CVE-2021-34749 : Exploit Details and Defense Strategies

A vulnerability in Server Name Identification (SNI) request filtering of Cisco Web Security Appliance (WSA), Cisco Firepower Threat Defense (FTD), and the Snort detection engine could allow an unauthenticated, remote attacker to bypass filtering technology on an affected device and exfiltrate data from a compromised host. This vulnerability is due to inadequate filtering of the SSL handshake. An attacker could exploit this vulnerability by using data from the SSL client hello packet to communicate with an external server. A successful exploit could allow the attacker to execute a command-and-control attack on a compromised host and perform additional data exfiltration attacks.

Understanding CVE-2021-34749

This section delves into the details of the CVE-2021-34749 vulnerability.

What is CVE-2021-34749?

The CVE-2021-34749 vulnerability involves Server Name Identification (SNI) request filtering of certain Cisco products, allowing remote attackers to bypass filtering mechanisms and exfiltrate data from compromised hosts.

The Impact of CVE-2021-34749

The impact of this vulnerability includes the potential for unauthorized data exfiltration and the execution of command-and-control attacks on vulnerable hosts.

Technical Details of CVE-2021-34749

Explore the technical specifics of the CVE-2021-34749 vulnerability.

Vulnerability Description

The vulnerability arises from insufficient SSL handshake filtering, enabling attackers to use SSL client hello packet data to communicate externally and compromise data.

Affected Systems and Versions

The vulnerability affects Cisco Web Security Appliance (WSA) and specific versions of the product.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating SSL client hello packet data to communicate with external servers and initiate data exfiltration activities.

Mitigation and Prevention

Discover the steps to mitigate and prevent exploitation of CVE-2021-34749.

Immediate Steps to Take

Immediately update affected Cisco products to the patched versions and review firewall configurations to restrict unauthorized data exfiltration.

Long-Term Security Practices

Implement network segmentation, strong firewall rules, and regular security updates to enhance overall system security.

Patching and Updates

Regularly monitor vendor advisories for security updates, apply patches promptly, and conduct security assessments to identify and address vulnerabilities proactively.