Detect CVE-2025-20393 — Cisco Multiple Products Improper Input Validation (KEV) in Microsoft Sentinel
Detects exploitation attempts targeting CVE-2025-20393, an improper input validation vulnerability (CWE-20) affecting Cisco Multiple Products. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active in-the-wild exploitation. Attackers may leverage this flaw to bypass security controls, execute unauthorized commands, or gain elevated access to affected Cisco appliances.
MITRE ATT&CK
KQL Detection Query
union DeviceNetworkEvents, CommonSecurityLog
| where TimeGenerated >= ago(7d)
| where DeviceVendor == "Cisco" or SourceSystem contains "Cisco"
| where (RequestURL contains "sma" and (RequestURL matches regex @"(?i)(\.\./|%2e%2e%2f|%252e|;|%3b|\x00|null%00)")
or Activity contains "input validation"
or AdditionalExtensions contains "CVE-2025-20393")
| extend AttackerIP = coalesce(SourceIP, RemoteIP)
| extend TargetDevice = coalesce(DeviceName, Computer, DestinationHostName)
| project TimeGenerated, AttackerIP, TargetDevice, RequestURL, Activity, AdditionalExtensions, SourceSystem
| order by TimeGenerated descHunts for improper input validation exploitation patterns against Cisco products, including path traversal sequences and malformed input in HTTP requests logged via CommonSecurityLog or Defender for Endpoint network telemetry.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate security scanning tools (Nessus, Qualys) performing authenticated vulnerability assessments
- Penetration testers running authorized assessments against Cisco infrastructure
- Misconfigured monitoring agents producing malformed log entries with unusual characters
Other platforms for CVE-2025-20393
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 1Path Traversal Probe Against Cisco SMA Interface
Expected signal: HTTP request log entry with URI containing '../' sequences recorded in Cisco SMA access log; network flow record from test host to Cisco appliance on port 443
- Test 2Null Byte Injection Input Validation Test
Expected signal: HTTP request containing '%00' in query string logged by network proxy or Cisco appliance; potential error response indicating input validation failure
- Test 3Automated Exploitation Pattern Simulation with Repeated Requests
Expected signal: Ten sequential HTTP requests with encoded path traversal sequences from same source IP within 10 seconds, logged across Cisco access logs and network flow telemetry
Unlock Pro Content
Get the full detection package for CVE-2025-20393 including response playbook, investigation guide, and atomic red team tests.