This blog post describes the exploitation of Xen Security Advisory 148 (XSA-148) (CVE-2015-7835). It has been discovered by Shangcong Luan of Alibaba and publicly disclosed in October 2015. At the time, we were working on writing an exploit and no public proof of concept nor exploit were available. Today, the security researcher responsible of the vulnerability disclosure has given a public talk and will give conferences explaining his approach . We decided to publish this blogpost anyway because our exploitation strategy is a little bit different.

When appointing computation of private data to a third party, privacy is an issue. How can one delegate computation without giving up one's secrets? This gets trickier when multiple parties are involved. Several works on Multi-Party Computation (MPC) addressed this issue, but a new approach has started to emerge: Fully Homomorphic Encryption (FHE).

This blog post describes the exploitation of Xen Security Advisory 105 (XSA-105) (CVE-2014-7155). This post explains the environment setup and shows the development of a fully working exploit on Linux 4.4.5.

An optimization for the finite field multiplication on 128-bit elements for AES-GCM exists whose explanation was not published, preventing any further application with different parameters. We reverse engineered the result to 1) get the explanation and 2) be able to apply it with other parameters.

HOW-TO: Implementing a custom directive processor in clang to drive the compilation process of our LLVM-base code obfuscator, while maintaining backward-compatibility if another compiler is used. What a good opportunity for a journey in the first compiler stages!

Open sourcing binmap, a tool to scan filesystem and gather intel on which binaries are there, what are their dependencies, which symbols they are using and more. This yields a global view of a system, providing the basic block for building other tools!

Since Windows XP SP2, the Windows firewall is deployed and enabled by default in every Microsoft Windows operating system. Starting with Windows Vista the firewall relies on a set of API and services called the Windows Filtering Platform (WFP). Although used by almost every Windows OS, WFP is still one of the relatively unknown beast that lies in the kernel. In this post we will see how the firewall manages its persistent state.

This post deals with the new features in IRMA 1.3.0 released earlier this month, from both a user and a contributor point of view.

While improving the documentation (d'oh!) of our home grew obfuscator based on LLVM, we wrote a cheat sheet on clang's hardening features, and some of ld ones. It turns out existing hardening guides generally focus on GCC, while Clang also has an interesting set of hardening features. So let's share it in this blog post!

Chaque saison, des nuées de stagiaires quittent les réconfortants bancs de l'école pour rejoindre le monde sans pitié du travail. Afin de faciliter cette transition, nous, à Quarkslab, proposons des stages avec des sujets pointus, un encadrement sans complaisance mais néanmoins chaleureux, un régime alimentaire digne de sportifs de haut niveau (indispensable pour tenir le rythme), et un humour imperméable aux blagues qui ne font pas toujours un tabac. Si toi aussi tu aimes les défis, engage toi avec nous !