• Sublime Core Feed
Medium Severity

Business Email Compromise (BEC) attempt from untrusted sender

Labels

BEC/Fraud
Social engineering
Content analysis
Header analysis
Natural Language Understanding
Sender analysis

Description

Detects potential Business Email Compromise (BEC) attacks by analyzing text within the email body from first-time senders.

References

No references.

Sublime Security
Created Aug 17th, 2023 • Last updated Jun 24th, 2024
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(ml.nlu_classifier(body.current_thread.text).intents,
        .name in ("bec") and .confidence == "high"
)
// negating legit replies
and not (
  (
    strings.istarts_with(subject.subject, "RE:")
    // out of office auto-reply
    // the NLU model will handle these better natively soon
    or strings.istarts_with(subject.subject, "Automatic reply:")
    or regex.imatch(subject.subject, '(\[[^\]]+\]\s?){0,3}(re|fwd?|automat.*)\s?:.*')
  )
  and (
    length(headers.references) > 0
    or any(headers.hops, any(.fields, strings.ilike(.name, "In-Reply-To")))
  )
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_false_positives
  )
)

// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not headers.auth_summary.dmarc.pass
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)
MQL Rule Console
DocsLearning Labs

Playground

Test against your own EMLs or sample data.

Share

Post about this on your socials.

Get Started. Today.

Managed or self-managed. No MX changes.

Get Started