Detection rules › Sublime MQL

Link: Scribd fullscreen link from suspicious sender

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

Detects messages containing Scribd links with the fullscreen parameter from senders with no prior benign communication or recent history.

Threat classification

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

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesFree file host, Social engineering, Evasion

Event coverage

Rule body MQL

type.inbound
and length(body.links) < 10
and any(body.links,
        (
          .href_url.domain.root_domain == "scribd.com"
          or strings.icontains(.href_url.query_params, 'scribd.com')
          or strings.icontains(.href_url.query_params, 'scribd%2ecom')
          or strings.icontains(.href_url.query_params, 'scribd%252ecom')
        )
        and strings.icontains(.href_url.fragment, 'fullscreen')
)
and not profile.by_sender_email().any_messages_benign

Detection logic

Scope: inbound message.

Detects messages containing Scribd links with the fullscreen parameter from senders with no prior benign communication or recent history.

  1. inbound message
  2. length(body.links) < 10
  3. any of body.links where all hold:
    • any of:
      • .href_url.domain.root_domain is 'scribd.com'
      • .href_url.query_params contains 'scribd.com'
      • .href_url.query_params contains 'scribd%2ecom'
      • .href_url.query_params contains 'scribd%252ecom'
    • .href_url.fragment contains 'fullscreen'
  4. not:
    • profile.by_sender_email().any_messages_benign

Inspects: body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.fragment, body.links[].href_url.query_params, type.inbound. Sensors: profile.by_sender_email, strings.icontains.

Indicators matched (5)

FieldMatchValue
body.links[].href_url.domain.root_domainequalsscribd.com
strings.icontainssubstringscribd.com
strings.icontainssubstringscribd%2ecom
strings.icontainssubstringscribd%252ecom
strings.icontainssubstringfullscreen