Detect CVE-2025-62221 Microsoft Windows Use After Free Exploitation in Google Chronicle
Detects exploitation attempts of CVE-2025-62221, a use-after-free vulnerability in Microsoft Windows. This class of memory corruption flaw allows attackers to execute arbitrary code by manipulating freed memory objects. As a CISA KEV entry, active exploitation in the wild has been confirmed. Detection focuses on anomalous process behavior, kernel-mode memory corruption indicators, crash telemetry, and privilege escalation patterns consistent with UAF exploitation chains.
MITRE ATT&CK
- Tactic
- Privilege Escalation Execution
YARA-L Detection Query
rule cve_2025_62221_windows_uaf_exploitation {
meta:
author = "df00tech"
description = "Detects CVE-2025-62221 Windows use-after-free exploitation via anomalous process ancestry"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-62221"
cve = "CVE-2025-62221"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
$e.principal.process.parent_process.file.full_path = /(?i)\\(lsass|csrss|winlogon|services|svchost)\.exe$/
not $e.target.process.file.full_path = /(?i)\\(lsass|csrss|winlogon|services|svchost|conhost|WerFault|wermgr)\.exe$/
$e.target.process.integrity_level_name = "HIGH" or $e.target.process.integrity_level_name = "SYSTEM"
condition:
$e
}Chronicle YARA-L rule detecting elevated process launches from Windows system process parents, characteristic of CVE-2025-62221 use-after-free privilege escalation exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Windows OS components spawning elevated helper processes as part of legitimate update or repair operations
- Google Workspace or enterprise MDM solutions using elevated system-parent context
- Antivirus remediation processes spawning from system parents during threat response
Other platforms for CVE-2025-62221
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 UAF-style anomalous child process from lsass.exe parent (lab only)
Expected signal: Sysmon Event ID 1 with ParentImage pointing to lsass.exe and Image of cmd.exe; Windows Security EventID 4688 with anomalous parent-child relationship
- Test 2WER crash trigger on system process to simulate pre-exploit crash artifacts
Expected signal: Windows Event ID 1000 (Application Error) and 1001 (Windows Error Reporting) in Application event log; WER report created in %LOCALAPPDATA%\Microsoft\Windows\WER\ReportQueue
- Test 3Elevated token process launch from spoofed system parent context
Expected signal: Sysmon Event ID 1 showing cmd.exe with IntegrityLevel=System spawned by psexec service; Windows Security EventID 4688 with elevated token; EventID 4672 (special privileges assigned to new logon)
- Test 4Heap spray pattern simulation via PowerShell memory allocation
Expected signal: PowerShell Script Block Logging (EventID 4104) capturing the allocation loop; potential AMSI or Defender behavioral alert on large sequential memory allocation patterns
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