3, so if you find SSLv3 enabled then you’ve found POODLE (although other factors such as cipher suite preference have a role to play – see my previous post). Like Heartbleed, though, testing for POODLE over TLS is conceptually easy but it falls within a class of flaws that requires bespoke tools as an unpatched version of openssl, for example, won’t do what you want it to do. This article discusses how the Python tlslite library can be used to test for POODLE_TLS – and so much more. Continue reading →

Thoughts on Testing for POODLE

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I recently did an internal presentation on POODLE – what the flaw is and how to test for it – and a version of the slides can be found here. Obviously much has been written about the vulnerability, its mitigations and what the future holds. What follows expands on the testing aspect of the presentation, with a few pointers on manual checks if you feel you need to verify or clarify – and possibly even add to – what the tools are telling you. Continue reading →

Testing for Cipher Suite Preference

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It’s often important to know which SSL/TLS cipher suite is preferred by a server to alter the risk rating of a particular issue. For POODLE, if the server prefers RC4 ciphers over SSLv3 connections then it’s very unlikely that a connection will be vulnerable to POODLE. Similarly, if a server prefers block ciphers then reporting RC4 support should be appropriately adjusted. Occasionally tools conflict over which cipher suite is preferred so I thought I’d write up how to resolve this manaully in the spirit of the SSL/TLS manual cheatsheet. Continue reading →

POODLE and the TLS_FALLBACK_SCSV Remedy

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The POODLE attack announced very recently depends largely on a protocol downgrade attack (which I covered in my SSL/TLS presentation at BSides). I don’t think this aspect of TLS security was widely appreciated – but it is now! It’s a fair bet that any technical article about POODLE includes the phrase “TLS_FALLBACK_SCSV” as a remedy. This article discusses the mechanism proposed to protect us from attackers forcing TLS downgrades. NEW (16/10/14): while I was writing this I thought of a small but potential compatibility problem, which in fact could do us all a favour. I checked with the authors of the RFC and Adam Langley was kind enough to reply back so I’ve added added a new section below. Continue reading →