Detect Microsoft Windows Improper Privilege Management (CVE-2026-21533) in CrowdStrike LogScale
Detects exploitation of CVE-2026-21533, a Microsoft Windows Improper Privilege Management vulnerability (CWE-269) listed in CISA's Known Exploited Vulnerabilities catalog. Successful exploitation allows a local attacker to elevate privileges on a compromised Windows system. Detection focuses on anomalous privilege token manipulation, unexpected service/process privilege escalation, and suspicious access patterns consistent with local privilege escalation techniques.
MITRE ATT&CK
- Tactic
- Privilege Escalation Persistence
LogScale Detection Query
#event_simpleName=ProcessRollup2
| UserName != "SYSTEM"
| UserName != "LOCAL SERVICE"
| UserName != "NETWORK SERVICE"
| UserName !~ regex(".*\\$$")
| IntegrityLevel in ("High", "System")
| TokenPrivileges = /SeDebugPrivilege|SeTcbPrivilege|SeLoadDriverPrivilege|SeAssignPrimaryTokenPrivilege|SeTakeOwnershipPrivilege/
| ParentIntegrityLevel in ("Low", "Medium")
| groupBy([UserName, ComputerName, ParentProcessId, ParentBaseFileName, FileName, CommandLine, IntegrityLevel, TokenPrivileges], function=count())
| where _count >= 1
| sort(field=_count, order=desc)
| rename _count as EscalationEvents
| select([UserName, ComputerName, ParentBaseFileName, FileName, CommandLine, IntegrityLevel, TokenPrivileges, EscalationEvents])CrowdStrike Falcon LogScale query detecting processes launched at high or system integrity from a lower-integrity parent process with sensitive privilege tokens, a pattern consistent with local privilege escalation exploitation.
Data Sources
Required Tables
False Positives & Tuning
- CrowdStrike sensor itself may appear with elevated integrity during protection operations
- Windows Installer (msiexec.exe) elevating from a user context during software installation
- Group Policy client-side extensions executing with elevated privileges during policy refresh
- Third-party privilege management solutions (BeyondTrust, CyberArk) that legitimately broker privilege elevation
Other platforms for CVE-2026-21533
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 1Token Impersonation via SeDebugPrivilege
Expected signal: Windows Security Event ID 4673 (SeDebugPrivilege requested) and 4688 (new process: powershell.exe) with Medium integrity initiating a SeDebugPrivilege request.
- Test 2Process Launch at High Integrity from Medium Integrity Parent
Expected signal: Event ID 4688 showing cmd.exe launched at High integrity (MandatoryLabel S-1-16-12288) with schtasks.exe as the initiating process from a Medium-integrity user session.
- Test 3Sensitive Privilege Enumeration via Token Inspection
Expected signal: Event ID 4688 for cmd.exe and powershell.exe, potential Event ID 4672 if running in an elevated session. Process command line arguments visible in EDR telemetry.
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