Citrix ADC Exploitation CVE-2023-3519

name: Citrix ADC Exploitation CVE-2023-3519
id: 76ac2dcb-333c-4a77-8ae9-2720cfae47a8
version: 9
creation_date: '2023-07-21'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: Hunting
description: |
    The following analytic identifies potential exploitation attempts against Citrix ADC related to CVE-2023-3519. It detects POST requests to specific web endpoints associated with this vulnerability by leveraging the Web datamodel.
    This activity is significant as CVE-2023-3519 involves a SAML processing overflow issue that can lead to memory corruption, posing a high risk.
    If confirmed malicious, attackers could exploit this to execute arbitrary code, escalate privileges, or disrupt services, making it crucial for SOC analysts to monitor and investigate these alerts promptly.
data_source:
    - Palo Alto Network Threat
search: |-
    | tstats `security_content_summariesonly`
             count min(_time) as firstTime
                   max(_time) as lastTime
    FROM datamodel=Web WHERE

    Web.http_method=POST
    Web.url IN (
        "*/cgi/logout",
        "*/saml/activelogin",
        "*/saml/login",
        "/cgi/samlart?samlart=*",
        "/cgi/samlauth",
        "/gwtest/formssso?event=start&target=*",
        "/netscaler/ns_gui/vpn/*"
    )
    BY Web.http_user_agent, Web.status
       Web.http_method Web.url Web.url_length
       Web.src Web.dest
    | `drop_dm_object_name("Web")`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `citrix_adc_exploitation_cve_2023_3519_filter`
how_to_implement: This detection requires the Web datamodel to be populated from a supported Technology Add-On like Splunk for Apache, Splunk for Nginx, or Splunk for Palo Alto.
known_false_positives: False positives may be present based on organization use of SAML utilities. Filter, or restrict the analytic to Citrix devices only.
references:
    - https://blog.assetnote.io/2023/07/21/citrix-CVE-2023-3519-analysis/
    - https://support.citrix.com/article/CTX561482/citrix-adc-and-citrix-gateway-security-bulletin-for-cve20233519-cve20233466-cve20233467
    - https://securityintelligence.com/x-force/x-force-uncovers-global-netscaler-gateway-credential-harvesting-campaign/
    - https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967
analytic_story:
    - Citrix Netscaler ADC CVE-2023-3519
    - CISA AA24-241A
asset_type: Network
cve:
    - CVE-2023-3519
mitre_attack_id:
    - T1190
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: web
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1190/citrix/citrix-cve20233519.log
          source: not_applicable
          sourcetype: pan:threat
      test_type: unit