CobaltStrike_Resources_Beacon_Dll_v1_45

rule CobaltStrike_Resources_Beacon_Dll_v1_45
{
  meta:
    description = "Cobalt Strike's resources/beacon.dll Version 1.45"
    hash = "1a92b2024320f581232f2ba1e9a11bef082d5e9723429b3e4febb149458d1bb1"
		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 = "04d4d0ee-f1ee-5888-8108-ca55243c770a"
  strings:
    /*
      51        push    ecx
      0F B7 D2  movzx   edx, dx
      4A        dec     edx; switch 9 cases
      53        push    ebx
      56        push    esi
      83 FA 08  cmp     edx, 8
      77 6B     ja      short def_1000106C; jumptable 1000106C default case
      FF 24 ??  jmp     ds:jpt_1000106C[edx*4]; switch jump
    */
    $version_sig = { 51 0F B7 D2 4A 53 56 83 FA 08 77 6B FF 24 }

    /*
      B1 69          mov     cl, 69h ; 'i'
      30 88 [4]      xor     byte ptr word_10019F20[eax], cl
      40             inc     eax
      3D 28 01 00 00 cmp     eax, 128h
      7C F2          jl      short loc_10002664
    */
    $decode = { B1 ?? 30 88 [4] 40 3D 28 01 00 00 7C F2 }
  
  condition:
    all of them
}