TLS in the wild: An Internet-wide analysis of TLS-based protocols for electronic communication Ralph Holz∗, Johanna Amannz, Olivier Mehaniy, Matthias Wachsx, Mohamed Ali Kaafary ∗University of Sydney, Australia, Email:
[email protected] yData61/CSIRO, Sydney, Australia, Email:
[email protected] zICSI, Berkeley, USA, Email:
[email protected] xTechnical University of Munich, Germany, Email:
[email protected] This is a preprint of the camera-ready version to appear at NDSS 2016. Last update: 19 Dec 2015. Abstract—Email and chat still constitute the majority of in 2018 [11]. As for chat, the most widely used standard- electronic communication on the Internet. The standardisation based networks are IRC group chats and the XMPP instant and acceptance of protocols such as SMTP, IMAP, POP3, XMPP, messaging and multi-user conferencing network. and IRC has allowed to deploy servers for email and chat in a decentralised and interoperable fashion. These protocols can be In their early days, email protocols such as SMTP, POP3, secured by providing encryption with TLS—directly or via the and IMAP were designed with no special focus on security. STARTTLS extension. X.509 PKIs and ad hoc methods can be In particular, authentication in SMTP was introduced a while leveraged to authenticate communication peers. However, secure after the protocol’s standardisation, initially as a way to configuration is not straight-forward and many combinations fight spam. User agents started to move towards encryption of encryption and authentication mechanisms lead to insecure deployments and potentially compromise of data in transit. In and authenticated connections gradually, using the then-new this paper, we present the largest study to date that investigates SSL 3 and later the TLS protocols to protect the transport the security of our email and chat infrastructures.