Detect Hidden Users in Elastic Security
Adversaries may use hidden users to hide the presence of user accounts they create or modify. On Windows, accounts can be hidden from the login screen by setting a registry value under HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList with a DWORD value of 0 for the username. On macOS, adversaries can set a user's UID below 500 or set a UserShell property to /usr/bin/false to hide them. Threat actors including Dragonfly, Kimsuky, and SMOKEDHAM malware use hidden user accounts for persistent backdoor access.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1564 Hide Artifacts
- Sub-technique
- T1564.002 Hidden Users
- Canonical reference
- https://attack.mitre.org/techniques/T1564/002/
Elastic Detection Query
any where (
(event.category == "registry" and event.type in ("creation", "change") and
registry.path like "*Winlogon\\SpecialAccounts\\UserList*")
or
(event.category == "process" and event.type == "start" and
process.name in~ ("net.exe", "net1.exe") and
process.args : "user" and process.args : "/add")
or
(event.category == "iam" and event.action in ("user-created", "added-user-account"))
)Detects hidden user account creation on Windows by monitoring registry modifications to the SpecialAccounts\UserList key (which hides users from the login screen), net.exe user add commands, and IAM user creation events.
Data Sources
Required Tables
False Positives & Tuning
- System administrators legitimately hiding service or kiosk accounts from the Windows login screen using SpecialAccounts\UserList for UI cleanliness
- IT provisioning scripts that create user accounts in bulk using net.exe as part of automated onboarding workflows
- Security tools or endpoint management software (e.g., SCCM, Intune) that create local accounts during software deployment
Other platforms for T1564.002
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 1Create Hidden User Account via Registry
Expected signal: Windows Security Event ID 4720 (User Account Created) for HiddenTestUser. Sysmon Event ID 13 (Registry Value Set) for the SpecialAccounts key. Security Event ID 4688 for net.exe and reg.exe process creation.
- Test 2Create Hidden Admin User Account
Expected signal: Security Event ID 4720 (user created), 4732 (added to Administrators group), 4688 for net.exe x2 and reg.exe. Sysmon EventCode=13 for SpecialAccounts registry modification.
- Test 3Enumerate Hidden User Accounts
Expected signal: Security Event ID 4688 for reg.exe process creation. The query itself does not create events but identifies existing hidden accounts. No registry write events are generated.
References (4)
- https://attack.mitre.org/techniques/T1564/002/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1564.002/T1564.002.md
- https://docs.microsoft.com/en-us/windows/win32/secauthn/winlogon-and-credential-providers
- https://www.mandiant.com/resources/blog/smokedham-backdoor-delivers-cobalt-strike
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