At Quarkslab, we don't only break software and exploit vulnerabilities, we also try to create innovative and efficient solutions to counter them. Cappsule is one of those solutions.

Obfuscation is made of many different tricks. One we meet very often is mixed instructions who make computations mixing usual arithmetic (ADD, SUB, MUL, DIV) and boolean one (XOR, AND, NOT, OR). All tools get lost when it comes to cleaning this kind of very messy blocks of instructions, and that is why we designed Arybo. With Arybo, analyzing such expressions become way more easy.

This is the last part of our blogpost series about Xen security [1] [2]. This time we write about a vulnerability we found (XSA-182) [0] (CVE-2016-6258) and his exploitation on Qubes OS [3] project.

This blog post describes the exploitation of Xen Security Advisory 148 (XSA-148) [1] (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 [6] and will give conferences explaining his approach [7]. 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) [1] (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.