CVE-2021-1376 Explained : Impact and Mitigation

This article provides detailed information about CVE-2021-1376, a vulnerability in Cisco IOS XE Software's fast reload feature that could allow an attacker to execute arbitrary code or install malicious software.

Understanding CVE-2021-1376

CVE-2021-1376 is a high-impact vulnerability in Cisco IOS XE Software that affects several Cisco Catalyst switch series. It allows a local, authenticated attacker to execute code on the underlying operating system, install malicious software, or run unsigned binaries.

What is CVE-2021-1376?

The vulnerability in the fast reload feature of Cisco IOS XE Software can be exploited by an attacker with privileged access to the CLI of the device. This could lead to executing arbitrary code on the system or bypassing image verification checks during the secure boot process.

The Impact of CVE-2021-1376

The CVSS score of 6.7 indicates a medium severity vulnerability with high confidentiality and integrity impacts. The attacker could compromise the availability of the affected devices and gain unauthorized access to execute malicious operations.

Technical Details of CVE-2021-1376

The vulnerability arises due to improper checks in the system boot routines. It affects Cisco IOS XE Software versions running on Cisco Catalyst 3850, Catalyst 9300, and Catalyst 9300L Series Switches.

Vulnerability Description

The fast reload feature allows attackers to exploit the system boot routines' improper checks, leading to unauthorized code execution or installation of malicious software.

Affected Systems and Versions

Cisco IOS XE Software versions running on Catalyst 3850, Catalyst 9300, and Catalyst 9300L Series Switches are impacted by this vulnerability.

Exploitation Mechanism

An authenticated, local attacker with privileged CLI access can exploit this vulnerability to execute arbitrary code, install malicious software, or bypass image verification checks.

Mitigation and Prevention

To address CVE-2021-1376, immediate action is advised alongside long-term security practices and regular patching.

Immediate Steps to Take

Cisco recommends applying software updates provided by the vendor to mitigate the risk of exploitation.

Long-Term Security Practices

Maintaining least privilege access, network segmentation, and continuous monitoring can enhance overall security posture.

Patching and Updates

Regularly check for security advisories from Cisco and apply relevant patches to secure the affected systems.