Elastic low stable eql

Executable File with Unusual Extension

Identifies the creation or modification of an executable file with an unexpected file extension. Attackers may attempt to evade detection by masquerading files using the file extension values used by image, audio, or document file types.

View Source

Detection Logic

file where host.os.type == "windows" and event.action != "deletion" and

 /* MZ header or its common base64 equivalent TVqQ */
 file.Ext.header_bytes : ("4d5a*", "54567151*") and

 (
   /* common image file extensions */
   file.extension : ("jpg", "jpeg", "emf", "tiff", "gif", "png", "bmp", "fpx", "eps", "svg", "inf") or

   /* common audio and video file extensions */
   file.extension : ("mp3", "wav", "avi", "mpeg", "flv", "wma", "wmv", "mov", "mp4", "3gp") or

   /* common document file extensions */
   file.extension : ("txt", "pdf", "doc", "docx", "rtf", "ppt", "pptx", "xls", "xlsx", "hwp", "html")
  ) and
  not process.pid == 4 and
  not process.executable : "?:\\Program Files (x86)\\Trend Micro\\Client Server Security Agent\\Ntrtscan.exe"

Field Validations

Loading…

Comments (0)

Loading comments...