Detection rules › Sublime MQL

Sender name contains Active Directory distinguished name

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

Sender's display name contains an Active Directory distinguished name or a similar string. This has been observed as a malicious indicator in the wild.

Threat classification

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

CategoryValues
Attack typesCredential Phishing

Event coverage

Rule body MQL

type.inbound
and (
  regex.icontains(sender.display_name, '\b(EX|LABS|OU|CN|EXCHANGE)(=|/)')
  or strings.icontains(sender.display_name, "/O=EXCHANGELABS")
)
and sender.email.domain.root_domain not in $org_domains
and not (
  sender.email.domain.root_domain in ('fnfcorp.com')
  and headers.auth_summary.dmarc.pass
)

Detection logic

Scope: inbound message.

Sender's display name contains an Active Directory distinguished name or a similar string. This has been observed as a malicious indicator in the wild.

  1. inbound message
  2. any of:
    • sender.display_name matches '\\b(EX|LABS|OU|CN|EXCHANGE)(=|/)'
    • sender.display_name contains '/O=EXCHANGELABS'
  3. sender.email.domain.root_domain not in $org_domains
  4. not:
    • all of:
      • sender.email.domain.root_domain in ('fnfcorp.com')
      • headers.auth_summary.dmarc.pass

Inspects: headers.auth_summary.dmarc.pass, sender.display_name, sender.email.domain.root_domain, type.inbound. Sensors: regex.icontains, strings.icontains. Reference lists: $org_domains.

Indicators matched (3)

FieldMatchValue
regex.icontainsregex\b(EX|LABS|OU|CN|EXCHANGE)(=|/)
strings.icontainssubstring/O=EXCHANGELABS
sender.email.domain.root_domainmemberfnfcorp.com