Okta user.session.start via anonymising proxy service

Identifies Okta user session starts where the session is marked as using an anonymizing proxy.

FreeReviewedSigma · High · v4

Product: okta
Service: okta
Author: kelnage (SigmaHQ), DRL 1.1
Published: 2023-09-07
Updated: 2026-07-31

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies Okta events where a user session starts and the security context indicates the user is behind an anonymising proxy service. Attackers may use anonymising infrastructure to obscure the real source and complicate attribution during interactive access. It relies on Okta system log telemetry for user.session.start events and the securityContext.isProxy indicator.

Reporting behind it

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Okta user.session.start via anonymising proxy service

Pivot detection · T1685 · 9 related

Changelog

v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

okta-user-session-start-from-anonymizing-proxy-service-bde30855

title: Okta user.session.start via anonymising proxy service
id: 106a9fd2-5c2d-4b7b-bd5b-7a0c54d34896
status: test
description: This rule identifies Okta events where a user session starts and the security context indicates the user is behind an anonymising proxy service. Attackers may use anonymising infrastructure to obscure the real source and complicate attribution during interactive access. It relies on Okta system log telemetry for user.session.start events and the securityContext.isProxy indicator.
references:
  - https://developer.okta.com/docs/reference/api/system-log/
  - https://sec.okta.com/articles/2023/08/cross-tenant-impersonation-prevention-and-detection
  - https://github.com/SigmaHQ/sigma/blob/master/rules/identity/okta/okta_user_session_start_via_anonymised_proxy.yml
author: kelnage, Huntrule Team
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
license: DRL-1.1
related:
  - id: bde30855-5c53-4c18-ae90-1ff79ebc9578
    type: derived

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