Adversaries may execute their own malicious payloads by hijacking vulnerable file path references. Adversaries can take advantage of paths that lack surrounding quotations by placing an executable in a higher level directory within the path, so that Windows will choose the adversary's executable to launch.
Service paths (Citation: Microsoft CurrentControlSet Services) and shortcut paths may also be vulnerable to path interception if the path has one or more spaces and is not surrounded by quotation marks (e.g., <code>C:\unsafe path with space\program.exe</code> vs. <code>"C:\safe path with space\program.exe"</code>). (Citation: Help eliminate unquoted path) (stored in Windows Registry keys) An adversary can place an executable in a higher level directory of the path, and Windows will resolve that executable instead of the intended executable. For example, if the path in a shortcut is <code>C:\program files\myapp.exe</code>, an adversary may create a program at <code>C:\program.exe</code> that will be run instead of the intended program. (Citation: Windows Unquoted Services) (Citation: Windows Privilege Escalation Guide)
This technique can be used for persistence if executables are called on a regular basis, as well as privilege escalation if intercepted executables are started by a higher privileged process.
Detection Strategy for Hijack Execution Flow through Path Interception by Unquoted Path
Audit: Auditing is the process of recording activity and systematically reviewing and analyzing the activity and system configurations. The primary purpose of auditing is to detect anomalies and identify potential threats or weaknesses in the environment. Proper auditing configurations can also help to meet compliance requirements. The process of auditing encompasses regular analysis of user behaviors and system logs in support of proactive security measures.
Auditing is applicable to all systems used within an organization, from the front door of a building to accessing a file on a fileserver. It is considered more critical for regulated industries such as, healthcare, finance and government where compliance requirements demand stringent tracking of user and system activates.This mitigation can be implemented through the following measures:
System Audit:
Permission Audits:
Software Audits:
Configuration Audits:
Network Audits:
Execution Prevention: Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions. This mitigation can be implemented through the following measures:
Application Control:
New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.xml")Script Blocking:
Set-ExecutionPolicy AllSigned)Executable Blocking:
%TEMP% or %APPDATA% directories..exe, .bat, or .ps1 files from user-writable directories.Dynamic Analysis Prevention:
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:
Example (Windows): Right-click the shared folder → Properties → Security tab → Adjust permissions for NTFS ACLs.
Harden File Shares:
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):
Audit File System Access:
Restrict Startup Directories:
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.
icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)Flsattr or auditd.