Link: Direct link to riddle.com hosted showcase

 1name: "Link: Direct link to riddle.com hosted showcase"
 2description: "Message contains a single link to a Riddle.com hosted showcase which has been observed abused for credential phishing landing"
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  and length(body.links) < 20
 8  and any(body.links, .href_url.domain.root_domain == "riddle.com")
 9  and length(filter(body.links,
10                    .href_url.domain.root_domain == "riddle.com"
11                    and strings.istarts_with(.href_url.path, '/view/')
12             )
13  ) == 1
14  // negate highly trusted sender domains unless they fail DMARC authentication
15  and not (
16    sender.email.domain.root_domain in $high_trust_sender_root_domains
17    and coalesce(headers.auth_summary.dmarc.pass, false)
18  )
19  and not profile.by_sender_email().any_messages_benign  
20tags:
21 - "Attack surface reduction"
22attack_types:
23  - "Credential Phishing"
24tactics_and_techniques:
25  - "Free file host"
26detection_methods:
27  - "Sender analysis"
28  - "URL analysis"
29  - "Header analysis"
30id: "cca7d2f5-421f-5421-ae13-da5588c15c8b"