CVE-2021-34783 : Security Advisory and Response

A vulnerability in the software-based SSL/TLS message handler of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.

Understanding CVE-2021-34783

This vulnerability affects Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software, potentially leading to a denial of service (DoS) attack.

What is CVE-2021-34783?

The vulnerability arises from insufficient validation of SSL/TLS messages during software-based SSL/TLS decryption, enabling attackers to trigger device reloads by sending crafted SSL/TLS messages.

The Impact of CVE-2021-34783

Exploitation of this vulnerability could result in a denial of service (DoS) condition, causing affected devices to reload and disrupt services.

Technical Details of CVE-2021-34783

This section covers specifics regarding the vulnerability, affected systems and versions, and the mechanism of exploitation.

Vulnerability Description

The flaw originates from inadequate validation of SSL/TLS messages during software-based SSL/TLS decryption.

Affected Systems and Versions

The vulnerability impacts Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software.

Exploitation Mechanism

Remote, unauthenticated attackers can exploit the vulnerability by sending carefully crafted SSL/TLS messages to affected devices, inducing denial of service (DoS) conditions.

Mitigation and Prevention

Here are the steps recommended to mitigate the risks associated with CVE-2021-34783:

Immediate Steps to Take

Employ network-level access controls to restrict access to affected devices.
Monitor network traffic for any unusual SSL/TLS messages.

Long-Term Security Practices

Regularly update and patch affected systems to mitigate known vulnerabilities.
Implement strong encryption protocols and ensure proper SSL/TLS message validation.

Patching and Updates

Refer to the vendor advisory and apply relevant patches to address the vulnerability effectively.