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").credphish.disposition == "phishing"
28          and ml.link_analysis(., mode="aggressive").credphish.confidence in (
29            "medium",
30            "high"
31          )
32          and not .href_url.domain.root_domain == "c3reservations.com"
33  )
34  and (
35    (
36      profile.by_sender().prevalence in ("new", "outlier")
37      and not profile.by_sender().solicited
38    )
39    or (
40      profile.by_sender().any_messages_malicious_or_spam
41      and not profile.by_sender().any_false_positives
42    )
43  )
44  
45  // negate docusign 'via' messages
46  and not (
47    any(headers.hops,
48        any(.fields,
49            .name == "X-Api-Host" and strings.ends_with(.value, "docusign.net")
50        )
51    )
52    and strings.contains(sender.display_name, "via")
53  )
54  
55  // negate docusign originated emails
56  and not any(headers.hops,
57              regex.imatch(.received.server.raw, ".+.docusign.(net|com)")
58  )
59  
60  // negate highly trusted sender domains unless they fail DMARC authentication
61  and (
62    (
63      sender.email.domain.root_domain in $high_trust_sender_root_domains
64      and not headers.auth_summary.dmarc.pass
65    )
66    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
67  )  
68
69attack_types:
70  - "Credential Phishing"
71tactics_and_techniques:
72  - "Social engineering"
73detection_methods:
74  - "Computer Vision"
75  - "Sender analysis"
76  - "URL analysis"
77  - "URL screenshot"
78id: "f0c95bb7-afeb-5c8d-a654-74b5e026007f"