Brand impersonation: Amazon Web Services (AWS)

 1name: "Brand impersonation: Amazon Web Services (AWS)"
 2description: "Detects messages impersonating AWS through similar display names combined with security-themed content and authentication failures. Excludes legitimate AWS communications and trusted senders."
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  and regex.icontains(strings.replace_confusables(sender.display_name),
 8                      '\baws\b|amazon web services|\bses\b'
 9  )
10  and (
11    // ML Topic Analysis and Credential Theft Detection
12    any(ml.nlu_classifier(body.current_thread.text).topics,
13        .name in ("Security and Authentication", "Secure Message")
14        and .confidence == "high"
15    )
16    or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).topics,
17           .name in ("Security and Authentication", "Secure Message")
18           and .confidence == "high"
19           and beta.ocr(file.message_screenshot()).text != ""
20    )
21    or any(ml.nlu_classifier(body.current_thread.text).intents,
22           .name == "cred_theft" and .confidence == "high"
23    )
24    or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
25           .name == "cred_theft" and .confidence == "high"
26    )
27  )
28  // Not from legitimate AWS domains
29  // there was a DMARC check here, but a lot of users send AWS notifications to groups/mailing lists that breaks DMARC
30  and not (
31    sender.email.domain.root_domain in $org_domains
32    or sender.email.domain.root_domain in (
33      "amazon.com",
34      "amazonaws.com",
35      "amazonses.com",
36      "awsevents.com",
37      "awsmp-seller-conference.com",
38      "aws-experience.com",
39      "marketplace.aws",
40      "aws.com",
41      "amazonaws.cn",
42      "repost.aws",
43      "awscustomercouncil.com",
44      "airtableemail.com", // used for re:Invent
45      "nmls.org", // "state examination system", realtor software
46      "mktgcampaigns.com", // Elastic + AWS co-marketing emails
47      "awseducate.com",
48      "awsacademy.com"
49    )
50    or sender.email.domain.tld == "local"
51  )
52  // negate highly trusted sender domains unless they fail DMARC authentication
53  and (
54    (
55      sender.email.domain.root_domain in $high_trust_sender_root_domains
56      and not headers.auth_summary.dmarc.pass
57    )
58    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
59  )
60  // sender email specific
61  and not (
62    profile.by_sender_email().solicited
63    // sender domain specific
64    or (
65      profile.by_sender().solicited
66      // 30 day decay
67      and (profile.by_sender().days_since.last_contact < 30)
68    )
69  )  
70
71attack_types:
72  - "Credential Phishing"
73tactics_and_techniques:
74  - "Impersonation: Brand"
75  - "Social engineering"
76detection_methods:
77  - "Content analysis"
78  - "Header analysis"
79  - "Optical Character Recognition"
80  - "Sender analysis"
81  - "Natural Language Understanding"
82id: "31de94e0-8c93-5408-929f-f448eea91830"