Mass campaign: Cross Site Scripting (XSS) attempt

 1name: "Mass campaign: Cross Site Scripting (XSS) attempt"
 2description: "Message subject or body contains Cross Site Scripting (XSS) indicators, and was sent to multiple unknown senders. Known spam technique."
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  and (
 8    length(recipients.to) > 10
 9    and length(filter(recipients.to,
10                      .email.domain.domain not in $org_domains
11                      and .email.email not in $recipient_emails
12                      and (
13                        .email.domain.valid
14                        or strings.icontains(.display_name, "undisclosed")
15                      )
16               )
17    ) >= 10
18  )
19  and (
20    strings.ilike(subject.subject,
21                  '*<*script*>*',
22                  '*xss.report*',
23                  '*eval(atob*',
24                  '*<*onload*>*',
25                  '*<*onerror*>*'
26    )
27    or strings.ilike(body.current_thread.text,
28                     '*<*script*>*',
29                     '*xss.report*',
30                     '*eval(atob*',
31                     '*<*onload*>*',
32                     '*<*onerror*>*'
33    )
34  )
35  and (
36    length(body.links) == 0
37    or (
38      length(body.links) == 1
39      and all(body.links, .href_url.domain.domain == "this.id")
40    )
41  )
42  and profile.by_sender().prevalence != "common"
43  and not profile.by_sender().solicited
44  and not profile.by_sender().any_false_positives
45  
46  // negate highly trusted sender domains unless they fail DMARC authentication
47  and (
48    (
49      sender.email.domain.root_domain in $high_trust_sender_root_domains
50      and (
51        any(distinct(headers.hops, .authentication_results.dmarc is not null),
52            strings.ilike(.authentication_results.dmarc, "*fail")
53        )
54      )
55    )
56    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
57  )
58    
59
60attack_types:
61  - "Malware/Ransomware"
62  - "Spam"
63tactics_and_techniques:
64  - "Exploit"
65  - "Free email provider"
66  - "Scripting"
67  - "Social engineering"
68detection_methods:
69  - "Content analysis"
70  - "Header analysis"
71  - "Sender analysis"
72id: "6cbb7124-2e84-50a5-a707-cc26683bb42a"