суббота, 18 апреля 2020 г.

PsKernelRangeList on arm64 kernel

can be found using the same old trick
Sure constants are now different, so now KUSER_SHARED_DATA.SystemCall is 0xFFFFF78000000308 and KUSER_SHARED_DATA.ProcessorFeatures is 0xFFFFF78000000274

Commited today simple logic to find and parse it in my armpatched

пятница, 17 апреля 2020 г.

IDA Pro plugin for arm64 switch tables processing

IDA Pro supports arm64 very poorly - it also cannot parse switch tables. Let`s see how they looks on arm64 - for example in function NtQueryInformationThread:
 CMP             W1, #0x2D           ; check index
 B.HI            loc_140673294
 ADR             X9, dword_14066E9EC ; switch tab address
 LDRSW           X8, [X9,W1,UXTW#2]  ; index in W1 << 2
 ADR             X9, loc_14066E358   ; base address
 ADD             X8, X9, X8,LSL#2    ; base address + offset << 2
 BR              X8

What happens here? first "ADR x9, addr" loads address of switch table
Next LDRSW is like "mov x8, [x9 + 4 * w1]" on Intel - load DWORD at x9 + index w1 left shifted by 2
Then second ADR loads address of base for this switch table
ADD x8, x9, x8 << 2 sets in x8 address of actual jumps
and finally BR go to this address

So I just wrote quick and dirty plugin arm64sw.p64 based on armpatched for switch tables processing

четверг, 16 апреля 2020 г.

воскресенье, 12 апреля 2020 г.

bug in ida pro arm64 module

Lets see in ida pro some arm64 windows kernel, for example good old function PspSetCreateThreadNotifyRoutine:
 ADRP            X8, #PspNotifyEnableMask@PAGE
 ADD             X11, X8, #PspNotifyEnableMask@PAGEOFF
 TBNZ            W20, #0, loc_140690960
 ADD             X10, X11, #0x33C


register x11 contains address of PspNotifyEnableMask - in my case this is 0x1408AE6B0 and then x10 loading address of PspNotifyEnableMask + 0x33c = 0x1408AE9EC - this is actually PspCreateThreadNotifyRoutineCount. And no - you cannot fix last instruction with pressing O or Ctrl + O
Given that cross-refs in arm64 is highly dependent from correct code analysis - this is very annoing
Tested in ida pro 6.9 and 7.2

четверг, 9 апреля 2020 г.

armpatched

Several days ago I started my new pet project on GitHub, bcs
  • quarantine is boring
  • reading a book "ARM 64-Bit Assembly Language" without practice is useless
So I just forked arm64 disasm called armadillo, ported it on windows, added naïve pe loader (btw attempt to use MapViewOfFile function was unsuccessful with GetLastError 1132) and today add some practical usage of static code analysis to extract lists and lock of lookaside lists from arm64 windows kernel

Main magic happens in ntoskrnl_hack::find_lock_list function

воскресенье, 5 апреля 2020 г.

static code analysis

This cool article is good case to show how you can employ static code analysis for extracting some unexported symbols from binary code - in this case we need ExNPagedLookasideLock & ExNPagedLookasideListHead

Sure the first thing you need is disassembler. If you search at GitHub "x86 disasm" you will get something about 20 repositories, but we need one that satisfies some requirements:
  • disasm to some intermediate code and not in string output
  • can be used in kernel mode (just in case if you want to do it) which means that it must be written in C

So just choose the one with the most comprehensible code - bcs they all contains bugs and you anyway will fix them and/or add missed instructions

Lets start with exported function ExInitializeNPagedLookasideList. Simplest cases - xp 64bit:

четверг, 2 апреля 2020 г.

VfDifThunks

It seems that in w10 build 19569 new verifier table has appeared - VfDifThunks along with new exported function DifRegisterPlugin (which is used only in VerifierExt.sys for now). List of intercepted functions: