A small, on the fly video presentation of my new utility.
The emphasis of this application stands on parsing correctly the PDF format, if it can’t because the PDF is malformed (very common among malicious PDFs), then it provides the tools to read the objects nonetheless. I tested it on many PDF (also malicious ones) and it handles all of them very well.
As I have written this application in five days, there are still some small features I’d like to add, but most of the code is already there. I started the development of it quite some time ago on a weekend while I was sick at home and have found only now the time to finish it.
I have no plans about how and when to release it yet, but some friends of mine will start using it in real world scenarios.
P.S. Thanks to Alessandro Gario for the throughout testing.
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.
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.
I updated the scripting language of the old CFF Explorer which now provides a function to automatically create reports of .NET metadata tables. The function is called LogPrintStruct and is to be used along with the logging functions the scripting provides. Here’s a small script you can find in the “Scripts” directory of the CFF Explorer which creates a report of all .NET tables contained in an assembly:
-- this script generates a report of a PE's .NET metadata tables.
5.
ResolutionScope: A Name: 4D (Object)
Namespace: 3A (System)
6.
ResolutionScope: A Name: 54(ValueType)
Namespace: 3A (System)
etc.
I included this new feature because many developers asked me to. Reading the generated report files is much easier than manually reading the raw .NET format. The current scripting system won’t be implemented in the newer CFF Explorer, I only inserted this new feature because it will take me much more time to release the newer CFF Explorer.
Thanks to CodeRipper for signalling a corrupted .NET assembly which caused the CFF Explorer to crash when opening it. I improved the integrity checks.
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.
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.
I wanted to comment and add some thoughts about the IDA-on-IPhone news I read on woodmann.
Good news for real iPhone fans: we ported IDA to iPhone! It can handle any application and provides the same analysis as on other platforms. It is funny to see IDA on a such small device:
http://hexblog.com/2008/07/ida_on_iphone.html
Ilfak Guilfanov
It’s funny, because in theory the new CFF Explorer will be compilable for mac os (being written in Qt), thus also IPhone. The only problem is the small display of such devices and I’m not sure if there’s a possibility to reduce the needed space, but I’m quite optimistic.
I mention this because the new CFF Explorer will support elf and other formats (lib, object, symbian etc), making it useful also for other systems and it might become part of a new generation of cross platform/device tools. It would be encouraging to know that in the future it will be possible to do reversing stuff on such a small device. The new CFF will also have zoom in/out features for the hex editor, making it very useful on devices with a small (or big) display.
I hope that other programmers will follow the same lead.
The main problem is writing cross platform applications and reorganizing GUIs for small displays.
I want to share something I read on wikipedia some time ago:
Microsoft software is also presented as a “safe” choice for IT managers purchasing software systems. In an internal memo for senior management Microsoft’s head of C++ development, Aaron Contorer, stated:[7]
“The Windows API is so broad, so deep, and so functional that most Independent Software Vendors would be crazy not to use it. And it is so deeply embedded in the source code of many Windows apps that there is a huge switching cost to using a different operating system instead… It is this switching cost that has given the customers the patience to stick with Windows through all our mistakes, our buggy drivers, our high TCO (total cost of ownership), our lack of a sexy vision at times, and many other difficulties [...] Customers constantly evaluate other desktop platforms, [but] it would be so much work to move over that they hope we just improve Windows rather than force them to move. In short, without this exclusive franchise called the Windows API, we would have been dead a long time ago.
Companies such as Apple and Microsoft are very conscious of the strategic importance of hard binding applications to their propretary API. That’s why Apple pushes cocoa and Microsoft .NET. They don’t want cross platform development environments (oh and don’t tell me that .NET is cross-platform, before doing so, show me a .NET GUI with more than a button in it on a system which isn’t Windows), because it would make possible for users to switch to another system without losing his tools.
However, “the times they are a changin’”. Nowadays, developers are more conscious about this problem and prefer not to bind their application to only one platform. You can notice this if you pay attention to the names of newer applications. Ten years ago there were lots of windows applications which contained the word “win” in them. Winhex, WinDvd, Winzip, WinRar, WinAce, Winamp etc. etc. etc. Have you noticed that this trend has stopped? It’s interesting, right now a struggle between developers and OS producers is taking place. OS producers want to ever more bind (even more than before) developers to their platform. Why do I say more than before? Well, consider that .NET implements its own languages, you can’t simply share real C++ code with the managed one (yes, you can rely on pinvoke, but not for everything). Well, it’s a bit more complicate than that, I know, but unsafe code is not encouraged in the .NET environment. Meanwhile, Apple pushes Obj-C. I want to know how this ends. Speaking for myself, I refuse to take a side and will stick with my beloved C++ (the real one).
