Link: Flagged bit.ly link

Shortened link is blocked or gated by bit.ly. Indicator of malicious email.

Sublime rule (View on GitHub)

 1name: "Link: Flagged bit.ly link"
 2description: |
 3    Shortened link is blocked or gated by bit.ly. Indicator of malicious email.
 4type: "rule"
 5severity: "medium"
 6source: |
 7  type.inbound
 8  and any(body.links,
 9          // contains bit.ly link
10          .href_url.domain.root_domain == "bit.ly"
11          // link doesn't forward through
12          and beta.linkanalysis(.).effective_url.domain.domain == "bit.ly"
13          // blocked or gated by bit.ly
14          and strings.ilike(beta.linkanalysis(.).final_dom.display_text,
15                            "*link*blocked*",
16                            "*flagged*by*"
17          )
18  )
19
20  // negate highly trusted sender domains unless they fail DMARC authentication
21  and (
22    (
23      sender.email.domain.root_domain in $high_trust_sender_root_domains
24      and (
25        any(distinct(headers.hops, .authentication_results.dmarc is not null),
26            strings.ilike(.authentication_results.dmarc, "*fail")
27        )
28      )
29    )
30    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
31  )
32  and (
33    not profile.by_sender().solicited
34    or (
35      profile.by_sender().any_messages_malicious_or_spam
36      and not profile.by_sender().any_false_positives
37    )
38  )
39  and not profile.by_sender().any_false_positives  
40tags:
41  - "Attack surface reduction"
42attack_types:
43  - "Credential Phishing"
44tactics_and_techniques:
45  - "Evasion"
46detection_methods:
47  - "URL analysis"
48id: "1528eb6c-22fa-5879-b48c-53ee466fde23"

Related rules

to-top