CVE-2017-6766 Explained : Impact and Mitigation

A weakness has been identified in Cisco Firepower System Software versions 5.4.0, 5.4.1, 6.0.0, 6.1.0, 6.2.0, 6.2.1, and 6.2.2, specifically in the Secure Sockets Layer (SSL) Decryption and Inspection feature. This vulnerability allows unauthorized remote attackers to bypass SSL policies, potentially compromising system security.

Understanding CVE-2017-6766

This CVE pertains to a critical vulnerability in Cisco Firepower System Software that affects SSL Decryption and Inspection functionality.

What is CVE-2017-6766?

The vulnerability in Cisco Firepower System Software versions 5.4.0 to 6.2.2 enables attackers to circumvent SSL decryption and inspection policies, allowing unmonitored traffic to pass through the system.

The Impact of CVE-2017-6766

The vulnerability poses a significant risk as it permits unauthorized remote attackers to evade SSL policies designed for decrypting and inspecting traffic on affected systems. By exploiting this flaw, attackers can bypass security measures, potentially leading to data breaches or unauthorized access.

Technical Details of CVE-2017-6766

This section provides detailed technical insights into the vulnerability.

Vulnerability Description

The flaw arises from an unexpected interaction involving Known Key and Decrypt and Resign configuration settings of SSL policies when the affected software receives unexpected SSL packet headers. Attackers can exploit this by sending crafted SSL packets through affected devices in valid SSL sessions.

Affected Systems and Versions

Cisco Firepower System Software versions 5.4.0, 5.4.1, 6.0.0, 6.1.0, 6.2.0, 6.2.1, and 6.2.2

Exploitation Mechanism

Attackers send specifically crafted SSL packets through affected devices in valid SSL sessions
Successful exploitation allows bypassing SSL decryption and inspection policies

Mitigation and Prevention

Protecting systems from CVE-2017-6766 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply vendor-supplied patches and updates promptly
Monitor network traffic for any suspicious activity
Implement additional security measures such as network segmentation

Long-Term Security Practices

Regularly update and patch software and firmware
Conduct security audits and assessments periodically
Educate users and IT staff on cybersecurity best practices

Patching and Updates

Cisco has released patches to address this vulnerability
Ensure all affected systems are updated with the latest security fixes