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Detection rules › Sublime MQL

Fake shipping notification with link to free file hosting

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

This rule detects spam emails impersonating FedEx, UPS, or USPS with links to free file hosting.

Threat classification

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

CategoryValues
Attack typesSpam
Tactics and techniquesFree file host, Impersonation: Brand, Social engineering

Event coverage

Message attribute
body
body.html
body.links (collection)
headers.return_path
sender.email
type

Rule body MQL

type.inbound
and length(attachments) == 0
and (
  regex.icontains(coalesce(body.html.inner_text, body.html.display_text),
                  '\bf[ _]?e[ _]?d[ _]?e[ _]?x\b'
  )
  and sender.email.domain.domain != "fedex.com"
  and headers.return_path.domain.domain != sender.email.domain.domain
  and any(body.links, strings.contains(.display_text, "track"))
  and length(body.links) < 10
)
and any(body.links,
        .href_url.domain.domain in $free_file_hosts
        or .href_url.domain.root_domain in $free_file_hosts
)
and (
  (
    sender.email.domain.root_domain in $free_email_providers
    and sender.email.email not in $sender_emails
  )
  or (
    sender.email.domain.root_domain not in $free_email_providers
    and sender.email.domain.root_domain not in $sender_domains
  )
  or sender.email.domain.valid == false
)

Detection logic

Scope: inbound message.

This rule detects spam emails impersonating FedEx, UPS, or USPS with links to free file hosting.

  1. inbound message
  2. length(attachments) is 0
  3. all of:
    • coalesce(body.html.inner_text, body.html.display_text) matches '\\bf[ _]?e[ _]?d[ _]?e[ _]?x\\b'
    • sender.email.domain.domain is not 'fedex.com'
    • headers.return_path.domain.domain is not sender.email.domain.domain
    • any of body.links where:
      • .display_text contains 'track'
    • length(body.links) < 10
  4. any of body.links where any holds:
    • .href_url.domain.domain in $free_file_hosts
    • .href_url.domain.root_domain in $free_file_hosts
  5. any of:
    • all of:
      • sender.email.domain.root_domain in $free_email_providers
      • sender.email.email not in $sender_emails
    • all of:
      • sender.email.domain.root_domain not in $free_email_providers
      • sender.email.domain.root_domain not in $sender_domains
    • sender.email.domain.valid is False

Inspects: body.html.display_text, body.html.inner_text, body.links, body.links[].display_text, body.links[].href_url.domain.domain, body.links[].href_url.domain.root_domain, headers.return_path.domain.domain, sender.email.domain.domain, sender.email.domain.root_domain, sender.email.domain.valid, sender.email.email, type.inbound. Sensors: regex.icontains, strings.contains. Reference lists: $free_email_providers, $free_file_hosts, $sender_domains, $sender_emails.

Indicators matched (2)

FieldMatchValue
regex.icontainsregex\bf[ _]?e[ _]?d[ _]?e[ _]?x\b
strings.containssubstringtrack