Detect Local Account in Google Chronicle
Adversaries may attempt to get a listing of local system accounts to aid in follow-on behavior such as privilege escalation, lateral movement, or credential access. On Windows, commands such as net user and net localgroup are commonly used. On Linux and macOS, commands such as id, groups, cat /etc/passwd, and dscl . list /Users enumerate local accounts. On ESXi, esxcli system account list retrieves local accounts. This information helps adversaries understand the account landscape, identify high-value targets like local administrators, and plan further attack steps.
MITRE ATT&CK
- Tactic
- Discovery
- Technique
- T1087 Account Discovery
- Sub-technique
- T1087.001 Local Account
- Canonical reference
- https://attack.mitre.org/techniques/T1087/001/
YARA-L Detection Query
rule t1087_001_local_account_enumeration {
meta:
author = "Detection Engineering"
description = "Detects local account enumeration via net.exe, PowerShell Get-Local* cmdlets, WMIC Win32_UserAccount, or query.exe"
mitre_attack_tactic = "Discovery"
mitre_attack_technique = "T1087.001"
severity = "MEDIUM"
priority = "MEDIUM"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
(
(
re.regex($e.principal.process.file.full_path, `(?i)net(1)?\.exe$`) and
re.regex($e.principal.process.command_line, `(?i)(user|localgroup|accounts)`)
) or
(
re.regex($e.principal.process.file.full_path, `(?i)powershell\.exe$`) and
re.regex($e.principal.process.command_line, `(?i)(Get-LocalUser|Get-LocalGroup|Get-LocalGroupMember|Win32_UserAccount|Win32_UserProfile)`)
) or
(
re.regex($e.principal.process.file.full_path, `(?i)wmic\.exe$`) and
re.regex($e.principal.process.command_line, `(?i)(useraccount|win32_useraccount)`)
) or
(
re.regex($e.principal.process.file.full_path, `(?i)query\.exe$`) and
re.regex($e.principal.process.command_line, `(?i)\b(user|session)\b`)
)
)
condition:
$e
}Google Chronicle YARA-L 2.0 rule detecting T1087.001 local account enumeration. Matches PROCESS_LAUNCH UDM events where principal.process.file.full_path ends with a known enumeration binary (net.exe, net1.exe, powershell.exe, wmic.exe, query.exe) and principal.process.command_line contains account discovery keywords. Uses re.regex() with case-insensitive backtick-delimited patterns. Single-event rule firing on each qualifying process launch.
Data Sources
Required Tables
False Positives & Tuning
- Authorized privileged account audits run by IT administrators via net.exe or PowerShell management scripts under sanctioned change windows
- Service accounts used by SCCM, Microsoft Intune, or Group Policy processing that query local group membership during policy application cycles
- Corporate security tooling performing periodic CIS benchmark compliance checks that enumerate local administrators group members across endpoints
Other platforms for T1087.001
Testing Methodology
Validate this detection against 5 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 1Local Account Enumeration via net user and net localgroup
Expected signal: Sysmon Event ID 1: Three process creation events with Image=C:\Windows\System32\net.exe and CommandLine values 'net user', 'net localgroup', 'net localgroup administrators'. Security Event ID 4799 may be generated for the localgroup administrators query. Security Event ID 4688 if command-line auditing is enabled.
- Test 2Local Account Enumeration via PowerShell Get-LocalUser
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe and CommandLine containing 'Get-LocalUser', 'Get-LocalGroup', 'Get-LocalGroupMember'. PowerShell ScriptBlock Log Event ID 4104 with the full script content. Windows Security Event ID 4799 for the Administrators group membership enumeration.
- Test 3Local Account Enumeration via WMIC
Expected signal: Sysmon Event ID 1: Two process creation events with Image=C:\Windows\System32\wbem\WMIC.exe and CommandLines containing 'useraccount' and 'win32_useraccount'. Security Event ID 4688 if command-line auditing is enabled.
- Test 4Local Account Enumeration on Linux via /etc/passwd and id
Expected signal: Linux auditd syscall events: openat() or open() syscall for /etc/passwd with the UID of the executing process. Syslog or auditd process execution records for 'cat', 'cut', 'id', 'groups', 'getent', 'who' commands. In environments with Sysmon for Linux: EventCode=1 process creation events for each command.
- Test 5Local Account Enumeration via query user and Security Event Trigger
Expected signal: Sysmon Event ID 1: Two process creation events with Image=C:\Windows\System32\query.exe and CommandLines 'query user' and 'query session'. Security Event ID 4688 if process creation auditing with command lines is enabled.
References (14)
- https://attack.mitre.org/techniques/T1087/001/
- https://linux.die.net/man/1/id
- https://linux.die.net/man/1/groups
- https://www.fireeye.com/content/dam/fireeye-www/services/pdfs/mandiant-apt1-report.pdf
- https://www.crowdstrike.com/en-us/blog/hypervisor-jackpotting-ecrime-actors-increase-targeting-of-esxi-servers/
- https://www.elastic.co/security-labs/embracing-offensive-tooling-building-detections-against-koadic-using-eql
- https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/net-user
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4798
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4799
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1087.001/T1087.001.md
- https://github.com/SigmaHQ/sigma/tree/master/rules/windows/process_creation
- https://www.trendmicro.com/en_us/research/20/e/tropic-trooper-s-back-usbferry-attack-targets-air-gapped-environments.html
- https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/orangeworm-targets-healthcare-us-europe-asia
- https://www.mandiant.com/resources/operation-ke3chang-targeted-attacks-against-ministries-of-foreign-affairs
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