Link: Romance/Sexual Language With Suspicious Link

Detects messages containing romantic or adult-themed language, combined with links to newly registered domains or suspicious reply-to addresses.

Sublime rule (View on GitHub)

 1name: "Link: Romance/Sexual Language With Suspicious Link"
 2description: "Detects messages containing romantic or adult-themed language, combined with links to newly registered domains or suspicious reply-to addresses."
 3type: "rule"
 4severity: "low"
 5source: |
 6  type.inbound
 7  and length(body.previous_threads) == 0
 8  and any(ml.nlu_classifier(body.current_thread.text).topics,
 9          .name in ("Romance", "Sexually Explicit Messages")
10          and .confidence == "high"
11  )
12  and 1 of (
13    any(body.links, network.whois(.href_url.domain).days_old < 30),
14    any(body.links, .href_url.domain.root_domain in $url_shorteners),
15    any(headers.reply_to, network.whois(.email.domain).days_old < 30)
16  )
17  and 0 < length(distinct(body.links,
18                          .href_url.domain.root_domain not in ("aka.ms")
19                 )
20  ) < 3
21  and all(body.links,
22          .href_url.domain.root_domain != sender.email.domain.root_domain
23  )  
24
25attack_types:
26  - "Spam"
27tactics_and_techniques:
28  - "Social engineering"
29detection_methods:
30  - "Content analysis"
31  - "Header analysis"
32  - "URL analysis"
33  - "Whois"
34id: "d5694cae-bee8-588e-8123-2c3e3459118b"
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