Direkt zum Hauptbereich

How Secure is TextSecure?

Instant Messaging has attracted a lot of attention by users for both private and business communication and has especially gained popularity as low-cost short message replacement on mobile devices. However, most popular mobile messaging apps do not provide end-to-end security. Press releases about mass surveillance performed by intelligence services such as NSA and GCHQ lead many people looking for means that allow them to preserve the security and privacy of their communication on the Internet. Additionally fueled by Facebook's acquisition of the hugely popular messaging app WhatsApp, alternatives that claim to provide secure communication experienced a significant increase of new users.

A messaging app that has attracted a lot of attention lately is TextSecure an app that claims to provide secure instant messaging and has a large number of installations via Google's Play Store. It's protocol is part of Android's most popular aftermarket firmware CyanogenMod. In a paper we have recently uploaded on eprint, we present the first complete description of TextSecure's complex cryptographic protocol and are the first to provide a thorough security analysis of TextSecure. Among other findings, we present an Unknown Key-Share Attack on the protocol, along with a mitigation strategy. Furthermore, we formally prove that---if our mitigation is applied---TextSecure's push messaging can indeed achieve the goals of authenticity and confidentiality.

After the first upload the paper received much attention. A discussion started, e.g., on the ModernCrypto Mailing List, at Reddit and at Hacker News. We posted a response on the former discussion on Medium.

The paper gets also mentioned in many non-technical articles, most of which appreciate our research, e.g., heisec.de, TheRegister and Softpedia and is taken into considerations by the Electronic Frontier Foundation for their Secure Messaging Scorecard.

Beliebte Posts aus diesem Blog

Printer Security

Printers belong arguably to the most common devices we use. They are available in every household, office, company, governmental, medical, or education institution.
From a security point of view, these machines are quite interesting since they are located in internal networks and have direct access to sensitive information like confidential reports, contracts or patient recipes.

TL;DR: In this blog post we give an overview of attack scenarios based on network printers, and show the possibilities of an attacker who has access to a vulnerable printer. We present our evaluation of 20 different printer models and show that each of these is vulnerable to multiple attacks. We release an open-source tool that supported our analysis: PRinter Exploitation Toolkit (PRET) https://github.com/RUB-NDS/PRET Full results are available in the master thesis of Jens Müller and our paper. Furthermore, we have set up a wiki (http://hacking-printers.net/) to share knowledge on printer (in)security.
The hi…

How to Break Microsoft Rights Management Services

In this post, we provide a security analysis of Microsoft Rights Management Services (RMS) and present two working attacks:  We completely remove the RMS protection of a Word document on which we only have a view-only permission, without having the right to edit it. This shows that in contrast to claims made by Microsoft, Microsoft RMS can only be used to enforce all-or-nothing access. We extend this attack to be stealthy in the following sense: We show how to modify the content of an RMS write-protected Word document issued by our victim. The resulting document still claims to be write protected, and that the modified content was generated by the victim This work is going to be presented at WOOT'16.