Kernel exploitation – r0 to r3 transitions via KeUserModeCallback
Hey there!
I have recently came across (well, not entirely by myself... cheers Nahuel!) a fairly (un)common problem related to performing ring0-to-ring3 transitions, after a successful kernel vulnerability exploitation. As I have managed to come up with a bunch of possible solutions, and even write exemplary code for some of these, today I would like to present my thoughts, together with some brief explanation.
Windows CSRSS Write Up: Inter-process Communication (part 2/3)
A quick beginning note: My friend d0c_s4vage has created a technical blog and posted his first text just a few days ago. The post entry covers a recent, critical libpng vulnerability discovered by this guy; the interesting thing is that, among others, the latest Firefox and Chrome versions were vulnerable. Feel free to take a minute and read the article here.
Additionally, the video and mp3 recordings from the presentation performed by me and Gynvael on the CONFidence 2010 conference, are now publicly available on the official website: link (Case study of recent Windows vulnerabilities).
Windows CSRSS Write Up: Inter-process Communication (part 1/3)
In the second post of the Windows CSRSS Write Up series, I would like to explain how the practical communication between the Windows Subsystem and user's process takes place under the hood. Due to the fact that some major improvements have been introduced in Windows Vista and later, the entire article is split into two parts - the first one giving an insight at what the communication channel really is, as well as how is it taken advantage of by both CSRSS and a user processes. The second one, on the other hand, is going to talk through the modifications and new features shipped with the Windows systems starting from Vista, as most of the basic ideas remain the same for decades. As you already know what to expect, proceed to the next section 
Windows CSRSS Write Up: the basics (part 1/1)
NOTE: The following post entry opens a series of CSRSS-oriented articles, aiming at describing the uncovered CSRSS mechanism internals, present in the Windows OS for more than fifteen years now. Although some great research has already been carried out by a few curious guys (check out the references), no thorough case study is available until now. In this series, I am going to cover both the very basic ideas and their implementations, as well as the recent CSRSS changes applied in modern operating systems (i.e. Windows 7). And so, just have a good read! 
CONFidence 2010 is over
One of the biggest (best ) IT security-oriented conferences in Poland finished three days ago, in the wednesday evening. In the very first place, I would like to congratulate all the organisers, for their decision on where the event should be held, as well as how it should look like - during these two days, I had plenty of real fun!
Windows CSRSS cross-version API Table
Hello!
It seems like half a year has passed since I published the Win32k.SYS system call table list on the net. During this time (well, it didn't take so long ) I managed to gather enough information to release yet another API list - this time, concerning an user-mode application - CSRSS (Client/Server Runtime SubSystem). As a relatively common research subject, I think a table of this kind can make things easier for lots of people.
CTcpFwd – cross-platform stdin/out to socket forwarding class
Hello,
A few weeks ago, I had the pleasure to take part in a local 24-hour long, programming marathon (greets to my team: Pawel and Wojtek!). Due to the nature of the competition, I was obliged to create a simple class, making it possible to redirect sockets to standard i/o (stdin / stdout), which would greatly facilitate the communication process with the contest server. Because of the fact that we were going to work on different system platforms - both Microsoft Windows and GNU/Linux, the class had to be as cross-platform compatible as it was only possible. And so the CTcpFwd class, presented today, came into existence.
“Descriptor tables in kernel exploitation” – a new article
Hi there!
Not so long (a few weeks, actually) ago, me together with Gynvael Coldwind had a chance to carry out a research regarding the Global and Local Descriptor Tables being used as a write-what-where target, while exploiting ring-0 vulnerabilities on 32-bit Microsoft Windows NT-family systems. The result of our work is a small article, describing the actual steps taken in order to escalate the privileges through GDT/LDT. As usual, exemplary source code snippets are available (attached to the document), so that the reader can check their effectiveness on his own.
x86 Kernel Memory Space Visualization (KernelMAP v0.0.1)
What I would like to write about today is a subject I have been playing with for quite some time – Windows kernel vulnerability exploitation techniques. While digging through various articles and other materials, I appeared to find bunches of interesting facts that are worth being described here. The post presented today aims to describe various ways of obtaining kernel-mode addresses from the user-mode (application) level.
Controlling Windows process list, part 1
First of all, I would like to point out that my old bootkit presentation related stuff is available since a few weeks now. As the whole event was held in polish language, so are the slides / materials. One way or another, if some of you were interested, just take a look at the Slow kilka o SecDay 2k9 post entry.
In one of my previous posts (check Suspending processes in Windows, part 1), I was trying to discuss the well-known and less popular techniques making it possible to suspend threads or entire processes working under Microsoft Windows OS control. I also announced that a specific way of TaskMgr.exe modification - extending it with the interesting functionality - would be described in the next post. Although, before getting straight to the point (this is - changing the executable binary code), we have to consider some other important matters. Namely, we intend to have the modification applied to every single Task Manager instance running on the system. Right here, we have a few possible paths to go:
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- Windows CSRSS Write Up: Inter-process Communication (part 1/3)
- Windows CSRSS Write Up: the basics (part 1/1)
Recent Comments
- j00ru: @Ivanlef0u: Hey. As for the first question, well… there is no particular reason for using...
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