Time Providers

Detect Abuse of Windows Time Providers for Persistence

Restrict Registry Permissions: Restricting registry permissions involves configuring access control settings for sensitive registry keys and hives to ensure that only authorized users or processes can make modifications. By limiting access, organizations can prevent unauthorized changes that adversaries might use for persistence, privilege escalation, or defense evasion. This mitigation can be implemented through the following measures:

Review and Adjust Permissions on Critical Keys

• Regularly review permissions on keys such as Run, RunOnce, and Services to ensure only authorized users have write access.
• Use tools like icacls or PowerShell to automate permission adjustments.

Enable Registry Auditing

• Enable auditing on sensitive keys to log access attempts.
• Use Event Viewer or SIEM solutions to analyze logs and detect suspicious activity.
• Example Audit Policy: auditpol /set /subcategory:"Registry" /success:enable /failure:enable

Protect Credential-Related Hives

• Limit access to hives like SAM,SECURITY, and SYSTEM to prevent credential dumping or other unauthorized access.
• Use LSA Protection to add an additional security layer for credential storage.

Restrict Registry Editor Usage

• Use Group Policy to restrict access to regedit.exe for non-administrative users.
• Block execution of registry editing tools on endpoints where they are unnecessary.

Deploy Baseline Configuration Tools

• Use tools like Microsoft Security Compliance Toolkit or CIS Benchmarks to apply and maintain secure registry configurations.

Tools for Implementation

Registry Permission Tools:

• Registry Editor (regedit): Built-in tool to manage registry permissions.
• PowerShell: Automate permissions and manage keys. Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Run" -Name "KeyName" -Value "Value"
• icacls: Command-line tool to modify ACLs.

Monitoring Tools:

• Sysmon: Monitor and log registry events.
• Event Viewer: View registry access logs.

Policy Management Tools:

• Group Policy Management Console (GPMC): Enforce registry permissions via GPOs.
• Microsoft Endpoint Manager: Deploy configuration baselines for registry permissions.

Restrict File and Directory Permissions: Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files.

Enforce Least Privilege Permissions:

• Remove unnecessary write permissions on sensitive files and directories.
• Use file ownership and groups to control access for specific roles.

Example (Windows): Right-click the shared folder → Properties → Security tab → Adjust permissions for NTFS ACLs.

Harden File Shares:

• Disable anonymous access to shared folders.
• Enforce NTFS permissions for shared folders on Windows.

Example: Set permissions to restrict write access to critical files, such as system executables (e.g., /bin or /sbin on Linux). Use tools like chown and chmod to assign file ownership and limit access.

On Linux, apply: chmod 750 /etc/sensitive.conf chown root:admin /etc/sensitive.conf

File Integrity Monitoring (FIM):

• Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions.

Audit File System Access:

• Enable auditing to track permission changes or unauthorized access attempts.
• Use auditd (Linux) or Event Viewer (Windows) to log activities.

Restrict Startup Directories:

• Configure permissions to prevent unauthorized writes to directories like C:\ProgramData\Microsoft\Windows\Start Menu.

Example: Restrict write access to critical directories like /etc/, /usr/local/, and Windows directories such as C:\Windows\System32.

• On Windows, use icacls to modify permissions: icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F
• On Linux, monitor permissions using tools like lsattr or auditd.