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

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
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

v5
Candidate ingested via manual entry.2026-07-31
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.

citrix-adc-proxy-logs-cve-2023-4966-sensitive-info-disclosure-probe-via-oidc-con-ff349b81

title: Citrix ADC Proxy Log Detection for CVE-2023-4966 Sensitive Info Disclosure Attempts via OIDC Endpoint
id: a987f73c-a596-42c7-ac89-e78728574dab
related:
  - id: 87c83d8e-5390-44ce-aa4a-d3b37e54d0a0
    type: similar
  - id: aee7681f-b53d-4594-a9de-ac51e6ad3362
    type: similar
  - id: a4e068b5-e27c-4f21-85b3-e69e5a4f7ce1
    type: similar
  - id: ff349b81-617f-4af4-924f-dbe8ea9bab41
    type: derived
status: test
description: 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.
references:
  - https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967
  - https://attackerkb.com/topics/2faW2CxJgQ/cve-2023-4966
  - https://www.rapid7.com/blog/post/2023/10/25/etr-cve-2023-4966-exploitation-of-citrix-netscaler-information-disclosure-vulnerability/
  - https://www.assetnote.io/resources/research/citrix-bleed-leaking-session-tokens-with-cve-2023-4966
  - https://github.com/assetnote/exploits/tree/main/citrix/CVE-2023-4966
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/Exploits/CVE-2023-4966/proxy_exploit_cve_2023_4966_citrix_sensitive_information_disclosure_exploit_attempt.yml
author: Nasreddine Bencherchali (Nextron Systems), Michael Haag (STRT), Huntrule Team
date: 2023-11-28
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2023-4966
  - detection.emerging-threats
logsource:
  category: proxy
detection:
  selection:
    cs-method: GET
    cs-uri|contains: /oauth/idp/.well-known/openid-configuration
    sc-status: 200
  condition: selection
falsepositives:
  - Vulnerability scanners
level: medium
license: DRL-1.1

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