System Owner/User Discovery

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System Owner/User Discovery
Technique
ID T1033
Tactic Discovery
Platform Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows XP, Windows 7, Windows 8, Windows Server 2003 R2, Windows Server 2008 R2, Windows Server 2012 R2, Windows Vista, Windows 8.1, Linux
Permissions Required User, Administrator
Data Sources File monitoring, Process monitoring, Process command-line parameters
CAPEC ID CAPEC-577

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 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.

Examples

  • An APT3 downloader uses the Windows command "cmd.exe" /C whoami to verify that it is running with the elevated privileges of “System.”1
  • Lazarus Group malware SierraAlfa and WhiskeyAlfa-Three enumerate logged-on users. Lazarus Group malware IndiaIndia collects the victim's username and sends it to the C2 server.2 34
  • Stealth Falcon malware gathers the registered user and primary owner name via WMI.5
  • Patchwork collected the victim username and whether it was running as admin, then sent the information to its C2 server.6
  • A Linux version of Derusbi checks if the victim user ID is anything other than zero (normally used for root), and the malware will not execute if it does not have root privileges.7
  • SslMM sends the logged-on username to its hard-coded C2.8
  • WinMM uses NetUser-GetInfo to identify that it is running under an “Admin” account on the local system.8
  • Sys10 collects the account name of the logged-in user and sends it to the C2.8
  • Mis-Type runs tests to determine the privilege level of the compromised user.9
  • Agent.btz obtains the victim username and saves it to a file.10
  • Backdoor.Oldrea collects the current username from the victim.11
  • T9000 gathers and beacons the username of the logged in account during installation. It will also gather the username of running processes to determine if it is running as SYSTEM.12
  • A module in Prikormka collects information from the victim about the current user name.13
  • Remsec can obtain information about the current user.14
  • Unknown Logger can obtain information about the victim usernames.15
  • PowerDuke has commands to get the current user's name and SID.16

Mitigation

Identify unnecessary system utilities or potentially malicious software that may be used to acquire information about system users, and audit and/or block them by using whitelisting17 tools, like AppLocker,1819 or Software Restriction Policies20 where appropriate.21

Detection

System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities based on the information obtained.

Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

References