CVE-2019-1756 Explained : Impact and Mitigation

Cisco IOS XE Software Command Injection Vulnerability

Understanding CVE-2019-1756

This CVE involves a flaw in Cisco IOS XE Software that allows an authenticated remote attacker to execute commands with root privileges on the device's Linux shell.

What is CVE-2019-1756?

The vulnerability arises from inadequate filtering of user input, enabling an attacker with valid administrator access to input a malicious payload via the web UI. By sending a request to a specific web UI endpoint, the attacker can run arbitrary commands as the root user, leading to a complete system compromise.

The Impact of CVE-2019-1756

The vulnerability has a CVSS base score of 7.2, indicating a high severity level. It poses a significant risk to confidentiality, integrity, and availability, with a low attack complexity but requiring high privileges.

Technical Details of CVE-2019-1756

Vulnerability Description

The flaw in Cisco IOS XE Software allows an authenticated attacker to execute commands on the device's Linux shell with root privileges due to improper input filtering.

Affected Systems and Versions

Cisco IOS XE Software versions 3.2.0JA, 16.7.1, 16.7.1a, 16.7.1b, 16.7.2, 16.7.3, 16.8.1, 16.8.1a, 16.8.1b, 16.8.1s, 16.8.1c, 16.8.1d, 16.8.2, 16.8.1e are impacted.

Exploitation Mechanism

Attacker with valid admin access inputs a username with a malicious payload in the web UI.
Request is made to a specific endpoint in the web UI to execute arbitrary commands as the root user.

Mitigation and Prevention

Immediate Steps to Take

Apply vendor-provided patches and updates promptly.
Restrict access to the web UI and ensure strong, unique passwords for admin accounts.
Monitor and analyze network traffic for any suspicious activities.

Long-Term Security Practices

Regularly update and patch all software and firmware on network devices.
Conduct security training for administrators on best practices and security protocols.

Patching and Updates

Cisco has released patches to address this vulnerability. Ensure timely application of these patches to secure affected systems.