Attachment: ICS calendar file with legal language

 1name: "Attachment: ICS calendar file with legal language"
 2description: "Detects calendar files (.ics files) whose parsed event details reference legal or court-related themes such as settlements, subpoenas, litigation documents, or formal demands."
 3type: "rule"
 4severity: "medium"
 5source: |
 6  type.inbound
 7  and any(attachments,
 8          (
 9            .file_type == "ics"
10            or .file_extension == "ics"
11            or .content_type in ("application/ics", "text/calendar")
12          )
13          //
14          // This rule makes use of a beta feature and is subject to change without notice
15          // using the beta feature in custom rules is not suggested until it has been formally released
16          //
17          and any(beta.file.parse_ics(.).events,
18                  (
19                    any([.summary, .description],
20                        regex.icontains(.,
21                                        '(?:dear|hi|hello).(?:counsel|team),',
22                                        'file attached',
23                                        '\brefer\b',
24                                        '\brespon(?:d|se)\b',
25                                        '\breview\b'
26                        )
27                    )
28                    or any(.links, regex.icontains(.display_text, 'view'))
29                  )
30                  and any([.summary, .description],
31                          regex.icontains(.,
32                                          'case resolution material',
33                                          'court-related',
34                                          'court.(?:subpoena|summons)',
35                                          '(?:court case|litigation).(?:document|letter)',
36                                          'formal.(?:dispute|mediation|recovery)',
37                                          'proposed counteroffer',
38                                          'paga settlement',
39                                          'settlement.(?:&|and.)?(?:brief|document|finalization|material)',
40                                          "view court order"
41                          )
42                  )
43          )
44  )
45    
46attack_types:
47  - "ICS Phishing"
48  - "BEC/Fraud"
49tactics_and_techniques:
50  - "Social engineering"
51  - "Evasion"
52detection_methods:
53  - "File analysis"
54  - "Content analysis"
55  - "URL analysis"
56id: "3c770c55-d143-5e01-a479-4f11c69cfd7a"