• Sublime Core Feed
High Severity

Fake email quarantine notification

Labels

Credential Phishing
Social engineering
Content analysis
Natural Language Understanding
Sender analysis

Description

Detects phishing messages implying that emails have been delayed or blocked, prompting users to view, release, or delete pending messages.

References

No references.

Sublime Security
Created May 23rd, 2024 • Last updated Jul 16th, 2025
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and length(body.links) < 10
and (
  any(ml.nlu_classifier(body.current_thread.text).intents,
      .name == "cred_theft" and .confidence == "high"
  )
  or (
    length(body.current_thread.text) < 250
    and any(recipients.to,
            strings.icontains(body.current_thread.text, .email.domain.sld)
            or strings.icontains(body.current_thread.text, .email.local_part)
    )
  )
)
and 3 of (
  strings.ilike(body.current_thread.text, "*review*"),
  strings.ilike(body.current_thread.text, "*incoming*"),
  strings.ilike(body.current_thread.text, "*release*"),
  strings.ilike(body.current_thread.text, "*quarantine*"),
  strings.ilike(body.current_thread.text, "*messages*"),
  strings.ilike(body.current_thread.text, "*server error*"),
  strings.ilike(body.current_thread.text, "*blocked*"),
  strings.ilike(body.current_thread.text, "*prevented*"),
  strings.ilike(body.current_thread.text, "*validation*"),
  strings.ilike(body.current_thread.text, "*notification*"),
  strings.ilike(body.current_thread.text, "*kindly*"),
  strings.ilike(body.current_thread.text, "*on hold*"),
  strings.ilike(body.current_thread.text, "*held*"),
  strings.ilike(body.current_thread.text, "*pending*"),
  strings.like(body.current_thread.text, "* MX *")
)
and (
  any(body.links,
      regex.icontains(.display_text, "view", "release", "messages", "delete", "recover", "SSO")
  )
  or (
    length(body.links) < 3
    and any(body.links,
            any(recipients.to,
                .email.domain.root_domain == ..display_url.domain.root_domain
                and ..mismatched
            )
    )
  )
)
and not any(body.links,
            regex.icontains(.display_text,
                            "view document",
                            "review (&|and) sign document"
            )
)
and sender.email.domain.root_domain not in (
  "bing.com",
  "microsoft.com",
  "microsoftonline.com",
  "microsoftsupport.com",
  "microsoft365.com",
  "office.com",
  "office365.com",
  "onedrive.com",
  "sharepointonline.com",
  "yammer.com",
  "ppops.net"
)

// negate org domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $org_domains
    and (
      not headers.auth_summary.dmarc.pass
      // MS quarantine digest emails from an org domain are router "internally" to MS, therefore, there is no authentication information
      or not (
        headers.auth_summary.dmarc.pass is null
        and all(headers.domains,
                .root_domain in ("outlook.com", "office365.com")
        )
        // typical emails from freemail Outlook accounts are from prod.outlook.com
        and strings.ends_with(headers.message_id, "protection.outlook.com>")
      )
    )
  )
  or sender.email.domain.root_domain not in $org_domains
)

// 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
)
and not profile.by_sender().solicited
and not profile.by_sender().any_messages_benign
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