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          ml.link_analysis(., mode="aggressive").credphish.disposition == "phishing"
27          and ml.link_analysis(., mode="aggressive").credphish.confidence in (
28            "medium",
29            "high"
30          )
31          and not .href_url.domain.root_domain == "c3reservations.com"
32  )
33  and (
34    (
35      profile.by_sender().prevalence in ("new", "outlier")
36      and not profile.by_sender().solicited
37    )
38    or (
39      profile.by_sender().any_messages_malicious_or_spam
40      and not profile.by_sender().any_false_positives
41    )
42  )
43  
44  // negate docusign 'via' messages
45  and not (
46    any(headers.hops,
47        any(.fields,
48            .name == "X-Api-Host" and strings.ends_with(.value, "docusign.net")
49        )
50    )
51    and strings.contains(sender.display_name, "via")
52  )
53  
54  // negate docusign originated emails
55  and not any(headers.hops,
56              regex.imatch(.received.server.raw, ".+.docusign.(net|com)")
57  )
58  
59  // negate highly trusted sender domains unless they fail DMARC authentication
60  and (
61    (
62      sender.email.domain.root_domain in $high_trust_sender_root_domains
63      and not headers.auth_summary.dmarc.pass
64    )
65    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
66  )  
67
68attack_types:
69  - "Credential Phishing"
70tactics_and_techniques:
71  - "Social engineering"
72detection_methods:
73  - "Computer Vision"
74  - "Sender analysis"
75  - "URL analysis"
76  - "URL screenshot"
77id: "f0c95bb7-afeb-5c8d-a654-74b5e026007f"