Detect Microsoft Windows Information Disclosure (CVE-2026-20805) in Splunk
Detects exploitation of CVE-2026-20805, a Microsoft Windows information disclosure vulnerability (CWE-200) that allows attackers to access sensitive memory or kernel data. This vulnerability is actively exploited in the wild (CISA KEV). Successful exploitation may expose credentials, memory contents, or system information that enables privilege escalation or lateral movement.
MITRE ATT&CK
SPL Detection Query
index=wineventlog OR index=sysmon sourcetype IN ("WinEventLog:Security", "XmlWinEventLog:Microsoft-Windows-Sysmon/Operational")
| eval is_suspicious_api = if(match(CommandLine, "NtQuerySystemInformation|ZwQuerySystemInformation|ReadProcessMemory|VirtualQueryEx"), 1, 0)
| eval is_low_integrity = if(match(IntegrityLevel, "(?i)low|medium"), 1, 0)
| eval is_sensitive_access = if(EventCode IN ("4663", "4656") AND match(ObjectName, "(?i)lsass|sam|security|ntds"), 1, 0)
| eval suspicion_score = (is_suspicious_api * 2) + (is_low_integrity * 1) + (is_sensitive_access * 3)
| where suspicion_score >= 2
| eval host_time = strftime(_time, "%Y-%m-%d %H:%M:%S")
| stats count AS event_count, max(suspicion_score) AS max_score, values(CommandLine) AS commands, values(EventCode) AS event_codes, values(ObjectName) AS objects BY host, User, host_time
| where event_count >= 1
| sort - max_score, - event_count
| table host_time, host, User, event_count, max_score, commands, event_codes, objectsDetects CVE-2026-20805 exploitation indicators in Windows event logs and Sysmon telemetry by correlating low-integrity process API calls to kernel information disclosure functions with sensitive object access events (4663/4656) targeting LSASS, SAM, or NTDS.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Security tooling (vulnerability scanners, EDR agents) that legitimately access sensitive objects
- IT automation scripts running under standard user accounts with delegated permissions
- Legitimate forensics or incident response tooling performing memory reads
- Software auditing tools reading process information for license enforcement
Other platforms for CVE-2026-20805
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 1NtQuerySystemInformation via PowerShell P/Invoke
Expected signal: Sysmon Event ID 1 (Process Create) for powershell.exe; Windows Event ID 4688 if process command line auditing is enabled; EDR process telemetry capturing the PowerShell invocation with P/Invoke patterns.
- Test 2LSASS Handle Open with VM_READ Access
Expected signal: Sysmon Event ID 10 (ProcessAccess) with TargetImage=lsass.exe, GrantedAccess=0x0010 (PROCESS_VM_READ), SourceImage=powershell.exe; Windows Security Event ID 4656 for handle request to LSASS process object.
- Test 3Sensitive Registry Hive Access from Low Integrity Context
Expected signal: Windows Security Event ID 4663 with ObjectName containing SECURITY hive path; Sysmon Event ID 1 for process creation with low integrity level token; Event ID 4656 for registry key open with sensitive access mask.
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