VBS_dropper_script_Dec17_1

rule VBS_dropper_script_Dec17_1 {
   meta:
      description = "Detects a supicious VBS script that drops an executable"
      license = "Detection Rule License 1.1 https://github.com/Neo23x0/signature-base/blob/master/LICENSE"
      author = "Florian Roth (Nextron Systems)"
      reference = "Internal Research"
      date = "2018-01-01"
      score = 80
      id = "60f23d32-0737-501f-bf1c-1ca32af62efc"
   strings:
      $s1 = "TVpTAQEAAAAEAA" // 14 samples in goodware archive
      $s2 = "TVoAAAAAAAAAAA" // 26 samples in goodware archive
      $s3 = "TVqAAAEAAAAEAB" // 75 samples in goodware archive
      $s4 = "TVpQAAIAAAAEAA" // 168 samples in goodware archive
      $s5 = "TVqQAAMAAAAEAA" // 28,529 samples in goodware archive

      $a1 = "= CreateObject(\"Wscript.Shell\")" fullword ascii
   condition:
      filesize < 600KB and $a1 and 1 of ($s*)
}