Filter Monitor 1.0.1

This week, after months of development of bigger projects, I found some time to windbg “ntoskrnl.exe” and write a utility. It is called Filter Monitor and shows some key filters installed by kernel mode components.

“As you probably all know the Service Descriptor Table has been a playground on x86 for all sorts of things: rootkits, anti-viruses, system monitors etc. On x64 modifying the Service Descriptor Table is no longer possible, at least not without subverting the Patch Guard technology.

Thus, programs have now to rely on the filtering/notification technologies provided by Microsoft. And that’s why I wrote this little utility which monitors some key filters.

Since I haven’t signed the driver of my utility, you have to press F8 at boot time and then select the “Disable Driver Signature Enforcement” option. If you have a multiple boot screen like myself, then you can take your time. Otherwise you have to press F8 frenetically to not miss right moment.

A disclaimer: the boot process can be a bit annoying, but the utility should be used on virtualized systems anyway, as I haven’t fully tested it yet. I doubt that it will crash your system, I guess the worst scenario is that it won’t list some filters. It should work on any Windows system starting from Vista RTM and I have provided an x86 version and an x64 version. But the truth is that I have tested only the x64 version on Windows 7 RTM. Last but not least, I can’t guarantee that this utility will work on future versions of Windows, it relies heavily on system internals.

Now, let’s run it. The supported filters/notifications at the time are these: Registry, Create Process, Create Thread and Load Image. “Registry” stands for CmRegisterCallback filters. “Create Process” for PsSetCreateProcessNotifyRoutine callbacks. “Create Thread” for PsSetCreateThreadNotifyRoutine callbacks. And “Load Image” for PsSetLoadImageNotifyRoutine callbacks.

The “Additional Info” in the list view provides internal information like the address of the callback function.

There are some default filters registered by system components, but, as you can notice, there are also Kaspersky components. That’s because some filters (like the registry filter) are not used by system components and I needed a tool which would make use of these filters for my little demonstration.

The version of Kaspersky I have installed is the latest one available on the internet which is: 9.0.0.463.

I created for this demonstration a little executable called “k-test” (what you see on the desktop are three copies of the same executable) which copies itself in a directory called “borda” in the “Roaming” directory of the operating system. It then creates a value in the Run key of the registry to execute itself at each start-up. Finally, it launches itself from the “Roaming” directory and ends.

This is a typical malware behavior. Beware that the signature of the application itself is not contained in the databases of Kaspersky as I have written it on the fly, but it detects the suspicious behavior, stops execution and deletes the file. And it does this every time I launch the test application.

Now let’s get to the part where I show an additional functionality of the Filter Monitor which is the ability to remove registered filters and see what happens if I remove the filters installed by klif.sys, which is the “Kaspersky Lab Interceptor and Filter” driver. As the name suggests, this driver intercepts and filters: it installs all four of typologies of filters listed by the Filter Monitor. On x86 instead of calling CmRegisterCallback it additionally hooks about 60 functions of the Service Descriptor Table (which is a lot), but that’s no longer possible on x64.

So, let’s remove the filters and re-launch k-test. It works now.

Final disclaimer: It is not my intent to comment on security features of anti-viruses, I just wanted to present my new tool and show its functionalities. I was already familiar with the internals of Kaspersky before writing this utility.

I hope you enjoyed the presentation.”

P.S. A huge thanks goes to Alessandro Gario for providing me with all the different versions of ntoskrnl.exe.

Native Blocks Pre-Alpha

Here’s a presentation of my new tool. I called it Native Blocks. It’s a re-assembler basically. Since a written presentation would take me too much time I prepared a video presentation.

Again, this is a pre-alpha. This tool will soon support other technologies such as java, actionscript and maybe even x86. Right now it only supports .NET (and even .NET support will be hugely improved, like for instance supporting the direct modification of assemblies without having to use Rebel.NET).

The development of this tool depends mainly on the interest of people.

As I can be considered a student from now on, I would like to earn some extra money by writing tools such as this one. I have still my job as consultant, but it’s a very limited partime, because I just became a student.

This tool is in my opinion pretty good, it is not only good for deobfuscation purposes but also patching and assembling on the fly.

If this tool can be sold, then the support of technologies will depend on requests. I think I’ll add Java immediately and after that maybe x86/x64. Again it depends.

Suggestions and comments are welcome.

Kernel: 3rd edition

I don’t want to show too much, this is just a small preview. Yes, it’s running on Ubuntu and it runs on OSX just as well.
I don’t know if I’m going to ship a Linux and an OSX version apart from the Windows one, maybe not immediately. It also depends on the number of requests for it.

Some insights into the new kernel:

– The kernel is now stream based, this means it can read files, memory, disks etc.
– Complete multithread support.
– A CFFStream can be shared among CFFObjects even if they’re owned by a different thread.
– The same CFFObject can be shared among threads.
– Complete endianess support: every file format has a default endianess but can be loaded with a different one. For instance: it is possible to load a PE file with all fields in big endian.
– Support for all most common string encodings.
– Support for integer types of infinite size.
– Support for multiple file formats.
– Easily exposable to scripting languages.

There is more and an impressive amount of work has still to be done, although the kernel is about to be finished. I won’t tell all the new features of the GUI, because it’s way too soon.

Qt: Now LGPL

Nokia today announced that its Qt cross-platform user interface (UI) and application framework for desktop and embedded platforms will be available under the open source LGPL version 2.1 license from the release of Qt 4.5.

I’ve been waiting for such a decision by Nokia and yet it really came as a surprise. Making Qt free even for closed software will hugely increase their popularity. It will also allow me to develop some crossplatform freeware utilities. I’m still working at the kernel of the CFF Explorer in my free time, but once the kernel is finished it can be used to develop some nice stuff apart from the CFF Explorer itself.

This confirms what I wrote in the article about Qt internals and reversing. This framework will be used more and more in the future.

Kudos to the best framework of all time.