sublimemediumRule

Attachment: ICS calendar file with legal language

Detects calendar files (.ics files) whose parsed event details reference legal or court-related themes such as settlements, subpoenas, litigation documents, or formal demands.

MITRE ATT&CK

T1566.002 T1534 T1656 T1566 T1598 T1036 T1027

initial-accessdefense-evasion

Detection Query

type.inbound
and any(attachments,
        (
          .file_type == "ics"
          or .file_extension == "ics"
          or .content_type in ("application/ics", "text/calendar")
        )
        //
        // This rule makes use of a beta feature and is subject to change without notice
        // using the beta feature in custom rules is not suggested until it has been formally released
        //
        and any(beta.file.parse_ics(.).events,
                (
                  any([.summary, .description],
                      regex.icontains(.,
                                      '(?:dear|hi|hello).(?:counsel|team),',
                                      'file attached',
                                      '\brefer\b',
                                      '\brespon(?:d|se)\b',
                                      '\breview\b'
                      )
                  )
                  or any(.links, regex.icontains(.display_text, 'view'))
                )
                and any([.summary, .description],
                        regex.icontains(.,
                                        'case resolution material',
                                        'court-related',
                                        'court.(?:subpoena|summons)',
                                        '(?:court case|litigation).(?:document|letter)',
                                        'formal.(?:dispute|mediation|recovery)',
                                        'proposed counteroffer',
                                        'paga settlement',
                                        'settlement.(?:&|and.)?(?:brief|document|finalization|material)',
                                        "view court order"
                        )
                )
        )
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Attachment: ICS calendar file with legal language"
description: "Detects calendar files (.ics files) whose parsed event details reference legal or court-related themes such as settlements, subpoenas, litigation documents, or formal demands."
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any(attachments,
          (
            .file_type == "ics"
            or .file_extension == "ics"
            or .content_type in ("application/ics", "text/calendar")
          )
          //
          // This rule makes use of a beta feature and is subject to change without notice
          // using the beta feature in custom rules is not suggested until it has been formally released
          //
          and any(beta.file.parse_ics(.).events,
                  (
                    any([.summary, .description],
                        regex.icontains(.,
                                        '(?:dear|hi|hello).(?:counsel|team),',
                                        'file attached',
                                        '\brefer\b',
                                        '\brespon(?:d|se)\b',
                                        '\breview\b'
                        )
                    )
                    or any(.links, regex.icontains(.display_text, 'view'))
                  )
                  and any([.summary, .description],
                          regex.icontains(.,
                                          'case resolution material',
                                          'court-related',
                                          'court.(?:subpoena|summons)',
                                          '(?:court case|litigation).(?:document|letter)',
                                          'formal.(?:dispute|mediation|recovery)',
                                          'proposed counteroffer',
                                          'paga settlement',
                                          'settlement.(?:&|and.)?(?:brief|document|finalization|material)',
                                          "view court order"
                          )
                  )
          )
  )
  
attack_types:
  - "BEC/Fraud"
tactics_and_techniques:
  - "Social engineering"
  - "Evasion"
  - "ICS Phishing"
detection_methods:
  - "File analysis"
  - "Content analysis"
  - "URL analysis"
id: "3c770c55-d143-5e01-a479-4f11c69cfd7a"