Medium Severity

Link: Invalid reply-to with recipient details in subject, body, and encoded link

Description

Detects inbound messages with an invalid reply-to address where the recipient's domain SLD appears in the subject, the recipient's local part and domain SLD appear in the body, and the recipient's full email address is base64-encoded within a link fragment.

References

No references.

Sublime Security
Created Jul 16th, 2026 • Last updated Jul 16th, 2026
Source
type.inbound
// Invalid reply-to address
and any(headers.reply_to, not .email.domain.valid)
and strings.icontains(subject.base, recipients.to[0].email.domain.sld)
and strings.icontains(body.current_thread.text,
                      recipients.to[0].email.local_part
)
and strings.icontains(body.current_thread.text,
                      recipients.to[0].email.domain.sld
)
and any(body.current_thread.links,
        any(strings.scan_base64(.href_url.fragment),
            . == recipients.to[0].email.email
        )
)
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