Re: Repo with test cases for covert content attacks
Am 12.08.19 um 17:47 schrieb Stefan Claas via Gnupg-users: > Sebastian Schinzel wrote: > >> Dear all, >> >> Jens Müller just gave a talk at DEFCON about Covert Content Attacks >> against S/MIME and OpenPGP encryption and digital signatures in the >> email context. He just published the PoC emails that he used in the talk >> and they might be useful for further testing. >> >> https://github.com/RUB-NDS/Covert-Content-Attacks >> >> This is the paper describing the attacks from April 2019: >> >> https://arxiv.org/abs/1904.07550 > > Thanks for the info. I do no longer use a GPG plug-in MUA > combination, but are these 'Johnny you are fired' issues > already been resolved? I must admit I am a bit out of the > loop. Those are two different papers. 1. The 'Jonny, you are fired' paper solely dealt with signature spoofing and the repo is here: https://github.com/RUB-NDS/Johnny-You-Are-Fired 2. The paper mentioned in the thread above is 'Re: What's Up Johnny? -- Covert Content Attacks on Email End-to-End Encryption' and it contains some leftover attack cases that didn't make it into the Efail paper. It aims at exfiltrating the plaintext of encrypted mails, but with some degree of user interaction, e.g. replying to a malicious email. Lots of test cases and I am not aware of any current list of what MUA fixed which issue (correctly or incorrectly). Best, Sebastian ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Repo with test cases for covert content attacks
Dear all, Jens Müller just gave a talk at DEFCON about Covert Content Attacks against S/MIME and OpenPGP encryption and digital signatures in the email context. He just published the PoC emails that he used in the talk and they might be useful for further testing. https://github.com/RUB-NDS/Covert-Content-Attacks This is the paper describing the attacks from April 2019: https://arxiv.org/abs/1904.07550 Best, Sebastian ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
Backchannels via OCSP and CRL in S/MIME (Was: efail is imho only a html rendering bug)
Am 06.06.2018 um 20:19 schrieb Werner Koch: > Thanks for responding. However, my question was related to the claims > in the paper about using CRL and OCSP as back channels. This created the > impression that, for example, the certificates included in an encrypted > CMS object could be modified in a way that, say, the DP could be change > in the same was a a HTML img tag or to confuse the MIME parser. Table 5 shows that CRL and OCSP work as a backchannel in some clients, see I_1, I_2, I_3 in the PKI column. It is unclear if they can be used to exfiltrate plaintext in reality because changing them should break the signature. The caIssuer field (intermediate certificates) seems more appropriate for plaintext exfiltration. See the discussion in section 6.2. Note that we didn't analyze X.509v3 extensions for further backchannels. Again, whether CRL/OCSP/caIssuer can or cannot be used for plaintext exfiltration doesn't affect the overall security of S/MIME much. The central flaw remains malleable encryption. Best, Sebastian ___ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users
