\n
![](\"https:\/\/i0.wp.com\/www.rsoftsolution.com\/blog\/wp-content\/plugins\/RSSPoster_PRO\/cache\/f4c5d_p1040870.jpg?w=640&ssl=1\")
<\/p>\n
\n<\/p>\n
Security can be a fractious space, with\u00a0claim and counterclaim flying as rivals\u00a0jockey for\u00a0position\u00a0and to achieve reputational robustness. Cutting through the\u00a0noise can be impossible without outside expertise, which is why it\u2019s so valuable to have an expert audit\u00a0of a security\u00a0product.<\/p>\n
To wit: encrypted messaging app Wire<\/a> has now published an external\u00a0audit<\/a> of its crypto protocol, Proteus, and the implementation of the\u00a0protocol across its various apps.<\/p>\n It\u2019s a paid audit,\u00a0conducted for Wire by two security researchers, Jean-Philippe\u00a0Aumasson from\u00a0Kudelski Security<\/a>, and Markus Vervier from\u00a0X41 D-Sec<\/a>.<\/p>\n In a Medium post<\/a> detailing the review, Wire\u00a0writes: \u201cThe review covers Proteus implementation in all platforms where Wire is available\u200a \u2014 \u200aiOS, Android, macOS, Windows, Linux, and Wire for Web that works in modern, webRTC-supported browsers.\u201d<\/p>\n An outside audit is perhaps especially valuable for Wire at this point as it took some flak recently following\u00a0a critical blog post<\/a> which was shared via Twitter\u00a0and drew\u00a0the attention of the security community.<\/p>\n Wire rejected the criticisms and argued<\/a> it was being unfairly targeted by anonymous accounts\u00a0posting on social media. TechCrunch contacted the\u00a0writer of the original critical post who is named on Medium as\u00a0Tina Membe<\/a>, but the\u00a0person would\u00a0not divulge his or her\u00a0identity to us\u00a0\u2014 only qualifying themselves as\u00a0\u201cnot really a security researcher\u201d.<\/p>\n That said, the person\u00a0stood by their criticism\u00a0of Wire\u2019s code, describing it as \u201cvery messy\u201d and specifically criticizing how Wire performs certificate pinning \u2014 arguing their method\u00a0is\u00a0flawed because it\u00a0could be bypassed by state-level attackers.<\/p>\n \u201cOne example, the code enables \u2018pinning\u2019 only if the \u2018subject alternative name\u2019 of the certificate matches http:\/\/wire.com<\/a> or ends with http:\/\/wire.com,\u201d<\/a> they told us, pointing to this part of Wire\u2019s code<\/a>. \u201cBut \u2018subject alternative name\u2019 is optional in certificates. Attacker would issue a certificate for \u2018common name\u2019 of http:\/\/wire.com<\/a> from any CA (China, Tunisia, Turkey, etc) omit \u2018subject alternative name\u2019 and this would consider it valid.<\/p>\n \u201cI think this is a very obvious mistake, a real security researcher could verify for you,\u201d they added.<\/p>\n Wire\u2019s security reviewers did identify\u00a0some issues with the software \u2014 including a bug allowing invalid public keys to be transmitted and processed without being flagged as an error. But the reviewers\u00a0also describe the reviewed components as having \u201ca high security, thanks to state-of-the-art cryptographic protocols and algorithms, and software engineering practices mitigating the risk of software bugs\u201d.<\/p>\n The review covered Wire\u2019s\u00a0protocol specification and protocol implementation. More specifically,\u200athe implementation of its\u00a0Proteus messaging protocol<\/a> and Cryptobox<\/a> API and its C wrapper Cryptobox-C<\/a>. \u201cCryptobox defines a simple, high-level API to Proteus in order to hide the protocol\u2019s complexity to callers in Wire applications,\u201d is Wire\u2019s\u00a0explainer of that component.<\/p>\n The review also included CoffeeScript counterparts of Proteus and cryptobox as implemented in the proteus.js<\/a> and cryptobox.js<\/a>.<\/p>\n A third layer of security review \u2014 considering\u00a0the complete solution in the round \u2014 remains ongoing, according to Duric.<\/p>\n In their overview of the audit, the external security reviewers write:<\/p>\n The components reviewed were found to have a high security, thanks to state-of-the-art cryptographic protocols and algorithms, and software engineering practices mitigating the risk of software bugs. Issues were nonetheless found, with some of them potentially leading to a degraded security level. None of the issues found is critical in terms of security. We for example found that invalid public keys could be transmitted and processed without raising an error. As a consequence, the shared secret negotiated by communicating parties becomes predictable, which in turns weakens security guarantees in terms of \u201cbreak-in recovery\u201d. The root cause of this issue is a bug in a third-party component (neglect to verify an error code). We recommend that this issue be fixed, and that other security improvements be implemented to address thread-unsafety risks, sensitive data in memory, and other aspects as described in this report.<\/p>\n<\/blockquote>\n Wire\u00a0says it has fixed all issues identified by the review and deployed the fixes on iOS and Android, and is in the process of deploying on Wire for web and its desktop apps.<\/p>\n It goes without saying that\u00a0for any security product\u00a0perceptions of insecurity\u00a0can do real and lasting damage. So Wire\u00a0will clearly be hoping that an external\u00a0review of its crypto helps to dispel\u00a0some of the criticisms it has attracted \u2014 and Duric was quick to point us to a sample\u00a0early assessment of the audit from a\u00a0security academic:<\/p>\n \u201cKudelski is independent reviewer,\u201d Duric\u00a0added, via email, of the firm paid to carry out the audit. \u201cCompany with long tradition in the field and experts that concluded review are among leading experts in the field.\u201d<\/p>\n Katriel Cohn-Gordon, one of the group of academic\u00a0security researchers\u00a0who\u00a0audited the Signal Protocol<\/a>\u00a0\u2014 which powers the eponymous Signal encrypted messaging app \u2014 also welcomed Wire\u2019s move. \u201cIt\u2019s good to see companies like Wire being transparent about their security,\u201d he wrote\u00a0in an email to TechCrunch. \u201c[The audit] seems well-written and Wire\u2019s prompt response is a good sign.\u201d<\/p>\n It\u2019s worth noting that while Signal\u2019s protocol is not the same as Wire\u2019s Proteus protocol, Wire did use some open source components written by the Signal Protocol\u2019s creator, Open Whisper Systems \u2014 and as a result its\u00a0Proteus protocol code displays a copyright attribution reflecting\u00a0this reuse.<\/p>\n \u00a0<\/p>\n Wire, which was founded in 2012 and is based in Switzerland, is backed by Skype co-founder Janus Friis. Although it started with more of a general communications\u00a0focus, it has since shifted to billing itself as a \u201cprivate messenger\u201d with a\u00a0\u201cfocus on privacy\u201d \u2014 expanding\u00a0end-to-end encryption across all\u00a0messaging types on its platform (not just calls) in March<\/a> last year.<\/p>\n Last\u00a0December <\/a>it also added a username option, meaning privacy-conscious users do not need to share their phone number or email in order to communicate with other Wire users.\u00a0And while the app remains\u00a0free Wire\u00a0says<\/a> it will be introducing paid services this year.<\/p>\n It\u00a0also says it is committing to regular external security reviews from here on in, as it continues to develop its apps.<\/p>\n \u201cGoing forward every major development at Wire will also include a security review,\u201d it writes. \u201cWe\u2019ll continue to partner with security experts like Kudelski Security and X41 D-Sec to work on a complete solution review.<\/p>\n\n