Detection rules › Sublime MQL

Subject and sender display name contains matching long alphanumeric string

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

Detects messages where both the subject line and sender display name contain identical alphanumeric strings that are between 32 and 64 characters, which may indicate automated generation or coordination between these fields for malicious purposes.

Threat classification

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

CategoryValues
Attack typesMalware/Ransomware, Credential Phishing
Tactics and techniquesEvasion, Social engineering

Event coverage

Message attribute
sender
subject
type

Rule body MQL

type.inbound
and any(regex.iextract(subject.subject,
                       '[^a-z0-9](?P<string>[a-z0-9]{32,64})(?:$|[^a-z0-9])'
        ),
        strings.contains(sender.display_name, .named_groups["string"])
)

Detection logic

Scope: inbound message.

Detects messages where both the subject line and sender display name contain identical alphanumeric strings that are between 32 and 64 characters, which may indicate automated generation or coordination between these fields for malicious purposes.

  1. inbound message
  2. any of regex.iextract(subject.subject) where:
    • strings.contains(sender.display_name)

Inspects: sender.display_name, subject.subject, type.inbound. Sensors: regex.iextract, strings.contains.

Indicators matched (1)

FieldMatchValue
regex.iextractregex[^a-z0-9](?P<string>[a-z0-9]{32,64})(?:$|[^a-z0-9])