CVE-2018-5721 Explained : Impact and Mitigation

A stack-based buffer overflow vulnerability in ASUS routers using software from https://github.com/RMerl/asuswrt-merlin allows authenticated attackers to execute arbitrary code by manipulating a specific setting.

Understanding CVE-2018-5721

This CVE involves a critical security issue in ASUS routers that could lead to unauthorized code execution.

What is CVE-2018-5721?

The vulnerability arises from inadequate validation of the variable action_script's length in the ej_update_variables function, enabling attackers to trigger a stack-based buffer overflow.

The Impact of CVE-2018-5721

Exploitation of this vulnerability by authenticated attackers can result in the execution of arbitrary code, potentially compromising the router's security and allowing for unauthorized access.

Technical Details of CVE-2018-5721

This section delves into the specifics of the vulnerability.

Vulnerability Description

The flaw in the ej_update_variables function of ASUS routers allows attackers to exploit a stack-based buffer overflow by manipulating the action_script variable.

Affected Systems and Versions

Product: ASUS routers
Vendor: ASUS
Versions: All versions using software from https://github.com/RMerl/asuswrt-merlin

Exploitation Mechanism

Attackers authenticated on the web can send a request to update a specific setting, triggering the buffer overflow by manipulating the action_script variable.

Mitigation and Prevention

Protecting systems from CVE-2018-5721 requires immediate action and long-term security measures.

Immediate Steps to Take

Disable remote access to the router's web interface if not required
Regularly monitor ASUS security advisories for patches and updates

Long-Term Security Practices

Implement strong, unique passwords for router access
Regularly update router firmware to the latest version

Patching and Updates

Apply patches and firmware updates provided by ASUS to address the vulnerability