In Microsoft DirectX End-User Runtime Web Installer 9.29.1974.0, a low-privilege user can replace an executable file during the installation process, which may result in unintended elevation of privileges. During installation, the installer runs with HIGH integrity and downloads executables and DLLs to the %TEMP% folder - writable by standard users. Subsequently, the installer executes the downloaded executable with HIGH integrity to complete the application installation. However, an attacker can replace the downloaded executable with a malicious, user-controlled executable. When the installer executes this replaced file, it runs the attackers code with HIGH integrity. Since code running at HIGH integrity can escalate to SYSTEM level by registering and executing a service, this creates a complete privilege escalation chain from standard user to SYSTEM. NOTE: The Supplier disputes this record stating that they have determined this to be the behavior as designed.
Weakness
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
Extended Description
Access control involves the use of several protection mechanisms such as:
When any mechanism is not applied or otherwise fails, attackers can compromise the security of the product by gaining privileges, reading sensitive information, executing commands, evading detection, etc. There are two distinct behaviors that can introduce access control weaknesses:
Potential Mitigations
- Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Related Attack Patterns
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