Sublime Security low experimental mql

Inline image as message with attachment or link

Using inline images in lieu of HTML or text content in the message is a known technique used to bypass content based scanning engines. We've observed this technique used to deliver malware via attachments and phish credentials.

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Detection Logic

type.inbound
and length(body.html.raw) < 200
and length(body.links) > 0
and (
  // as of 20220116 there's a link parsing bug with .png inline images, so ignore those
  any(body.links, not strings.ilike(.href_url.url, "*.png"))

  // cid images are treated as attachments, so we're looking for more than 1
  or (
    length(attachments) > 1
    and any(attachments, .file_type not in $file_types_images)
  )
)
and strings.ilike(body.html.raw, "*img*cid*")
and (
  profile.by_sender().prevalence in ("new", "outlier")
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)

Field Validations

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