CobaltStrike_Resources_Beacon_Dll_v1_48

rule CobaltStrike_Resources_Beacon_Dll_v1_48
{
  meta:
    description = "Cobalt Strike's resources/beacon.dll Version 1.48"
    hash = "dd4e445572cd5e32d7e9cc121e8de337e6f19ff07547e3f2c6b7fce7eafd15e4"
		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 = "dd15099f-ad19-58df-9ed4-ce66d7ee8540"
  strings:
    /*
      48        dec     eax; switch 24 cases
      57        push    edi
      8B F1     mov     esi, ecx
      8B DA     mov     ebx, edx
      83 F8 17  cmp     eax, 17h
      77 12     ja      short def_1000115D; jumptable 1000115D default case, case 8
      FF 24 ??  jmp     ds:jpt_1000115D[eax*4]; switch jump
    */
    $version_sig = { 48 57 8B F1 8B DA 83 F8 17 77 12 FF 24 }
    
    /*
      B1 69          mov     cl, 69h ; 'i'
      30 88 [4]      xor     byte ptr word_1001F048[eax], cl
      40             inc     eax
      3D A8 01 00 00 cmp     eax, 1A8h
      7C F2          jl      short loc_100047B4
    */
    $decode = { B1 ?? 30 88 [4] 40 3D A8 01 00 00 7C F2 }
  
  condition:
    all of them
}