{"id":2852,"date":"2017-01-13T16:52:28","date_gmt":"2017-01-13T16:52:28","guid":{"rendered":"https:\/\/www.rsoftsolution.com\/blog\/encrypted-messaging-platform-whatsapp-denies-backdoor-claim.html"},"modified":"2017-01-13T16:52:28","modified_gmt":"2017-01-13T16:52:28","slug":"encrypted-messaging-platform-whatsapp-denies-backdoor-claim","status":"publish","type":"post","link":"https:\/\/www.rbsitsoftwaresolution.in\/blog\/encrypted-messaging-platform-whatsapp-denies-backdoor-claim.html","title":{"rendered":"Encrypted messaging platform WhatsApp denies \u201cbackdoor\u201d claim"},"content":{"rendered":"


\n<\/p>\n

A security issue\u00a0has been flagged\u00a0in the hugely popular mobile messaging app WhatsApp that\u00a0could allow for messages sent via the encrypted platform to be intercepted and read.<\/p>\n

The Guardian<\/a>\u00a0report, which describes the vulnerability as a \u201cbackdoor\u201d, notes that independent\u00a0security researcher Tobias Boelter<\/a>\u00a0identified the issue\u00a0in April 2016, when he says he reported it to Facebook, only to be told it was \u201cexpected behavior\u201d, and that the company was not\u00a0actively working on fixing it. The newspaper\u00a0says it has verified the vulnerability still exists.<\/p>\n

Despite being a mainstream messaging app, WhatsApp has gained praise from security experts for implementing the respected end-to-end encryption Signal Protocol across its platform \u2014 completing its\u00a0roll out of end-to-end encryption in April last year<\/a>.\u00a0Yet\u00a0the company\u2019s code remains closed source, which means users have always been\u00a0required to trust its claims with no\u00a0ability for external audits of its code (although it\u2019s also worth noting that WhatsApp did work with Open Whisper Systems (OWS), the organization behind the\u00a0Signal Protocol, to implement the e2e\u00a0crypto across the\u00a0platform).<\/p>\n

The security issue identified by Boelter<\/a>, and reported on by the Guardian now following him\u00a0giving a talk about it at the end of last month, concerns an aspect of WhatsApp\u2019s Signal implementation that allows it\u00a0to\u00a0force the generation of new encryption keys for offline users. This is described as a \u201cretransmission vulnerability\u201d by Boelter, and claimed as a route for messages to be intercepted and read \u2014 and thus as a potential backdoor in WhatsApp\u2019s end-to-end encryption.<\/p>\n

However WhatsApp denies the backdoor\u00a0characterization, saying it\u2019s a design decision relating to message delivery, with\u00a0new keys being\u00a0generated for offline users in order to ensure messages don\u2019t get lost in transit.<\/p>\n

\u201cThe Guardian posted a story this morning claiming that an intentional design decision in WhatsApp that prevents people from losing millions of messages is a \u201cbackdoor\u201d allowing governments to force WhatsApp to decrypt message streams. This claim is false,\u201d said a\u00a0company\u00a0spokesperson in a statement sent to TechCrunch.<\/p>\n

\u201cWhatsApp does not give governments a \u201cbackdoor\u201d into its systems and would fight any government request to create a backdoor. The design decision referenced in the Guardian story prevents millions of messages from being lost, and WhatsApp offers people security notifications to alert them to potential security risks. WhatsApp published a technical white paper on its encryption design, and has been transparent about the government requests it receives, publishing data about those requests in the Facebook Government Requests Report,\u201d it added.<\/p>\n

WhatsApp\/Facebook details its responses to government requests for data here<\/a>.<\/p>\n

Multiple security commentators have also pointed out that\u00a0the vulnerability being flagged\u00a0here is nothing new<\/a> \u2014 but rather a rehashing of the long-standing issue of how\u00a0key verification is implemented\u00a0within an encrypted system.<\/p>\n

\n

Key verification is a hard usability problem. Efforts like Key Transparency CONIKS can help make this less painfulhttps:\/\/t.co\/H7Ptvh5Djg<\/a><\/p>\n

\u2014 Frederic Jacobs (@FredericJacobs) January 13, 2017<\/a><\/p>\n<\/blockquote>\n

\n

In an earlier statement WhatsApp pointed out that\u00a0its implementation of the Signal protocol includes an optional \u201cShow Security Notifications\u201d setting that will notify a user\u00a0when a contact\u2019s security code\u00a0has changed \u2014 thereby\u00a0allowing\u00a0users to\u00a0opt in to be notified when\/if a key has been changed (and thus when\/if there\u2019s a risk of their\u00a0messages being man-in-the-middle intercepted).<\/p>\n

At the time of WhatsApp completing its implementation of the Signal Protocol, OWS\u2019 Moxie Marlinspike also explained that\u00a0the implementation\u00a0offers users an\u00a0\u201copt in to a preference which notifies them every time the security code for a contact changes\u201d.<\/p>\n

He\u00a0also pointed to a white paper on the WhatsApp Signal Protocol implementation which further states: \u201cWhatsApp servers do not have access to the private keys of WhatsApp users, and WhatsApp users have the option to verify keys in order to ensure the integrity of their communication.\u201d<\/p>\n

In the same\u00a0blog post<\/a> Marlinspike argued\u00a0that WhatsApp users would now get \u201call the benefits\u201d of \u201ca modern, open source, forward secure, strong encryption protocol<\/a>\u00a0for asynchronous messaging systems, designed to make end-to-end encrypted messaging as seamless as possible\u201d. The Facebook-owned messaging platform has\u00a0more than a\u00a0billion monthly active users<\/a>\u00a0at this point.<\/p>\n

In an email to TechCrunch, Katriel Cohn-Gordon, one of the group of international security researchers\u00a0who\u00a0audited the Signal Protocol<\/a>\u00a0described the security issue flagged by\u00a0Boelter as \u00a0\u201cnontrivial\u201d \u2014 but did not\u00a0go so far as to call\u00a0it as a backdoor.<\/p>\n

For clarity, the group\u2019s analysis of the Signal Protocol found the underlying<\/em> protocol\u00a0to be lacking in any logical errors but did not study the security of the implementation of the protocol. And its WhatsApp\u2019s\u00a0implementation of Signal that people are quibbling about here.<\/p>\n

Whether WhatsApp\u2019s\u00a0key verification process\/\u201dnontrivial\u201d bug is an intentional security backdoor or a design decision with a user opt-out depends on your perspective. But arguably the platform\u2019s\u00a0biggest security flaw remains\u00a0not open sourcing its code to allow for external audits \u2014 not least given that its parent company, Facebook, has a business model based on monetizing the personal information of users via profiling their preferences and targeting them with ads.<\/p>\n

Alan Duric, co-founder and CTO at another mobile messaging app Wire, whose end-to-end crypto, proteus is\u00a0open sourced<\/a>\u00a0\u2014 and is also based on axolotl, the forerunner to the Signal Protocol \u2014 wastes no time in pointing out that outsiders can test\u00a0its security claims, unlike WhatsApp\u2019s, which they rather have to take on trust.<\/p>\n

\u201cWire does not regenerate encryption keys,\u201d he tells TechCrunch. \u201cOnce the key fingerprints have been verified by users changes in keys will be detected on both ends and shown to the users. Wire is transparent in how it works and because all code is open sourced it doesn\u2019t take 8 months to discover, disclose and fix security issues.\u201d<\/p>\n

\u201cBy embracing open source we are always a step ahead of situations like these as there are thousands of developers who\u2019ve looked at our code in GitHub and many have analysed it in more depth,\u201d he adds.<\/p>\n

We asked Boelter for his views on whether the retransmission vulnerability was created intentionally by WhatsApp, i.e. to be a backdoor for access to data (whether for Facebook\u00a0or government agencies to access); or an accidental byproduct of its\u00a0design decisions vis-a-vis message delivery \u2014 and he argues both sides.<\/p>\n

\u201cIf someone would demand WhatsApp to implement a backdoor, you might expect them to implement something more obvious. Like responding with the history of all conversations when triggered to so do with a certain secret message. Furthermore, this flaw can be explained as a programming bug. Just a missed \u201cif\u201d statement for one of the corner cases. It is a type of flaw that is not necessarily introduced by malice,\u201d he says.<\/p>\n

\u201cHowever, Facebook showed no interest in fixing the flaw since I reported it to them in April 2016. So maybe it was a bug first, but when discovered it got started being used as a backdoor WhatsApp has stated recently that this is not a bug, it is a feature! Because now senders don\u2019t have to press an extra \u2018OK\u2019 button in the rare case they sent a message, the receiver is offline and has a new phone when coming back online.<\/p>\n

\u201cThat\u2019s not a very good argument! And if \u201cPrivacy and Security is in [WhatsApp\u2019s] DNA\u201d, they should have fixed the flaw immediately after I reported it in April 2016.\u201d<\/p>\n

Boelter further noted that while the\u00a0WhatsApp server can re-announce the \u201cold, correct, private key of the recipient to the sender\u201d \u2014 i.e. if the sender has opted in to receive the \u201cSecurity Code has changed\u201d notifications \u2014\u00a0the conversation can still continue uninterruptedly. So it relies on users both noticing and understanding the privacy risk implication of the notification, given that communication after a key has changed is not actively blocked by WhatsApp (as it is by the Signal messaging app, for example).<\/p>\n

\u201cWhatsApp can also opt to correctly deliver messages for a while without informing the sender that the messages have been delivered correctly. And only after a while trigger the key-switch,\u201d he adds.<\/p>\n

Which\u00a0secure messaging app does Boelter recommend using?\u00a0\u201cI use Signal,\u201d he says. \u201cSignal is open source. Signal makes an effort to have reproducible builds. Signal claims to store much less metadata on their servers than WhatsApp allows itself in their privacy policy. And Signal is just as easy to use as WhatsApp.\u201d<\/p>\n

In his April analysis of WhatsApp\u2019s Signal implementation, Boelter also wrote: \u201cProprietary closed-source crypto software is the wrong path. After all this \u2014 potentially malicious code \u2014 handles all our decrypted messages. Next time the FBI will not ask Apple but WhatsApp to ship a version of their code that will send all decrypted messages directly to the FBI.\u201d<\/p>\n

<\/p>\n

Article source: http:\/\/feedproxy.google.com\/~r\/techcrunch\/social\/~3\/_LV0sm6fTss\/<\/p>","protected":false},"excerpt":{"rendered":"

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