Restrict Library Loading

Restricting library loading involves implementing security controls to ensure that only trusted and verified libraries (DLLs, shared objects, etc.) are loaded into processes. Adversaries often abuse Dynamic-Link Library (DLL) Injection, DLL Search Order Hijacking, or LD_PRELOAD mechanisms to execute malicious code by forcing the operating system to load untrusted libraries. This mitigation can be implemented through the following measures: Enforce Safe Library Loading Practices: - Enable `SafeDLLSearchMode` on Windows. - Restrict `LD_PRELOAD` and `LD_LIBRARY_PATH` usage on Linux systems. Code Signing Enforcement: - Require digital signatures for all libraries loaded into processes. - Use tools like Signtool, and WDAC to enforce signed DLL execution. Environment Hardening: - Secure library paths and directories to prevent adversaries from placing rogue libraries. - Monitor user-writable directories and system configurations for unauthorized changes. Audit and Monitor Library Loading: - Enable `Sysmon` on Windows to monitor for suspicious library loads. - Use `auditd` on Linux to monitor shared library paths and configuration file changes. Use Application Control Solutions: - Implement AppLocker, WDAC, or SELinux to allow only trusted libraries. *Tools for Implementation* Windows-Specific Tools: - AppLocker: Application whitelisting for DLLs. - Windows Defender Application Control (WDAC): Restrict unauthorized library execution. - Signtool: Verify and enforce code signing. - Sysmon: Monitor DLL load events (Event ID 7). Linux-Specific Tools: - auditd: Monitor changes to library paths and critical files. - SELinux/AppArmor: Define policies to restrict library loading. - ldconfig and chattr: Secure LD configuration files and prevent unauthorized modifications. Cross-Platform Solutions: - Wazuh or OSSEC: File integrity monitoring for library changes. - Tripwire: Detect and alert on unauthorized library modifications.