Brand impersonation: American Express (AMEX)

 1name: "Brand impersonation: American Express (AMEX)"
 2description: |
 3    Impersonation of the credit card provider American Express.
 4references:
 5  - "https://www.inc.com/joseph-steinberg/american-express-users-beware-this-scam.html"
 6type: "rule"
 7severity: "low"
 8source: |
 9  type.inbound
10  and (
11    regex.icontains(strings.replace_confusables(sender.display_name),
12                    'american ?express'
13    )
14    or strings.ilike(sender.display_name, "*amer?can expres*")
15    or strings.ilevenshtein(sender.display_name, 'american express') <= 2
16    or strings.icontains(body.current_thread.text,
17                         'american express customer service'
18    )
19    or strings.ilike(sender.email.domain.domain, '*americanexpress*')
20    or regex.imatch(sender.email.local_part, '.*americanexpress(?:\.com)?')
21    or (
22      strings.istarts_with(body.current_thread.text, 'american express')
23      and any(ml.nlu_classifier(body.current_thread.text).intents,
24              .name == "cred_theft" and .confidence != "low"
25      )
26    )
27  )
28  and sender.email.domain.root_domain not in (
29    'aexp.com',
30    'americanexpress.ae',
31    'americanexpress.com',
32    'americanexpress.co.uk',
33    'americanexpress.com.bh',
34    'aexpfeedback.com',
35    'amexnetwork.com',
36    'accountonline.com',
37    'transunion.com',
38    'amexgiftcard.com',
39    'amexgbt.com',
40    'herrickstravelamex.com',
41    'citi.com',
42    'secure.com',
43    'nectar.com',
44    'accentinfomedia.com',
45    'egencia.com',
46    'cardbenefitsadministration.com',
47    'nationstrust.com'
48  )
49  and sender.email.domain.domain not in (
50    'accountprotection.microsoft.com',
51    'amex.membershipmail.net'
52  )
53  and not profile.by_sender().solicited
54  
55  // negate highly trusted sender domains unless they fail DMARC authentication
56  and not (
57    sender.email.domain.root_domain in $high_trust_sender_root_domains
58    and coalesce(headers.auth_summary.dmarc.pass, false)
59  )  
60attack_types:
61  - "Credential Phishing"
62tactics_and_techniques:
63  - "Impersonation: Brand"
64  - "Lookalike domain"
65  - "Social engineering"
66detection_methods:
67  - "Header analysis"
68  - "Sender analysis"
69id: "992a9fa9-84ee-5065-8486-b3a2a8ffa676"