T1564.002: Hidden Users
Hidden Users (T1564.002) é uma técnica catalogada no MITRE ATT&CK Enterprise usada como referência para mapear comportamento adversário em auditorias de segurança.
Contexto para AppSec
Em uma auditoria de AppSec, Hidden Users deve ser usada para revisar caminhos em que código, configuração, dependências ou infraestrutura podem viabilizar o comportamento descrito pela MITRE. No ATT&CK, ela aparece em Stealth. As plataformas mapeadas pela MITRE incluem Linux, macOS e Windows. No Vigly, esse contexto ajuda a conectar evidências do repositório com priorização e remediação.
Descrição oficial original do MITRE ATT&CK
Adversaries may use hidden users to hide the presence of user accounts they create or modify. Administrators may want to hide users when there are many user accounts on a given system or if they want to hide their administrative or other management accounts from other users. In macOS, adversaries can create or modify a user to be hidden through manipulating plist files, folder attributes, and user attributes. To prevent a user from being shown on the login screen and in System Preferences, adversaries can set the userID to be under 500 and set the key value Hide500Users to TRUE in the /Library/Preferences/com.apple.loginwindow plist file. Every user has a userID associated with it. When the Hide500Users key value is set to TRUE, users with a userID under 500 do not appear on the login screen and in System Preferences. Using the command line, adversaries can use the dscl utility to create hidden user accounts by setting the IsHidden attribute to 1. Adversaries can also hide a user’s home folder by changing the chflags to hidden. Adversaries may similarly hide user accounts in Windows. Adversaries can set the HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList Registry key value to 0 for a specific user to prevent that user from being listed on the logon screen. On Linux systems, adversaries may hide user accounts from the login screen, also referred to as the greeter. The method an adversary may use depends on which Display Manager the distribution is currently using. For example, on an Ubuntu system using the GNOME Display Manger (GDM), accounts may be hidden from the greeter using the gsettings command (ex: sudo -u gdm gsettings set org.gnome.login-screen disable-user-list true). Display Managers are not anchored to specific distributions and may be changed by a user or adversary.
Como o Vigly audita a técnica Hidden Users automaticamente na sua pipeline
O Vigly cruza sinais de SAST, modelagem de ameaças, regras de negócio e evidências do repositório para priorizar riscos reais antes que eles cheguem à produção.
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