Показаны сообщения с ярлыком afd. Показать все сообщения
Показаны сообщения с ярлыком afd. Показать все сообщения

вторник, 5 мая 2020 г.

afd endpoints owner

Alex and Yarden as usually made perfect work to bypass even paranoid EDRs
The main problem is detection of duplicated sockets. There is a hint however:
all ownership of the socket still belongs to the original creator – even when the creator exists (and actually, because Netio.sys is still referencing the original EPROCESS, the creator and the PID become “zombies” and leak resources).
o`k, reason is true, but reference holds by afd.sys. Lets see why
We need disasm 2 functions to write simple script. First - we need back offset from afd!AfdEndpointListHead to read endpoint. It can be extracted from AfdIsAddressInUse:
  mov     [rsp+arg_0], rbx
  mov     [rsp+arg_8], rbp
  mov     [rsp+arg_10], rsi
  push    rdi
  sub     rsp, 30h
  mov     rsi, rcx
  xor     ebx, ebx
  mov     rcx, cs:AfdGlobalData
  call    cs:__imp_ExEnterCriticalRegionAndAcquireResourceShared
  nop     dword ptr [rax+rax+00h]
  mov     rdi, cs:AfdEndpointListHead
  lea     rbp, AfdEndpointListHead
  jmp     short loc_1C003C0D3
; ---------------------------------------------------------------------------

loc_1C003C054:                          ; CODE XREF: AfdIsAddressInUse+BE
  lea     rdx, [rdi-120h]
...
loc_1C003C0D3
  cmp     rdi, rbp
  jnz     loc_1C003C054


Then we need offset to EPROCESS - it can be extracted for example from AfdFreeEndpointResources:

  mov     rcx, [rbx+28h]
  mov     edx, 200h
  call    cs:__imp_PsReturnPoolQuota
  nop     dword ptr [rax+rax+00h]
  mov     rcx, [rbx+28h]  ; Object
  call    cs:__imp_ObfDereferenceObject


Now we have all parts of this puzzle. Let`s see what we can do in windbg