Open redirect: Signature Travel Network

 1name: "Open redirect: Signature Travel Network"
 2description: "Message contains use of the Signature Travel Network open redirect, but the sender is not Signature Travel Network. This has been exploited in the wild."
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  and any(body.links,
 8          .href_url.domain.root_domain == 'sigtn.com'
 9          and strings.iends_with(.href_url.path, "emt.cfm")
10          and strings.icontains(.href_url.query_params, "link=")
11  )
12  and sender.email.domain.root_domain not in (
13    'signaturetravelnetwork.com',
14    'sigtn.com'
15  )
16  and not any(headers.domains, .root_domain == "signaturetravelnetwork.com")
17  
18  // negate highly trusted sender domains unless they fail DMARC authentication
19  and (
20    (
21      sender.email.domain.root_domain in $high_trust_sender_root_domains
22      and not headers.auth_summary.dmarc.pass
23    )
24    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
25  )  
26attack_types:
27  - "Credential Phishing"
28tactics_and_techniques:
29  - "Open redirect"
30detection_methods:
31  - "Sender analysis"
32  - "URL analysis"
33id: "c92e3202-4dae-52ce-b9bd-2d7722c8e72d"