SUSP_VBA_FileSystem_Access

rule SUSP_VBA_FileSystem_Access {
   meta:
      description = "Detects suspicious VBA that writes to disk and is activated on document open"
      author = "Florian Roth (Nextron Systems)"
      reference = "Internal Research"
      date = "2019-06-21"
      score = 60
      hash1 = "52262bb315fa55b7441a04966e176b0e26b7071376797e35c80aa60696b6d6fc"
      id = "91241b91-ca3f-5817-bf78-550fe015b467"
   strings:
      $s1 = "\\Common Files\\Microsoft Shared\\" wide
      $s2 = "Scripting.FileSystemObject" ascii

      $a1 = "Document_Open" ascii
      $a2 = "WScript.Shell" ascii
      $a3 = "AutoOpen" fullword ascii
   condition:
      uint16(0) == 0xcfd0 and filesize < 100KB and all of ($s*) and 1 of ($a*)
}