Brand impersonation: DocSend

 1name: "Brand impersonation: DocSend"
 2description: |
 3    Attack impersonating DocSend.
 4references:
 5  - "https://docsend.com"
 6type: "rule"
 7severity: "high"
 8source: |
 9  type.inbound
10  and (
11    (
12      sender.display_name =~ 'DocSend'
13      or strings.ilevenshtein(sender.display_name, 'DocSend') <= 1
14      or strings.icontains(sender.email.domain.domain, '*docsend*')
15      or regex.icontains(body.current_thread.text, 'on Dropbox\s*(?:Doc)?\s*Send')
16      or regex.icontains(body.current_thread.text,
17                         'The Dropbox\s*(?:Doc)?\s*Send Team'
18      )
19      or regex.icontains(body.current_thread.text,
20                         'Report to Dropbox\s*(?:Doc)?\s*Send'
21      )
22      or regex.icontains(body.current_thread.text,
23                         '©\s*20[0-9]{2}\s*,\s*Dropbox DocSend'
24      )
25      or any(ml.nlu_classifier(body.current_thread.text).entities,
26             .name in ("sender", "org")
27             and strings.icontains(.text, 'Dropbox DocSend')
28      )
29    )
30  )
31  and not (
32    sender.email.domain.root_domain in~ ('docsend.com')
33    and coalesce(headers.auth_summary.dmarc.pass, false)
34  )
35  and not profile.by_sender_email().solicited
36  
37  // negate highly trusted sender domains unless they fail DMARC authentication
38  and (
39    (
40      sender.email.domain.root_domain in $high_trust_sender_root_domains
41      and not headers.auth_summary.dmarc.pass
42    )
43    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
44  )  
45
46attack_types:
47  - "Credential Phishing"
48tactics_and_techniques:
49  - "Impersonation: Brand"
50  - "Lookalike domain"
51  - "Social engineering"
52detection_methods:
53  - "Header analysis"
54  - "Sender analysis"
55id: "cd9a3f7a-bda2-5cf9-9a0f-8acef23711a3"