Detect Cisco Catalyst SD-WAN Manager Improper Output Encoding Exploitation in Microsoft Sentinel
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
KQL Detection Query
let sdwan_mgr_ips = dynamic([]);
union DeviceEvents, CommonSecurityLog, Syslog
| where TimeGenerated >= ago(24h)
| where (
(DeviceVendor == "Cisco" and DeviceProduct has_any ("SD-WAN", "vManage", "Catalyst SD-WAN Manager"))
or (Computer has_any ("vmanage", "sdwan-manager", "sdwanmgr"))
or (SourceSystem == "Syslog" and ProcessName has_any ("vmanage", "sdwan"))
)
| where Message has_any (
"privilege", "escalat", "unauthorized", "injection", "encoding", "escape",
"admin", "root", "sudo", "permission denied", "access denied", "forbidden",
"REST API", "/dataservice/", "HTTP/1"
)
| extend SuspiciousIndicators = case(
Message has_any ("privilege escalat", "unauthorized privilege"), "PrivilegeEscalation",
Message has_any ("injection", "encoding error", "escape"), "OutputEncodingAbuse",
Message has_any ("admin", "root") and Message has "failed", "AuthFailureAdminContext",
"Other"
)
| where SuspiciousIndicators != "Other"
| summarize EventCount = count(), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated), Messages = make_set(Message, 10) by Computer, SuspiciousIndicators, SourceSystem
| where EventCount >= 2
| project-reorder FirstSeen, LastSeen, Computer, SuspiciousIndicators, EventCount, MessagesHunts for suspicious activity on Cisco SD-WAN Manager nodes — privilege escalation signals, output encoding anomalies, and admin-context auth failures — correlated across Syslog, CommonSecurityLog, and DeviceEvents.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate administrative configuration changes triggering privilege-related log entries
- Routine SD-WAN Manager software upgrades generating encoding-related log noise
- Security scanners or vulnerability assessment tools probing the management API
- Misconfigured monitoring agents producing repeated auth failure messages
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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