Detect Cisco Unified Communications Manager SSRF Exploitation Detected in Google Chronicle
Detects exploitation attempts of CVE-2026-20230, a Server-Side Request Forgery (SSRF) vulnerability in Cisco Unified Communications Manager (CUCM). An unauthenticated remote attacker may craft malicious HTTP requests to the CUCM web interface to cause the server to initiate requests to arbitrary internal or external destinations, potentially enabling internal network reconnaissance, credential theft via metadata services, or pivoting to internal resources.
MITRE ATT&CK
YARA-L Detection Query
rule cisco_cucm_ssrf_cve_2026_20230 {
meta:
author = "df00tech Detection Engineering"
description = "Detects SSRF exploitation of CVE-2026-20230 in Cisco Unified Communications Manager"
severity = "HIGH"
priority = "HIGH"
reference = "https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-cucm-ssrf-cXPnHcW.html"
cve = "CVE-2026-20230"
events:
$e.metadata.event_type = "NETWORK_HTTP"
$e.target.application = /(?i)(unified communications manager|cucm|call manager)/
(
$e.network.http.request_url = /(?i)(169\.254\.169\.254|metadata\.google\.internal|100\.100\.100\.200)/ or
$e.network.http.request_url = /(?i)(127\.0\.0\.1|localhost|::1|0\.0\.0\.0)/ or
$e.network.http.request_url = /(?i)(file://|dict://|gopher://|ldap://)/ or
$e.network.http.request_url = /(?i)(/ccmadmin/|/cucm-uds/|/ucmuser/|/ccmuser/|/cmplatform/).*url=/
)
$e.principal.ip = $src_ip
condition:
$e
}Chronicle YARA-L rule to detect HTTP requests to Cisco CUCM containing SSRF payload indicators such as metadata service addresses, loopback IPs, or non-standard URI schemes embedded in request parameters.
Data Sources
Required Tables
False Positives & Tuning
- Authorized red team exercises using SSRF payloads against CUCM in controlled environments
- Legitimate cluster health-check scripts that resolve CUCM nodes via internal IP parameters
- Third-party CUCM integrations that pass internal callback addresses for event notification
- Misconfigured reverse proxies forwarding internal address headers through CUCM endpoints
Other platforms for CVE-2026-20230
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1SSRF Probe via CUCM Admin Interface URL Parameter
Expected signal: HTTP GET request to /ccmadmin/ with redirectUrl parameter containing 169.254.169.254; subsequent outbound TCP connection from CUCM server to 169.254.169.254:80 if vulnerable
- Test 2SSRF via Gopher Protocol Scheme in CUCM API Parameter
Expected signal: HTTP GET to /cucm-uds/ endpoint with gopher:// scheme in callback parameter; potential TCP connection from CUCM server to 127.0.0.1:6379 if exploitable
- Test 3SSRF Internal Network Scan via CUCM Redirect Parameter
Expected signal: Multiple HTTP requests to /ccmuser/ with varying port numbers in src parameter containing RFC1918 addresses; timing differences in responses may reveal open ports on internal hosts if CUCM is vulnerable
References (4)
- https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-cucm-ssrf-cXPnHcW.html
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-20230
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