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.

• 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.

• 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.

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

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

• 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.

Behavior Prevention on Endpoint refers to the use of technologies and strategies to detect and block potentially malicious activities by analyzing the behavior of processes, files, API calls, and other endpoint events. Rather than relying solely on known signatures, this approach leverages heuristics, machine learning, and real-time monitoring to identify anomalous patterns indicative of an attack.

• Implementation: Use Endpoint Detection and Response (EDR) tools to monitor and block processes exhibiting unusual behavior, such as privilege escalation attempts.
• Use Case: An attacker uses a known vulnerability to spawn a privileged process from a user-level application. The endpoint tool detects the abnormal parent-child process relationship and blocks the action.

• Implementation: Leverage Data Loss Prevention (DLP) or endpoint tools to block processes attempting to access sensitive files without proper authorization.
• Use Case: A process tries to read or modify a sensitive file located in a restricted directory, such as /etc/shadow on Linux or the SAM registry hive on Windows. The endpoint tool identifies this anomalous behavior and prevents it.

• Implementation: Implement runtime analysis tools to monitor API calls and block those associated with malicious activities.
• Use Case: A process dynamically injects itself into another process to hijack its execution. The endpoint detects the abnormal use of APIs like OpenProcess and WriteProcessMemory and terminates the offending process.

• Implementation: Use behavioral exploit prevention tools to detect and block exploits attempting to gain unauthorized access.
• Use Case: A buffer overflow exploit is launched against a vulnerable application. The endpoint detects the anomalous memory write operation and halts the process.