huntrule

Citrix ADC Proxy Log Detection for CVE-2023-4966 Sensitive Info Disclosure Attempts via OIDC Endpoint

Alerts on successful GETs to /oauth/idp/.well-known/openid-configuration in Citrix ADC proxy logs consistent with CVE-2023-4966 probing.

FreeReviewedSigma · Medium · v5
Category
proxy
Author
Nasreddine Bencherchali (Nextron Systems), Michael Haag (STRT) (SigmaHQ), DRL 1.1
Published
2023-11-28
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule identifies potential exploitation attempts of CVE-2023-4966 against Citrix ADC / NetScaler Gateway by matching proxy log requests for the OpenID configuration path under an /oauth/idp/.well-known/openid-configuration URI. It looks specifically for HTTP GET requests that return a successful 200 status, which can indicate probing of OAuth/OIDC-related endpoints tied to the referenced disclosure issue. The detection relies on proxy telemetry fields including request method, URI substring match, and response status code.

Reporting behind it

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Citrix ADC Proxy Log Detection for CVE-2023-4966 Sensitive Info Disclosure Attempts via OIDC Endpoint
Pivot detection · T1190 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. 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.