CVE-2023-20256 Explained : Impact and Mitigation

Multiple vulnerabilities in the per-user-override feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software have been identified, potentially allowing an unauthenticated, remote attacker to bypass configured access control lists (ACLs) and permit unauthorized traffic flow through the affected devices.

Understanding CVE-2023-20256

These vulnerabilities are a result of a logic error in the affected software when constructing and applying per-user-override rules. By exploiting these vulnerabilities, an attacker could bypass the interface ACL and gain access to protected resources.

What is CVE-2023-20256?

CVE-2023-20256 involves multiple vulnerabilities in Cisco ASA Software and Cisco FTD Software that could be exploited by an attacker to bypass ACL configurations and allow unauthorized traffic to flow through affected devices.

The Impact of CVE-2023-20256

The successful exploitation of CVE-2023-20256 could lead to unauthorized access to resources that should be protected, potentially compromising the security of the affected systems and data.

Technical Details of CVE-2023-20256

These technical details provide insights into the vulnerability, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerabilities in the per-user-override feature of Cisco ASA Software and Cisco FTD Software are attributed to a logic error in the software's handling of per-user-override rules, enabling unauthorized traffic to bypass configured ACLs.

Affected Systems and Versions

Numerous versions of Cisco ASA Software and Cisco FTD Software are impacted by CVE-2023-20256. Refer to the vendor's advisory for a comprehensive list of affected versions.

Exploitation Mechanism

An attacker can exploit these vulnerabilities by connecting to a network through an affected device with a vulnerable configuration, circumventing ACLs to gain unauthorized access to protected resources.

Mitigation and Prevention

Understanding how to mitigate and prevent the exploitation of CVE-2023-20256 is crucial for ensuring the security of affected systems.

Immediate Steps to Take

Immediately review and update ACL configurations on affected Cisco ASA and FTD devices to mitigate the risk of unauthorized traffic flow. Monitor for any suspicious activity that could indicate exploitation attempts.

Long-Term Security Practices

Implement comprehensive security measures, such as network segmentation, regular security audits, and user access controls, to enhance the overall security posture and prevent similar vulnerabilities in the future.

Patching and Updates

Stay informed about security advisories from Cisco and promptly apply patches and updates provided by the vendor to address CVE-2023-20256 and enhance the security of your network infrastructure.