CVE-2019-1836 Explained : Impact and Mitigation

A weakness has been identified in the system shell used by Cisco Nexus 9000 Series Fabric Switches operating in Application Centric Infrastructure (ACI) mode, allowing a local attacker to manipulate symbolic links and overwrite critical system files.

Understanding CVE-2019-1836

What is CVE-2019-1836?

The vulnerability in Cisco Nexus 9000 Series Fabric Switches ACI Mode allows authenticated local attackers to overwrite sensitive system files by exploiting symbolic links.

The Impact of CVE-2019-1836

The vulnerability could lead to unauthorized access and manipulation of critical system files, potentially compromising sensitive information.

Technical Details of CVE-2019-1836

Vulnerability Description

The vulnerability arises from the system shell's failure to appropriately verify symbolic link paths within directory structures.

Affected Systems and Versions

Cisco NX-OS Software for Nexus 9000 Series Fabric Switches ACI Mode versions less than 14.1(1i) are affected.

Exploitation Mechanism

Attackers with legitimate device credentials can input crafted instructions using symbolic link CLI commands to exploit the vulnerability.

Mitigation and Prevention

Immediate Steps to Take

Update to the latest software version, 14.1(1i), to address and mitigate the vulnerability.

Long-Term Security Practices

Implement strict access controls and regularly monitor system files for unauthorized changes.
Conduct security training to educate users on the risks of symbolic link manipulation.

Patching and Updates

Regularly apply security patches and updates provided by Cisco to ensure system security.