Detection rules › Sublime MQL

Service abuse: Mimecast URL with excessive path length

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

Detects messages containing the second stage Mimecast redirect URL with unusually long paths, potentially indicating abuse of the Mimecast URL redirection service to obfuscate malicious destinations.

Threat classification

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

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesEvasion, Open redirect

Event coverage

Rule body MQL

type.inbound
and any(filter(body.links,
               strings.icontains(.href_url.domain.root_domain, "mimecast")
               and strings.starts_with(.href_url.path, "/r/")
        ),
        length(.href_url.path) > 2000
)

Detection logic

Scope: inbound message.

Detects messages containing the second stage Mimecast redirect URL with unusually long paths, potentially indicating abuse of the Mimecast URL redirection service to obfuscate malicious destinations.

  1. inbound message
  2. any of filter(body.links) where:
    • length(.href_url.path) > 2000

Inspects: body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.path, type.inbound. Sensors: strings.icontains, strings.starts_with.

Indicators matched (2)

FieldMatchValue
strings.icontainssubstringmimecast
strings.starts_withprefix/r/