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Create headers_x_source_auth_sender_mismatch.yml #4497

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a65a81b
Create headers_x_source_auth_sender_mismatch.yml
D-Bolton May 15, 2026
1646a6d
Auto-format MQL and add rule IDs
May 15, 2026
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26 changes: 26 additions & 0 deletions detection-rules/headers_x_source_auth_sender_mismatch.yml
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Original file line number Diff line number Diff line change
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name: "Headers: X-Source-Auth mismatch with sender address"
description: "Detects messages where the X-Source-Auth header contains a different email address than the sender, indicating potential spoofing or mismatched authentication."
type: "rule"
severity: "medium"
source: |
type.inbound
// X-Source-Auth doesn't match sender
and any(headers.hops,
any(.fields,
.name == 'X-Source-Auth'
and .value != sender.email.email
and strings.parse_email(.value).email is not null
)
)
tags:
- "Attack surface reduction"
attack_types:
- "BEC/Fraud"
- "Credential Phishing"
tactics_and_techniques:
- "Spoofing"
- "Evasion"
detection_methods:
- "Header analysis"
- "Sender analysis"
id: "7756bf2c-4ef4-5112-8109-5f91b085171f"
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