Restrict File and Directory Permissions

Restrict access by setting directory and file permissions that are not specific to users or privileged accounts.

ID: M1022

Version: 1.1

Created: 06 June 2019

Last Modified: 20 May 2020

Techniques Addressed by Mitigation

Domain	ID		Name	Use
Enterprise	T1548		Abuse Elevation Control Mechanism	The sudoers file should be strictly edited such that passwords are always required and that users can't spawn risky processes as users with higher privilege.
		.003	Sudo and Sudo Caching	The sudoers file should be strictly edited such that passwords are always required and that users can't spawn risky processes as users with higher privilege.
Enterprise	T1098	.004	Account Manipulation: SSH Authorized Keys	Restrict access to the `authorized_keys` file.
Enterprise	T1547	.003	Boot or Logon Autostart Execution: Time Providers	Consider using Group Policy to configure and block additions/modifications to W32Time DLLs. ^[1]
		.011	Boot or Logon Autostart Execution: Plist Modification	Prevent plist files from being modified by users by making them read-only.
Enterprise	T1037		Boot or Logon Initialization Scripts	Restrict write access to logon scripts to specific administrators.
		.002	Logon Script (Mac)	Restrict write access to logon scripts to specific administrators.
		.003	Network Logon Script	Restrict write access to logon scripts to specific administrators.
		.005	Startup Items	Since StartupItems are deprecated, preventing all users from writing to the `/Library/StartupItems` directory would prevent any startup items from getting registered.
		.004	Rc.common	Limit privileges of user accounts so only authorized users can edit the rc.common file.
Enterprise	T1543		Create or Modify System Process	Restrict read/write access to system-level process files to only select privileged users who have a legitimate need to manage system services.
		.002	Systemd Service	Restrict read/write access to systemd unit files to only select privileged users who have a legitimate need to manage system services.
Enterprise	T1530		Data from Cloud Storage Object	Use access control lists on storage systems and objects.
Enterprise	T1565		Data Manipulation	Ensure least privilege principles are applied to important information resources to reduce exposure to data manipulation risk.
		.001	Stored Data Manipulation	Ensure least privilege principles are applied to important information resources to reduce exposure to data manipulation risk.
		.003	Runtime Data Manipulation	Prevent critical business and system processes from being replaced, overwritten, or reconfigured to load potentially malicious code.
Enterprise	T1546	.004	Event Triggered Execution: .bash_profile and .bashrc	Making these files immutable and only changeable by certain administrators will limit the ability for adversaries to easily create user level persistence.
		.013	Event Triggered Execution: PowerShell Profile	Making PowerShell profiles immutable and only changeable by certain administrators will limit the ability for adversaries to easily create user level persistence.
Enterprise	T1222		File and Directory Permissions Modification	Applying more restrictive permissions to files and directories could prevent adversaries from modifying the access control lists.
		.001	Windows File and Directory Permissions Modification	Applying more restrictive permissions to files and directories could prevent adversaries from modifying the access control lists.
		.002	Linux and Mac File and Directory Permissions Modification	Applying more restrictive permissions to files and directories could prevent adversaries from modifying the access control lists.
Enterprise	T1564	.004	Hide Artifacts: NTFS File Attributes	Consider adjusting read and write permissions for NTFS EA, though this should be tested to ensure routine OS operations are not impeded. ^[2]
Enterprise	T1574		Hijack Execution Flow	Install software in write-protected locations. Set directory access controls to prevent file writes to the search paths for applications, both in the folders where applications are run from and the standard library folders.
		.009	Path Interception by Unquoted Path	Ensure that proper permissions and directory access control are set to deny users the ability to write files to the top-level directory `C:` and system directories, such as `C:\Windows\`, to reduce places where malicious files could be placed for execution. Require that all executables be placed in write-protected directories.
		.007	Path Interception by PATH Environment Variable	Ensure that proper permissions and directory access control are set to deny users the ability to write files to the top-level directory `C:` and system directories, such as `C:\Windows\`, to reduce places where malicious files could be placed for execution. Require that all executables be placed in write-protected directories.
		.008	Path Interception by Search Order Hijacking	Ensure that proper permissions and directory access control are set to deny users the ability to write files to the top-level directory `C:` and system directories, such as `C:\Windows\`, to reduce places where malicious files could be placed for execution. Require that all executables be placed in write-protected directories.
		.002	DLL Side-Loading	Install software in write-protected locations.
		.004	Dylib Hijacking	Set directory access controls to prevent file writes to the search paths for applications, both in the folders where applications are run from and the standard dylib folders.
Enterprise	T1562		Impair Defenses	Ensure proper process and file permissions are in place to prevent adversaries from disabling or interfering with security/logging services.
		.001	Disable or Modify Tools	Ensure proper process and file permissions are in place to prevent adversaries from disabling or interfering with security services.
		.002	Disable Windows Event Logging	Ensure proper process and file permissions are in place to prevent adversaries from disabling or interfering logging.
		.004	Disable or Modify System Firewall	Ensure proper process and file permissions are in place to prevent adversaries from disabling or modifying firewall settings.
		.006	Indicator Blocking	Ensure event tracers/forwarders ^[3], firewall policies, and other associated mechanisms are secured with appropriate permissions and access controls.
Enterprise	T1070		Indicator Removal on Host	Protect generated event files that are stored locally with proper permissions and authentication and limit opportunities for adversaries to increase privileges by preventing Privilege Escalation opportunities.
		.001	Clear Windows Event Logs	Protect generated event files that are stored locally with proper permissions and authentication and limit opportunities for adversaries to increase privileges by preventing Privilege Escalation opportunities.
		.002	Clear Linux or Mac System Logs	Protect generated event files that are stored locally with proper permissions and authentication and limit opportunities for adversaries to increase privileges by preventing Privilege Escalation opportunities.
		.003	Clear Command History	Preventing users from deleting or writing to certain files can stop adversaries from maliciously altering their `~/.bash_history` or `ConsoleHost_history.txt` files.
Enterprise	T1036		Masquerading	Use file system access controls to protect folders such as C:\Windows\System32.
		.003	Rename System Utilities	Use file system access controls to protect folders such as C:\Windows\System32.
		.005	Match Legitimate Name or Location	Use file system access controls to protect folders such as C:\Windows\System32.
Enterprise	T1055	.009	Process Injection: Proc Memory	Restrict the permissions on sensitive files such as `/proc/[pid]/maps` or `/proc/[pid]/mem`.
Enterprise	T1563	.001	Remote Service Session Hijacking: SSH Hijacking	Ensure proper file permissions are set and harden system to prevent root privilege escalation opportunities.
Enterprise	T1053	.006	Scheduled Task/Job: Systemd Timers	Restrict read/write access to systemd `.timer` unit files to only select privileged users who have a legitimate need to manage system services.
Enterprise	T1489		Service Stop	Ensure proper process and file permissions are in place to inhibit adversaries from disabling or interfering with critical services.
Enterprise	T1218	.002	Signed Binary Proxy Execution: Control Panel	Restrict storage and execution of Control Panel items to protected directories, such as `C:\Windows`, rather than user directories.
Enterprise	T1553	.003	Subvert Trust Controls: SIP and Trust Provider Hijacking	Restrict storage and execution of SIP DLLs to protected directories, such as C:\Windows, rather than user directories.
Enterprise	T1569		System Services	Ensure that high permission level service binaries cannot be replaced or modified by users with a lower permission level.
		.002	Service Execution	Ensure that high permission level service binaries cannot be replaced or modified by users with a lower permission level.
Enterprise	T1080		Taint Shared Content	Protect shared folders by minimizing users who have write access.
Enterprise	T1552		Unsecured Credentials	Restrict file shares to specific directories with access only to necessary users.
		.001	Credentials In Files	Restrict file shares to specific directories with access only to necessary users.
		.004	Private Keys	Ensure permissions are properly set on folders containing sensitive private keys to prevent unintended access.

References

Mathers, B. (2017, May 31). Windows Time Service Tools and Settings. Retrieved March 26, 2018.
Sander, J. (2017, October 12). Attack Step 3: Persistence with NTFS Extended Attributes – File System Attacks. Retrieved March 21, 2018.

Microsoft. (2018, May 30). Event Tracing. Retrieved September 6, 2018.