# BEDaisy

reverse engineering of bedaisy.sys (battleyes kernel driver). By registering on image load callbacks and IAT hooking BEDaisy's `MmGetSystemRoutineAddress` we can simply hook any imports
we want and have control flow over subsequent functions.

<img src="https://imgur.com/NFGyGrY.png"/>

# APCS

The below function will be executed in each thread that bedaisy registers an APC on.

```cpp
__int64 __usercall apc_callback@<rax>(char _CL@<cl>, char _BH@<bh>, __int64 *a3@<r9>)
{
  __int64 v4; // rbx

  __asm { rcl     bh, cl }
  v4 = *a3;
  *(_DWORD *)(v4 + 2160) = RtlWalkFrameChain(*a3 + 0x70, 256i64, 0i64);
  return KeSetEvent(v4 + 88, 0i64, 0i64);
}
```

Registeration of APCS:

```cpp
    current_thread_id = PsLookupThreadByThreadId(thread_id, &some_pethread);
    v17 = 0;
    if ( (int)current_thread_id >= 0 )
    {
      allocated_pool = ExAllocatePool(0x200i64, 0x878i64);
      allocated_pool_1 = allocated_pool;
      allocated_pool_2 = allocated_pool;
      if ( allocated_pool )
      {
        allocated_pool_plus_58 = allocated_pool + 0x58;
        KeInitializeEvent((PRKEVENT)(allocated_pool + 0x58), NotificationEvent, 0);
        __asm { rcl     cx, 0C6h }
        LOBYTE(v77) = 0;
        KeInitializeApc(allocated_pool_2, some_pethread, 0i64, j_apc_callback, 0i64, 0i64, v77, 0i64);
        if ( (unsigned __int8)KeInsertQueueApc(allocated_pool_2, allocated_pool_2, 0i64, 2i64) )
        ```