A security backdoor that can be used to allow Facebook and others to intercept and read encrypted messages has been found within its WhatsApp messaging service, The Guardian reports.
Facebook claims that no one can intercept WhatsApp messages, not even the company and its staff, ensuring privacy for its billion-plus users. But new research shows that the company could in fact read messages due to the way WhatsApp has implemented its end-to-end encryption protocol.
Privacy campaigners said the vulnerability is a “huge threat to freedom of speech” and warned it can be used by government agencies to snoop on users who believe their messages to be secure. WhatsApp has made privacy and security a primary selling point, and has become a go to communications tool of activists, dissidents and diplomats.
The security backdoor was discovered by Tobias Boelter, a cryptography and security researcher at the University of California, Berkeley. He told the Guardian: “If WhatsApp is asked by a government agency to disclose its messaging records, it can effectively grant access due to the change in keys.”
Boelter reported the backdoor vulnerability to Facebook in April 2016, but was told that Facebook was aware of the issue, that it was “expected behaviour” and wasn’t being actively worked on. The Guardian has verified the backdoor still exists.
Steffen Tor Jensen, head of information security and digital counter-surveillance at the European-Bahraini Organisation for Human Rights, verified Boelter’s findings. He said: “WhatsApp can effectively continue flipping the security keys when devices are offline and re-sending the message, without letting users know of the change till after it has been made, providing an extremely insecure platform.”
Boelter said: “[Some] might say that this vulnerability could only be abused to snoop on ‘single’ targeted messages, not entire conversations. This is not true if you consider that the WhatsApp server can just forward messages without sending the ‘message was received by recipient’ notification (or the double tick), which users might not notice. Using the retransmission vulnerability, the WhatsApp server can then later get a transcript of the whole conversation, not just a single message.”
The vulnerability calls into question the privacy of messages sent across the service, which is used around the world, including by people living in oppressive regimes.
A WhatsApp spokesperson told the Guardian: “Over 1 billion people use WhatsApp today because it is simple, fast, reliable and secure. At WhatsApp, we’ve always believed that people’s conversations should be secure and private. Last year, we gave all our users a better level of security by making every message, photo, video, file and call end-to-end encrypted by default. As we introduce features like end-to-end encryption, we focus on keeping the product simple and take into consideration how it’s used every day around the world.
Asked to comment specifically on whether Facebook/WhatApps had accessed users’ messages and whether it had done so at the request of government agencies or other third parties, it directed the Guardian to its site that details aggregate data on government requests by country.
Facebook halted the use of the shared user data for advertising purposes in November after pressure from the pan-European data protection agency groupArticle 29 Working Party in October. The European commission then filed charges against Facebook for providing “misleading” information in the run-up to the social network’s acquisition of messaging service WhatsApp, following its data-sharing change.