TY  - CHAP
A1  - Müller, Jens
A1  - Brinkmann, Marcus
A1  - Poddebniak, Damian
A1  - Böck, Hanno
A1  - Schinzel, Sebastian
A1  - Smomrosvsky, Juraj
A1  - Schwenk, Jörg
T1  - “Johnny, you are fired!” – Spoofing OpenPGP and S/MIME Signatures in Emails
T2  - 28th Usenix Security Symposium, Santa Clara, CA, USA
N2  - OpenPGP and S/MIME are the two major standards to en-crypt and digitally sign emails.  Digital signatures are sup-posed to guarantee authenticity and integrity of messages. Inthis work we show practical forgery attacks against variousimplementations of OpenPGP and S/MIME email signatureverification in five attack classes: (1) We analyze edge casesin S/MIME’s container format.  (2) We exploit in-band sig-naling in the GnuPG API, the most widely used OpenPGPimplementation.  (3) We apply MIME wrapping attacks thatabuse  the  email  clients’  handling  of  partially  signed  mes-sages.  (4) We analyze weaknesses in the binding of signedmessages to the sender identity.  (5) We systematically testemail clients for UI redressing attacks.Our attacks allow the spoofing of digital signatures for ar-bitrary  messages  in  14  out  of  20  tested  OpenPGP-capableemail  clients  and  15  out  of  22  email  clients  supportingS/MIME signatures.  While the attacks do not target the un-derlying cryptographic primitives of digital signatures, theyraise  concerns  about  the  actual  security  of  OpenPGP  andS/MIME email applications.  Finally, we propose mitigationstrategies to counter these attacks.
Y1  - 2019
UR  - https://www.usenix.org/conference/usenixsecurity19/presentation/muller
EP  - 18
ER  -