CVE-2020-3191 Explained : Impact and Mitigation

A vulnerability in DNS over IPv6 packet processing for Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition by triggering the device to reload unexpectedly.

Understanding CVE-2020-3191

This CVE involves a specific vulnerability in Cisco ASA and FTD Software related to DNS over IPv6 packet processing.

What is CVE-2020-3191?

The vulnerability stems from improper length validation of a field in an IPv6 DNS packet, enabling an attacker to exploit it by sending a crafted DNS query over IPv6, leading to a device reload and subsequent DoS condition.

The Impact of CVE-2020-3191

CVSS Base Score: 8.6 (High Severity)
Attack Vector: Network
Availability Impact: High
The vulnerability could result in a DoS condition, affecting the availability of the device.

Technical Details of CVE-2020-3191

This section delves into the technical aspects of the vulnerability.

Vulnerability Description

The vulnerability arises from improper length validation of a field in an IPv6 DNS packet, allowing an attacker to trigger a device reload and cause a DoS condition.

Affected Systems and Versions

Affected Product: Cisco Adaptive Security Appliance (ASA) Software
Vendor: Cisco
Affected Version: Not Applicable (n/a)

Exploitation Mechanism

Attackers can exploit this vulnerability by sending a crafted DNS query over IPv6, traversing the affected device and causing it to reload, resulting in a DoS condition.

Mitigation and Prevention

Protecting systems from CVE-2020-3191 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply vendor-provided patches or updates promptly.
Implement network segmentation to limit the impact of potential attacks.
Monitor network traffic for any suspicious DNS over IPv6 packets.

Long-Term Security Practices

Regularly update and patch all software and firmware to address known vulnerabilities.
Conduct security training for employees to raise awareness of potential threats.

Patching and Updates

Cisco may release patches or updates to address this vulnerability. Stay informed through official advisories and apply patches as soon as they are available.