Credential phishing content and link (untrusted sender)

 1name: "Credential phishing content and link (untrusted sender)"
 2description: |
 3  Message contains credential theft language and a link to a credential phishing page from an unknown sender.
 4  We use Link Analysis in aggressive mode to increase our chances of scanning.  
 5type: "rule"
 6severity: "high"
 7source: |
 8  type.inbound
 9  and (
10    any(ml.nlu_classifier(body.current_thread.text).intents,
11        .name == "cred_theft" and .confidence in ("medium", "high")
12    )
13    // embedded in an image attachment
14    // note: don't use message_screenshot() for now
15    // because it's not limited to current_thread and may FP
16    or any(attachments,
17           .file_type in $file_types_images
18           and any(file.explode(.),
19                   any(ml.nlu_classifier(.scan.ocr.raw).intents,
20                       .name == "cred_theft" and .confidence in ("medium", "high")
21                   )
22           )
23    )
24  )
25  and any(body.links,
26          .href_url.domain.domain != "play.google.com"
27          and ml.link_analysis(., mode="aggressive").effective_url.domain.domain != "play.google.com"
28          and ml.link_analysis(., mode="aggressive").credphish.disposition == "phishing"
29          and ml.link_analysis(., mode="aggressive").credphish.confidence in (
30            "medium",
31            "high"
32          )
33          and not .href_url.domain.root_domain == "c3reservations.com"
34  )
35  and (
36    (
37      profile.by_sender().prevalence in ("new", "outlier")
38      and not profile.by_sender().solicited
39    )
40    or (
41      profile.by_sender().any_messages_malicious_or_spam
42      and not profile.by_sender().any_false_positives
43    )
44  )
45  
46  // negate docusign 'via' messages
47  and not (
48    any(headers.hops,
49        any(.fields,
50            .name == "X-Api-Host" and strings.ends_with(.value, "docusign.net")
51        )
52    )
53    and strings.contains(sender.display_name, "via")
54  )
55  
56  // negate docusign originated emails
57  and not any(headers.hops,
58              regex.imatch(.received.server.raw, ".+.docusign.(net|com)")
59  )
60  
61  // negate highly trusted sender domains unless they fail DMARC authentication
62  and (
63    (
64      sender.email.domain.root_domain in $high_trust_sender_root_domains
65      and not headers.auth_summary.dmarc.pass
66    )
67    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
68  )  
69
70attack_types:
71  - "Credential Phishing"
72tactics_and_techniques:
73  - "Social engineering"
74detection_methods:
75  - "Computer Vision"
76  - "Sender analysis"
77  - "URL analysis"
78  - "URL screenshot"
79id: "f0c95bb7-afeb-5c8d-a654-74b5e026007f"