Detect Microsoft Windows Type Confusion Vulnerability (CVE-2026-21519) in Microsoft Sentinel
Detects exploitation of CVE-2026-21519, a type confusion vulnerability (CWE-843) in Microsoft Windows. Type confusion vulnerabilities occur when code allocates or initializes a resource using one type but accesses it using an incompatible type, leading to out-of-bounds memory access, arbitrary code execution, or privilege escalation. This CVE is listed on the CISA Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
MITRE ATT&CK
KQL Detection Query
union SecurityEvent, DeviceProcessEvents, DeviceEvents
| where TimeGenerated >= ago(7d)
| where (EventID in (4688, 4697, 7045) or ActionType in ("ProcessCreated", "DriverLoad", "ImageLoaded"))
| extend ProcessCmdLine = coalesce(CommandLine, ProcessCommandLine, "")
| extend ParentProcessName = coalesce(ParentProcessName, InitiatingProcessFileName, "")
| where (
(EventID == 4688 and ProcessCmdLine has_any ("SeDebugPrivilege", "SeImpersonatePrivilege", "SeAssignPrimaryTokenPrivilege"))
or (ActionType == "DriverLoad" and not(InitiatingProcessFileName has_any ("MsMpEng.exe", "services.exe", "wininit.exe")))
or (ActionType == "ProcessCreated" and InitiatingProcessFileName in~ ("lsass.exe", "winlogon.exe", "csrss.exe") and not(FileName in~ ("conhost.exe", "werfault.exe")))
or (EventID == 4697 and ServiceFileName has_any (".tmp", "\\AppData\\", "\\Temp\\"))
)
| extend RiskScore = case(
ActionType == "DriverLoad" and not(InitiatingProcessFileName has_any ("MsMpEng.exe", "services.exe")), 90,
ActionType == "ProcessCreated" and InitiatingProcessFileName in~ ("lsass.exe", "winlogon.exe"), 85,
EventID == 4697 and ServiceFileName has_any (".tmp", "\\AppData\\"), 80,
60
)
| project TimeGenerated, Computer, AccountName, ProcessName = coalesce(NewProcessName, FileName, ""), ParentProcessName, ProcessCmdLine, ActionType, EventID, RiskScore
| sort by RiskScore desc, TimeGenerated descDetects indicators of Windows type confusion exploitation including abnormal privilege token manipulation, suspicious driver loads from non-system processes, unusual child processes spawned by protected system processes, and services installed from temporary locations.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate driver installations from third-party security software or hardware vendors
- System administrators manually installing services or drivers for maintenance
- Software update processes temporarily writing executables to AppData or Temp directories
- Debugging tools legitimately requesting SeDebugPrivilege during authorized testing
Other platforms for CVE-2026-21519
Testing Methodology
Validate this detection against 4 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 Anomalous Child Process from Winlogon
Expected signal: Sysmon EventID 1 showing cmd.exe or similar process with an unexpected parent, Windows Security EventID 4688 capturing the new process creation with command line arguments.
- Test 2Privilege Token Enumeration via Command Line
Expected signal: Windows Security EventID 4688 with CommandLine containing privilege-related arguments, Sysmon EventID 1 capturing the full process creation with integrity level.
- Test 3Suspicious Service Installation from Temp Directory
Expected signal: Windows System EventID 7045 (new service installed) with ServiceImagePath pointing to %TEMP%, Sysmon EventID 13 capturing registry writes for the new service key under HKLM\SYSTEM\CurrentControlSet\Services.
- Test 4Unsigned Driver Load Simulation via Sysmon
Expected signal: Sysmon EventID 6 (DriverLoad) with the ImageLoaded path pointing to a non-standard location and the initiating process being a user-mode application rather than services.exe or wininit.exe.
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