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{ Category Archives } undocumented api

Windows Kernel Local Denial-of-Service #3: nt!NtDuplicateToken (Windows 7-8)

This is the third post in a series about unpatched local Windows Kernel Denial-of-Service bugs. The list of previous posts published so far is as follows: Windows Kernel Local Denial-of-Service #2: win32k!NtDCompositionBeginFrame (Windows 8-10) Windows Kernel Local Denial-of-Service #1: win32k!NtUserThunkedMenuItemInfo (Windows 7-10) As opposed to the two issues discussed before, today’s bug is not in the graphical […]

Windows Kernel Local Denial-of-Service #2: win32k!NtDCompositionBeginFrame (Windows 8-10)

Another week, another way to locally crash the Windows kernel with an unhandled exception in ring-0 code (if you haven’t yet, see last week’s DoS in win32k!NtUserThunkedMenuItemInfo). Today, the bug is in the win32k!NtDCompositionBeginFrame system call handler, whose beginning can be translated into the following C-like pseudo-code: NTSTATUS STDCALL NtDCompositionBeginFrame(HANDLE hDirComp, PINPUT_STRUCTURE lpInput, POUTPUT_STRUCTURE lpOutput) […]

Windows Kernel Local Denial-of-Service #1: win32k!NtUserThunkedMenuItemInfo (Windows 7-10)

Back in 2013, Gynvael and I published the results of our research into discovering so-called double fetch vulnerabilities in operating system kernels, by running them in full software emulation mode inside of an IA-32 emulator called Bochs. The purpose of the emulation (and our custom embedded instrumentation) was to capture detailed information about accesses to user-mode memory […]

Slides about my Windows Metafile research (Ruxcon, PacSec) and fuzzing (Black Hat EU) now public

During the past few weeks, I travelled around the world to give talks at several great security conferences, such as Ruxcon (Melbourne, Australia), PacSec (Tokyo, Japan), Black Hat Europe (London, UK) and finally Security PWNing Conference (Warsaw, Poland). At a majority of the events, I presented the results of my Windows Metafile security research, which […]

Windows system call tables updated, refreshed and reworked

Those of you interested in the Windows kernel-mode internals are probably familiar with the syscall tables I maintain on my blog: the 32-bit and 64-bit listings of Windows system calls with their respective IDs in all major versions of the OS, available here (and are also linked to in the left menu): Windows Core (NT) […]

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 […]

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 […]

Windows System Call and CSR API tables updated

Having the first spare weekend in a really long time, I have decided it was high time to update some (all) of the tables related to Windows system calls and CSR API I once created and now try to maintain. This includes NT API syscalls for the 32-bit and 64-bit Intel platforms, win32k.sys syscalls for […]

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 […]