Okta User Session Start Via An Anonymising Proxy Service — Sigma Rule

Rule metadata and linked tags

Author: kelnage. Source status: test; severity: high. Source dates: 2023-09-07 / 2026-04-27.

{
  "product": "okta",
  "service": "okta"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a89e6a11460fcb2a023ff79bd7d9729282c7b1f5543b05f35d063c658e0ec6be

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Okta User Session Start Via An Anonymising Proxy Service
id: bde30855-5c53-4c18-ae90-1ff79ebc9578
status: test
description: Detects when an Okta user session starts where the user is behind an anonymising proxy service.
references:
    - https://developer.okta.com/docs/reference/api/system-log/
    - https://sec.okta.com/articles/2023/08/cross-tenant-impersonation-prevention-and-detection
author: kelnage
date: 2023-09-07
modified: 2026-04-27
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: okta
    service: okta
detection:
    selection:
        eventType: 'user.session.start'
        securityContext.isProxy: 'true'
    condition: selection
falsepositives:
    - If a user requires an anonymising proxy due to valid justifications.
level: high

Original YAML and metadata in JSON

False positives

• If a user requires an anonymising proxy due to valid justifications.

Source references

• https://developer.okta.com/docs/reference/api/system-log/
• https://sec.okta.com/articles/2023/08/cross-tenant-impersonation-prevention-and-detection