Detect WatchGuard Firebox Out-of-Bounds Write Exploitation (CVE-2025-9242) in Microsoft Sentinel
Detects exploitation attempts targeting CVE-2025-9242, an out-of-bounds write vulnerability (CWE-787) in WatchGuard Firebox appliances. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild. Successful exploitation may allow remote code execution or denial of service on affected Firebox devices.
MITRE ATT&CK
- Tactic
- Initial Access Execution Impact
KQL Detection Query
let WatchGuardIPs = NetworkDeviceInfo
| where DeviceVendor has_any ("WatchGuard", "watchguard")
| project DeviceIP;
CommonSecurityLog
| where DeviceVendor has_any ("WatchGuard", "watchguard")
| where DeviceProduct has_any ("Firebox", "fireware")
| where Activity has_any ("crash", "segfault", "stack overflow", "memory corruption", "out of bounds", "buffer", "core dump", "exception", "fatal")
or Message has_any ("OOB", "write violation", "access violation", "heap corruption", "stack smash")
| project TimeGenerated, DeviceVendor, DeviceProduct, DeviceVersion, SourceIP, DestinationIP, Activity, Message, AdditionalExtensions
| union (
NetworkDeviceLog
| where RawLog has_any ("watchguard", "firebox", "fireware")
| where RawLog has_any ("crash", "segfault", "out of bounds", "write violation", "buffer overflow", "heap", "exception", "core dump")
| project TimeGenerated, SourceIP, RawLog
)
| order by TimeGenerated descHunts for WatchGuard Firebox crash/memory-corruption events in CommonSecurityLog and NetworkDeviceLog that may indicate out-of-bounds write exploitation (CVE-2025-9242). Correlates device vendor/product fields and anomalous error keywords.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate Firebox firmware upgrade or reboot cycles that generate crash-like log entries
- Hardware failures or power events causing unexpected process termination
- High-load DDoS traffic causing Firebox memory pressure and associated log noise
Other platforms for CVE-2025-9242
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 1Simulate OOB Write Crash via Malformed Packet to Firebox Management Port
Expected signal: WatchGuard Firebox syslog should show a connection attempt from the test host IP; if the vulnerability is present, a crash or error log entry with memory-violation language should appear within seconds of the payload delivery.
- Test 2WatchGuard Firebox VPN Endpoint Fuzzing
Expected signal: Firebox syslog should record repeated connection attempts from the fuzzer host; if an OOB write is triggered, a crash or process-restart log entry will appear.
- Test 3Verify Firebox Firmware Patch Status via Management API
Expected signal: The management API or CLI returns the current Firebox firmware version string; if the version is below the patched threshold per WGSA-2025-00015, the device is confirmed vulnerable in the lab environment.
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Get the full detection package for CVE-2025-9242 including response playbook, investigation guide, and atomic red team tests.