Detect CVE-2026-33825 - Microsoft Defender Insufficient Access Control Exploitation in IBM QRadar
Detects exploitation attempts targeting CVE-2026-33825, an insufficient granularity of access control vulnerability (CWE-1220) in Microsoft Defender. This KEV-listed vulnerability allows attackers to bypass Defender access controls, potentially disabling protections, modifying exclusions, or tampering with security configurations without appropriate privilege levels.
MITRE ATT&CK
QRadar Detection Query
SELECT
DATEFORMAT(devicetime, 'yyyy-MM-dd HH:mm:ss') AS event_time,
logsourcename(logsourceid) AS log_source,
username,
QIDNAME(qid) AS event_name,
categoryname(category) AS category,
"sourceip" AS src_ip,
"destinationip" AS dst_ip,
HOSTNAME AS host,
"Process Name" AS process_name,
"Command" AS command_line,
"Target Object" AS target_object,
magnitude
FROM events
WHERE
LOGSOURCETYPENAME(devicetype) IN ('Microsoft Windows Security Event Log', 'Microsoft Sysmon', 'Microsoft Windows Defender')
AND (
(eventid IN (5001, 5004, 5007, 5010, 5012, 5013) AND LOGSOURCETYPENAME(devicetype) = 'Microsoft Windows Defender')
OR (eventid IN (4657, 4670) AND ("Object Name" ILIKE '%Windows Defender%' OR "Object Name" ILIKE '%MsMpEng%'))
OR (
LOGSOURCETYPENAME(devicetype) = 'Microsoft Sysmon'
AND eventid IN (1, 13)
AND (
("Process Name" ILIKE '%powershell.exe' AND ("Command" ILIKE '%Set-MpPreference%' OR "Command" ILIKE '%DisableRealtimeMonitoring%' OR "Command" ILIKE '%ExclusionPath%'))
OR ("Process Name" ILIKE '%sc.exe' AND ("Command" ILIKE '%WinDefend%' OR "Command" ILIKE '%SecurityHealthService%') AND ("Command" ILIKE '%stop%' OR "Command" ILIKE '%disable%'))
OR ("Process Name" ILIKE '%reg.exe' AND "Command" ILIKE '%Windows Defender%' AND ("Command" ILIKE '% add %' OR "Command" ILIKE '% delete %'))
)
AND username NOT ILIKE '%SYSTEM%'
AND username NOT ILIKE '%TrustedInstaller%'
)
)
AND LAST 24 HOURS
ORDER BY devicetime DESC
LIMIT 500QRadar AQL query correlating Windows Defender operational events (protection state changes, config modifications), Security Event Log registry ACL changes targeting Defender keys, and Sysmon process events capturing PowerShell, sc.exe, and reg.exe Defender tampering — collectively indicating CVE-2026-33825 exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Authorized IT administrators managing Defender via approved GPO or scripting frameworks
- Enterprise software deployment systems modifying Defender exclusions for line-of-business applications
- Security operations teams running scheduled Defender health validation scripts
- MDM-driven configuration enforcement generating legitimate Defender policy change events
Other platforms for CVE-2026-33825
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 1Disable Defender Real-Time Monitoring via PowerShell (CVE-2026-33825 Simulation)
Expected signal: Sysmon EventID 1 (process creation) for powershell.exe with CommandLine containing Set-MpPreference and DisableRealtimeMonitoring; Windows Defender Operational EventID 5001 (real-time protection disabled); DeviceProcessEvents in MDE showing the PowerShell invocation
- Test 2Add Defender Exclusion Path via PowerShell
Expected signal: Sysmon EventID 1 for powershell.exe with Add-MpPreference and ExclusionPath in CommandLine; Defender Operational EventID 5007 (configuration changed) with new exclusion path; registry modification to HKLM\SOFTWARE\Microsoft\Windows Defender\Exclusions\Paths
- Test 3Stop WinDefend Service via sc.exe
Expected signal: Sysmon EventID 1 (process creation) for sc.exe with CommandLine 'sc stop WinDefend'; Windows System EventID 7036 (WinDefend service stopped); Security EventID 4689 (process exit) for MsMpEng.exe if service fully stops; Defender Operational EventID 5001
- Test 4Modify Defender Registry Key to Disable Antispyware
Expected signal: Sysmon EventID 13 (registry value set) with TargetObject HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\DisableAntiSpyware and Details=DWORD (0x00000001); Security EventID 4657 for registry write to Defender policy key; Defender Operational EventID 5007
Unlock Pro Content
Get the full detection package for CVE-2026-33825 including response playbook, investigation guide, and atomic red team tests.