Publications

Advent ctf 2019 overthewire - day2 writeup

05/01/2020 The advent ctf organized by overthewire proposed various challenges that would unlock on a daily basis (like an advent calendar). I found day number 2 (made by hpmv) quite challenging and super fun to solve! It involved crypto, network and rev in a blackbox environment. The full source code used to solve this challenge is available here https://github.com/majin42/adventctf_otw_day2

FIC2020 prequals CTF write-up

19/12/2019 We took part to FIC2020's prequals CTF, organized by the French team Hexpresso with a team made of @dzeta, @laxa, @swapgs and @us3r777. We managed to finish second, so here is our writeup!

Pwning an outdated Kibana with not so sad vulnerabilities

12/12/2019 During a recent engagement, we came across an old outdated instance of the Kibana software. It was affected by two severe public vulnerabilities (CVE-2018-17246 and CVE-2019-7609). However, in the context, none of them was readily exploitable. In this article, we describe how we managed to takeover the software all the same, with a new exploitation technique. Don't expect any 0-dayz dropping in the following, only a new way to exploit two already known issues.

Binder Secctx Patch Analysis

11/10/2019 In the beginning of 2019, a new feature was added in the Binder kernel module. This patch allows to send the caller SElinux context in a Binder transaction. This feature was in fact a fix for CVE-2019-2023. This vulnerability is related to an unsafe use of the getpidcon function, leading to ACL bypass. This article studies details of this patch and its impact on security.

Scraps of Notes on Exploiting Exim Vulnerabilities

08/10/2019 Recently, Qualys published an advisory about a severe vulnerability impacting Exim MTA: CVE-2019-15846. In their report, they even claim that they do have a PoC granting a remote attacker root privileges. The report was followed by instant alarmist articles: "Millions of Exim servers vulnerable to ..."

BFS 2019 Exploitation Challenge

17/09/2019 On September 7th, 2019, BFS published an exploitation challenge on Windows 10 x64 to win an entry for the BFS-IOACTIVE party during the Ekoparty conference. This blogpost aims at describing a successful resolution of the challenge.

"No grave but the SIP": Reversing a VoIP phone firmware

30/08/2019 When conducting internal intrusion tests, one can find interesting to access the phones used by a client, as they are often connected to an internal network and can provide some kind of persistent access. This article presents the research done for getting a good grasp on the firmware of Yealink VoIP phones, which enables us to analyze further the underlying system.

2019 summer challenge writeup

30/07/2019 The 2019 summer challenge is now closed! This was a bit of a departure from the usual hardened binaries, as it showcased a programming model that is not a distant relative of the Turing machine. This article will give a high level overview of the challenge's solution, and some behind-the scenes comments.

Exploiting a No-Name FreeBSD Kernel Vulnerability

24/07/2019 A new patch has been recently shipped in FreeBSD kernels to fix a vulnerability (cve-2019-5602) present in the cdrom device. In this post, we will introduce the bug and discuss its exploitation on pre/post-SMEP FreeBSD revisions.

2019 summer challenge: Alonzo!

18/06/2019 The Synacktiv summer challenge is back!