Citrix ADC Exploitation CVE-2023-3519

Name:Citrix ADC Exploitation CVE-2023-3519
id:76ac2dcb-333c-4a77-8ae9-2720cfae47a8
version:10
date:None
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",
"*/cgi/samlart?samlart=*",
"*/cgi/samlauth",
"*/gwtest/formssso?event=start&target=*",
"*/netscaler/ns_gui/vpn/*",
"*/saml/activelogin",
"*/saml/login"
)

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
drilldown_searches:
  :
analytic_story:['Citrix Netscaler ADC CVE-2023-3519', 'CISA AA24-241A']

asset_type:Network

mitre_attack_id:['T1190']

product:['Splunk Enterprise', 'Splunk Enterprise Security', 'Splunk Cloud']

category:web

security_domain:endpoint

tags:

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'
manual_test:None