Detect Microsoft Windows Information Disclosure (CVE-2026-20805) in Elastic Security
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
Elastic Detection Query
sequence by host.name, user.name with maxspan=5m
[process where event.type == "start"
and (process.name in ("powershell.exe", "cmd.exe", "wscript.exe", "cscript.exe", "rundll32.exe", "regsvr32.exe") or
process.code_signature.trusted == false)
and process.token.integrity_level_name in ("low", "medium")]
[any where event.category == "process"
and (process.args_count >= 1 and
(
process.args : ("*NtQuerySystemInformation*", "*ZwQuerySystemInformation*", "*ReadProcessMemory*", "*OpenProcess*") or
winlog.event_data.CallTrace : ("*ntdll.dll*", "*kernelbase.dll*")
))]
[file where event.action in ("open", "read")
and file.path : ("*\\System32\\config\\SAM", "*\\System32\\config\\SECURITY", "*\\NTDS\\ntds.dit", "*\\lsass.exe")]EQL sequence rule detecting CVE-2026-20805 exploitation pattern: a low/medium integrity process spawning and subsequently making kernel API calls (NtQuerySystemInformation family) followed by access to sensitive Windows credential stores or LSASS.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate administrative tools that enumerate system information before performing maintenance tasks
- Security products running under user-level integrity that access kernel APIs for monitoring
- Custom enterprise software that reads system configuration files with delegated file permissions
- Penetration testing frameworks during authorized engagements
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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