Skip to content

{ Category Archives } exploitation

Disclosing stack data (stack frames, GS cookies etc.) from the default heap on Windows

In the previous blog post, I discussed a modest technique to “fix” the default process heap in order to prevent various Windows API functions from crashing, by replacing the corresponding field in PEB (Process Environment Block) with a freshly created heap. This of course assumes that the attacker has already achieved arbitrary code execution, or is […]

Windows user-mode exploitation trick – refreshing the main process heap

During the weekend of May 21-23 (directly after the CONFidence CTF that we organized with Dragon Sector), qualifications to the famous DEF CON CTF 2016 took place. We obviously participated in what is probably the most binary heavy, challenging and competitive CTF of the year, eventually ending up 9th on the final scoreboard, which was sufficient […]

Details on a (not so recent now) stack-based buffer overflow in the Adobe CFF rasterizer in FreeType2 (CVE-2014-2240, CVE-2014-9659)

This blog has experienced a long time of inactivity, as I’ve recently used it only to publish slides from conferences I presented at, with many months-long breaks in between. I am planning to change things up and start posting again in the upcoming weeks, starting with this blog post, which I originally wrote in early 2014. I haven’t […]

44CON slides and details about further Windows kernel font vulnerabilities are out

Since my last blog post and the REcon conference in June, I have continued working on font security, especially in the area of Windows kernel and font engines derived from the Adobe Type Manager Font Driver. More specifically, I moved from manually auditing PostScript Charstring implementations to running automated fuzz-testing of the overall font-handling code; after […]

Results of my recent PostScript Charstring security research unveiled

Some months ago, I started reverse engineering and investigating the security posture of the Adobe Type Manager Font Driver (ATMFD.DLL) module, which provides support for Type 1 and OpenType fonts in the Windows kernel since Windows NT 4.0, and remains there up to this day in Windows 8.1. Specifically, I focused on the handling of […]

Insomni’hack 2015, presentation slide deck and CTF results

(Collaborative post by Gynvael Coldwind and Mateusz “j00ru” Jurczyk) Just three days ago another edition of the great Insomni’hack conference held in Geneva came to an end. While the event was quite short, lasting for just one day, it featured three tracks of security talks, including some very interesting ones such as Automotive security by […]

CONFidence 2014 slides from Dragon Sector are now available

(Collaborative post by Gynvael Coldwind and Mateusz “j00ru” Jurczyk) Just yesterday another edition of the largest and most successful IT security conference held in Poland – CONFidence – ended. The Dragon Sector CTF team (which we founded and are running) actively participated in the organization of the event by hosting an onsite, individual CTF for […]

A case of a curious LibTIFF 4.0.3 + zlib 1.2.8 memory disclosure

As part of my daily routine, I tend to fuzz different popular open-source projects (such as FFmpeg, Libav or FreeType2) under numerous memory safety instrumentation tools developed at Google, such as AddressSanitizer, MemorySanitizer or ThreadSanitizer. Every now and then, I encounter an interesting report and spend the afternoon diving into the internals of a specific […]

ZeroNights 2013 and NTVDM vulnerabilities

Just yesterday I had the pleasure to speak at a highly hacking-oriented Russian conference, ZeroNights, for the second time (see my “ZeroNights slides, Hack In The Box Magazine #9 and other news” post from last year). The conference itself has been great so far – several interesting and inspiring talks, lots of leet Russian hackers […]

Windows win32k.sys menus and some “close, but no cigar” bugs

Welcome after one of the more lengthy breaks in the blog’s activity. Today, I would like to discuss none other than several interesting weaknesses around the implementation of menus (like, window menus) in the core component of the Microsoft Windows kernel – the infamous win32k.sys driver, also known as the “Java of Windows” in terms […]