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 (
16    (
17      sender.email.domain.root_domain in $high_trust_sender_root_domains
18      and not headers.auth_summary.dmarc.pass
19    )
20    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
21  )
22  and not profile.by_sender_email().any_messages_benign  
23tags:
24 - "Attack surface reduction"
25attack_types:
26  - "Credential Phishing"
27tactics_and_techniques:
28  - "Free file host"
29detection_methods:
30  - "Sender analysis"
31  - "URL analysis"
32  - "Header analysis"
33id: "cca7d2f5-421f-5421-ae13-da5588c15c8b"