Detection rules › Sublime MQL

Attachment: Dropbox image lure with no Dropbox domains in links

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

Detects Dropbox phishing emails with no Dropbox links with image attachments from an untrusted sender.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesImpersonation: Brand, Social engineering

Event coverage

Rule body MQL

type.inbound
and length(filter(attachments, .file_type not in $file_types_images)) == 0
and any(body.links,
        not strings.ilike(.href_url.domain.root_domain, "dropbox.*")
)
and any(attachments,
        .file_type in $file_types_images
        and any(file.explode(.),
                strings.ilike(.scan.ocr.raw, "*dropbox*")
                and strings.ilike(.scan.ocr.raw, "*review*", "*sign*")
        )
)
and (
  not profile.by_sender().solicited
  or profile.by_sender().any_messages_malicious_or_spam
)
and not profile.by_sender().any_messages_benign 

Detection logic

Scope: inbound message.

Detects Dropbox phishing emails with no Dropbox links with image attachments from an untrusted sender.

  1. inbound message
  2. length(filter(attachments, .file_type not in $file_types_images)) is 0
  3. any of body.links where:
    • not:
      • .href_url.domain.root_domain matches 'dropbox.*'
  4. any of attachments where all hold:
    • .file_type in $file_types_images
    • any of file.explode(.) where all hold:
      • .scan.ocr.raw matches '*dropbox*'
      • .scan.ocr.raw matches any of 2 patterns
        • *review*
        • *sign*
  5. any of:
    • not:
      • profile.by_sender().solicited
    • profile.by_sender().any_messages_malicious_or_spam
  6. not:
    • profile.by_sender().any_messages_benign

Inspects: attachments[].file_type, body.links, body.links[].href_url.domain.root_domain, type.inbound. Sensors: file.explode, profile.by_sender, strings.ilike. Reference lists: $file_types_images.

Indicators matched (4)

FieldMatchValue
strings.ilikesubstringdropbox.*
strings.ilikesubstring*dropbox*
strings.ilikesubstring*review*
strings.ilikesubstring*sign*