Self-impersonation: Sender matches recipient with bolded name and suspicious link

 1name: "Self-impersonation: Sender matches recipient with bolded name and suspicious link"
 2description: "Detects messages where the sender's email address matches the recipient's email address, with the sender's display name appearing in bold text and a suspicious 'Read the Message' link present in the body."
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  // sender matches recipients
 8  and (
 9    length(recipients.to) == 1
10    and recipients.to[0].email.email == sender.email.email
11  )
12  // sender in current thread BOLD
13  and any(html.xpath(body.html, '//b').nodes,
14          .display_text == sender.display_name
15  )
16  // we want the dashed html element to contain a link, and that link to include part of the subject (the subject is the org)
17  and any(html.xpath(body.html,
18                     '//table//td[contains(@style, "border-style: dashed") and contains(@style, "border-width: 1pt")]//a[./b]'
19          ).nodes,
20          any(regex.extract(subject.base, '(?P<word>\w+)'),
21              any(..links,
22                  strings.icontains(.href_url.url, ..named_groups["word"])
23              )
24          )
25  )  
26attack_types:
27  - "Credential Phishing"
28tactics_and_techniques:
29  - "Evasion"
30  - "Social engineering"
31detection_methods:
32  - "Header analysis"
33  - "HTML analysis"
34  - "Sender analysis"
35id: "0129a805-2fe2-5a40-81bc-b3459085aa23"