diff --git a/detection-rules/body_self_sender_bold.yml b/detection-rules/body_self_sender_bold.yml new file mode 100644 index 00000000000..336bd5524ce --- /dev/null +++ b/detection-rules/body_self_sender_bold.yml @@ -0,0 +1,35 @@ +name: "Self-impersonation: Sender matches recipient with bolded name and suspicious link" +description: "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." +type: "rule" +severity: "medium" +source: | + type.inbound + // sender matches recipients + and ( + length(recipients.to) == 1 + and recipients.to[0].email.email == sender.email.email + ) + // sender in current thread BOLD + and any(html.xpath(body.html, '//b').nodes, + .display_text == sender.display_name + ) + // we want the dashed html element to contain a link, and that link to include part of the subject (the subject is the org) + and any(html.xpath(body.html, + '//table//td[contains(@style, "border-style: dashed") and contains(@style, "border-width: 1pt")]//a[./b]' + ).nodes, + any(regex.extract(subject.base, '(?P\w+)'), + any(..links, + strings.icontains(.href_url.url, ..named_groups["word"]) + ) + ) + ) +attack_types: + - "Credential Phishing" +tactics_and_techniques: + - "Evasion" + - "Social engineering" +detection_methods: + - "Header analysis" + - "HTML analysis" + - "Sender analysis" +id: "0129a805-2fe2-5a40-81bc-b3459085aa23"