Learning about Windows rootkits lately, so here is my own implementation of some techniques. For an overview, see Features below.
I am just learning about kernel driver development, so this is for educational purposes mainly.
http://phrack.org/issues/55/5.html
You can integrate Banshee into your tooling, by including the Banshee.hpp file in your project, e.g.:
Banshee banshee = Banshee();
banshee.Install(driverPath);
banshee.Initialize();
int targetPid = GetDefenderPID(); // this would be your implementation
banshee.IoCtlKillProcess(targetPid); // instruct banshee to kill the targetprocessAn example implementation of all the features in a command line client is found in ./BansheeClient/BansheeClient.cpp:
Get in everyone, we're going to Kernel Land!
ZwTerminateProcess is simply called from kernel land to terminate any process. Additionally, you can bury a process to avoid it to restart by setting a kernel callback to process creation: If the target process is created, Banshee will set the CreationStatus of the target process to STATUS_ACCESS_DENIED.
E.g. to block defender, run bury with msmpeng, then kill <defender pid> and it won't come back anymore, since all process creation events with msmpeng in the image full path will be blocked.
This is done by modifying the EPROCESS structure, which is an kernel object that describes a processes attributes. It also holds a value that specifies the protection level of the process.
We can directly modify this value (aka Direct Kernel Object Modification or DKOM), since we are operating in Ring 0.
EPROCESS also holds a pointer to the current access token, so we can just make it point to e.g. the token of process 4 (SYSTEM) to elevate any process to SYSTEM.
For now, only Process- and Thread-Creation kernel callbacks are enumerated, by parsing the PsSetCreateNotifyProcess/ThreadRoutine routine to reach the private Psp* routine and then parsing the address of the array, where kernel callbacks are stored. With erase, callbacks can be erased by overwriting the function pointer to point to an empty function in Banshee instead.
By hooking the NTFS filesystem's IRP_MJ_CREATE handler, we can block any process from opening a handle to our driver file (This will probably change to a filter driver concept soon).
Using the undocumented gafAsyncKeyState function we can parse keystrokes from a session without using any API calls besides reading memory (https://www.unknowncheats.me/forum/c-and-c-/327461-kernel-mode-key-input.html).
These should only be used with a patchguard bypass or in a lab environment as they trigger BSOD.
Again, EPROCESS comes to help here - it contains a LIST_ENTRY of a doubly linked list called ActiveProcessLink which is queried by Windows to enumerate running processes. If we simply unlink an entry here, we can hide our process from tools like Process Monitor or Task Manager.
- This can cause Bluescreens, e.g. when the process is closed while being hidden or due to patchguard scanning the kernel memory. While the former can be fixed by not being so lazy when programming, the latter can not be as easily bypassed from within the driver.
You need to enable testsigning to load the driver. I also recommend to enable debugging for the kernel.
Run the following from an administrative prompt and reboot afterwards:
bcdedit /set testsigning on
bcdedit /debug onAfterwards you can run the client, after compiling the solution, with e.g.:
.\x64\Debug\BansheeClient.exe .\x64\Debug\Banshee.sysRun this in a VM, debug this VM with WinDbg and create a snapshot before. You will probably Bluescreen a lot when developing.
- reflectively loading the driver and cleaning mmunloaded/piddbcache afterwards
- dont use ioctls but shared memory instead
- enumerating more kernel callbacks
- clean up code... neverending story. e.g. a proper sig scanning engine
Maybe
- ETW provider disabling à la https://securityintelligence.com/posts/direct-kernel-object-manipulation-attacks-etw-providers/
- IRP hook
tcpip.systo hide network connections - tamper with telemetry (maybe via windivert?)
- remove threads from PspCidTable: https://www.unknowncheats.me/forum/anti-cheat-bypass/455676-remove-systemthread-pspcidtable.html
- MSR hooking à la https://www.cyberark.com/resources/threat-research-blog/fantastic-rootkits-and-where-to-find-them-part-1
- Backdoor authentication as described in the phrack article linked above
- Hiding only on special ocassion, e.g. on opening of task manager, to avoid patchguard crashes
- Shellcode injection from kernel land
- Registry key protection
- UnknownCheats which is literally the best resource for kernel driver / rootkit stuff
- Some offset code from and feature inspiration (please check out, great project): https://github.com/Idov31/Nidhogg
- Great introduction to drivers: https://www.codeproject.com/articles/9504/driver-development-part-1-introduction-to-drivers
- Great overview of techniques: https://www.cyberark.com/resources/threat-research-blog/fantastic-rootkits-and-where-to-find-them-part-1
- WinDbg and the Windows Internals book for helping me (kinda) understand what I am doing here lol
- Windows Kernel Programming by Pavel Yosifovich. Great book that I should have read before starting this
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