Detect Cisco Catalyst SD-WAN Manager Improper Output Encoding Exploitation in Google Chronicle
Detects exploitation attempts targeting CVE-2026-20245, an improper encoding or escaping of output vulnerability (CWE-116) in Cisco Catalyst SD-WAN Manager. This vulnerability is actively exploited in the wild (CISA KEV) and may allow attackers to perform privilege escalation or inject malicious content through improperly encoded output. Detection focuses on anomalous authentication patterns, unexpected privilege changes, API abuse, and suspicious management plane activity against SD-WAN Manager instances.
MITRE ATT&CK
YARA-L Detection Query
rule CVE_2026_20245_Cisco_SDWAN_Output_Encoding_Exploitation {
meta:
author = "df00tech Detection Engineering"
description = "Detects potential exploitation of CVE-2026-20245 in Cisco Catalyst SD-WAN Manager"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-privesc-4uxFrdzx"
events:
($e1.metadata.product_name = /vmanage|sd-wan manager|catalyst sd-wan/i
or $e1.target.hostname = /vmanage|sdwan.?manager|sdwanmgr/i)
and (
$e1.metadata.description = /privilege.escal/i
or $e1.metadata.description = /unauthorized.*admin/i
or $e1.metadata.description = /output.*encod.*error/i
or $e1.metadata.description = /escape.*fail/i
or ($e1.network.http.response_code = 401 and $e1.network.http.request_url = /\/dataservice\//)
or ($e1.network.http.response_code = 403 and $e1.network.http.request_url = /\/dataservice\//)
)
match:
$e1.target.hostname over 10m
outcome:
$risk_score = max(85)
$target_host = $e1.target.hostname
$product = $e1.metadata.product_name
condition:
#e1 >= 2
}Chronicle YARA-L rule detecting multiple CVE-2026-20245 exploitation indicators on Cisco SD-WAN Manager hosts — privilege escalation messages, encoding errors, and repeated API auth failures — within a 10-minute window.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate SD-WAN Manager administrative configuration tasks generating privilege-related events
- Automated orchestration platforms triggering multiple API authentication attempts
- SD-WAN Manager diagnostic or telemetry processes producing encoding-related log output
- Authorized red team or penetration testing activities against SD-WAN infrastructure
Other platforms for CVE-2026-20245
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 1SD-WAN Manager REST API Endpoint Enumeration and Auth Probe
Expected signal: Web server access logs and SD-WAN Manager audit logs should record multiple 401/403 responses to /dataservice/ endpoints from the probe source IP within a short time window
- Test 2Simulate Output Encoding Bypass via Crafted API Payload
Expected signal: SD-WAN Manager application logs should record the API request with the encoded payload; web access logs capture the POST to /dataservice/users with unexpected encoded characters in request body
- Test 3Post-Exploitation Privilege Escalation Simulation via vManage Admin API
Expected signal: SD-WAN Manager audit logs should record the group membership change attempt; if successful, an entry will appear under Administration > Audit Log showing the privilege modification with source IP and timestamp
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