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    strings.ilike(sender.display_name, '*american express*')
12    or strings.ilike(sender.display_name, "*amer?can expres*")
13    or strings.ilevenshtein(sender.display_name, 'american express') <= 2
14    or strings.ilike(sender.email.domain.domain, '*americanexpress*')
15  )
16  and sender.email.domain.root_domain not in (
17    'aexp.com',
18    'americanexpress.ae',
19    'americanexpress.com',
20    'americanexpress.co.uk',
21    'americanexpress.com.bh',
22    'aexpfeedback.com',
23    'amexnetwork.com',
24    'accountonline.com',
25    'transunion.com',
26    'amexgiftcard.com',
27    'amexgbt.com',
28    'herrickstravelamex.com',
29    'citi.com',
30    'secure.com'
31  )
32  and sender.email.domain.domain not in ('accountprotection.microsoft.com', 'amex.membershipmail.net')
33
34  and not profile.by_sender().solicited
35
36  // negate highly trusted sender domains unless they fail DMARC authentication
37  and (
38    (
39      sender.email.domain.root_domain in $high_trust_sender_root_domains
40      and not headers.auth_summary.dmarc.pass
41    )
42    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
43  )  
44
45attack_types:
46  - "Credential Phishing"
47tactics_and_techniques:
48  - "Impersonation: Brand"
49  - "Lookalike domain"
50  - "Social engineering"
51detection_methods:
52  - "Header analysis"
53  - "Sender analysis"
54id: "992a9fa9-84ee-5065-8486-b3a2a8ffa676"