Publications

PHP filters chain: What is it and how to use it

18/10/2022 Searching for new gadget chains to exploit deserialization vulnerabilities can be tedious. In this article we will explain how to combine a recently discovered technique called PHP filters [LOKNOP-GIST], to transform file inclusion primitives in PHP applications to remote code execution. To support our explanations we will rely on a Laravel file inclusion gadget chains that was discovered during this research.

Persistent PHP payloads in PNGs: How to inject PHP code in an image – and keep it there !

10/10/2022 During the assessment of a PHP application, we recently came across a file upload vulnerability allowing the interpretation of PHP code inserted into valid PNG files. However, the image processing performed by the application forced us to dig deeper into the different techniques available to inject PHP payloads into this particular file format - and to make it persist through image transformations. These investigations allowed us to successfully exploit the vulnerability, and are summarized in this article.

Traces of Windows remote command execution

13/09/2022 A real ninja leaves no traces. However, in the Windows context, a lot of information are disseminated when performing actions and can be leveraged by DFIR analysts. Focusing on remote command execution techniques used by attackers and red-teamers, this article aims to get a collection of artifacts that can collected by analysts.

Exploiting CVE-2022-24816: A code injection in the jt-jiffle extension of GeoServer

12/08/2022 During one of our assessments we came across a server running GeoServer version 2.17.2. This version is outdated and affected by multiple security vulnerabilities. Among those vulnerabilities, one looked more promising than the others: CVE-2022-24816. This vulnerability is a code injection flaw in jt-jiffle that leads to an unauthenticated remote code execution.

CVE-2022-31813: Forwarding addresses is hard

26/07/2022 A few weeks ago, version 2.4.54 of Apache HTTPD server was released. It includes a fix for CVE-2022-31813, a vulnerability we identified in mod_proxy that could affect unsuspecting applications served by an Apache reverse proxy. Let's see why it is rated as low in the software changelog and why it still matters. TL;DR: when in doubt, patch!

CCleaner forensics

20/06/2022 During a ransomware attack, right after the ransomware was launched, we noticed the use of CCleaner as an anti-forensic tool to cover the attacker’s action. The following article aims to explore some key features of this tool from a forensic perspective. We will see how to identify the items that have been deleted and how they could be recovered. We focused on the free desktop version v6.00.9727.

Ready For IT 2022: Back to attacks on new digital uses

08/06/2022 Thanks to Ready for IT organizers so we can shared a feedback regarding our incident response services (CSIRT Synacktiv) and red team activities. Below is a summary of the intervention.

The printer goes brrrrr!!!

25/05/2022 Network printers have been featured for the first time at Pwn2Own competition in Austin 2021. Three popular LaserJet printers were included in the completion: HP, Lexmark and Canon. During the event, we (Synacktiv) managed to compromise all of them allowing us to win the whole competition. In this post, we will focus on how we achieved code execution on the Canon printer.

The reverse-engineering team presentation

13/04/2022 A lot of candidates, or simply fellow reversers, ask us how our team usually works: what kind of technologies are we looking into? What kind of projects? Do we work solo? How do we handle remote? etc. The goal of this blogpost is to share what we can about our internals, so you don't have to reverse us.

elFinder: The story of a repwning

30/03/2022 We recently identified a path traversal issue in the elFinder software. It is assigned CVE identifier CVE-2022-26960. While the vulnerability is pretty classical, the story of its discovery is not. Keep on reading for the details.