CobaltStrike_Resources_Beacon_x64_v3_5_hf1_and_v3_5_1

rule CobaltStrike_Resources_Beacon_x64_v3_5_hf1_and_v3_5_1
{
  meta:
    description = "Cobalt Strike's sleeve/beacon.x64.dll Versions 3.5-hf1 and 3.5.1"
    hash =  "934134ab0ee65ec76ae98a9bb9ad0e9571d80f4bf1eb3491d58bacf06d42dc8d"
		author = "gssincla@google.com"
		reference = "https://cloud.google.com/blog/products/identity-security/making-cobalt-strike-harder-for-threat-actors-to-abuse"
		date = "2022-11-18"
    
    id = "0c0e87d3-e0e2-5ddc-9d89-5e56443da4b8"
  strings:
    /*
      8B D3             mov     edx, ebx
      48 8B CF          mov     rcx, rdi
      E8 38 70 00 00    call    sub_180014548
      E9 FD FA FF FF    jmp     loc_18000D012
      41 B8 01 00 00 00 mov     r8d, 1
      8B D3             mov     edx, ebx
      48 8B CF          mov     rcx, rdi
      E8 3F 4D 00 00    call    sub_180012264
      48 8B 5C 24 30    mov     rbx, [rsp+28h+arg_0]
      48 83 C4 20       add     rsp, 20h
      5F                pop     rdi
    */

    $version_sig = { 8B D3 48 8B CF E8 38 70 00 00 E9 FD FA FF FF 
                     41 B8 01 00 00 00 8B D3 48 8B CF E8 3F 4D 00 00 
                     48 8B 5C 24 30 48 83 C4 20 5F }

    /*
      80 34 28 ??       xor     byte ptr [rax+rbp], 69h
      48 FF C0          inc     rax
      48 3D 00 10 00 00 cmp     rax, 1000h
      7C F1             jl      short loc_180016B3E
    */

    $decoder = { 80 34 28 ?? 48 FF C0 48 3D 00 10 00 00 7C F1 }
    
  condition:
    all of them
}