CVE-2017-3793 : Security Advisory and Response
Learn about CVE-2017-3793, a vulnerability in Cisco ASA Software and Cisco FTD Software that could lead to a denial of service (DoS) condition by exhausting the global out-of-order TCP queue. Find mitigation steps and patching information here.
A vulnerability in the TCP normalizer of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition by exhausting the global out-of-order TCP queue.
Understanding CVE-2017-3793
This CVE involves a flaw in the TCP normalizer of Cisco ASA Software and Cisco FTD Software, potentially leading to a DoS condition.
What is CVE-2017-3793?
The vulnerability allows an attacker to exhaust the global out-of-order TCP queue by initiating numerous unique permitted TCP connections with out-of-order segments, resulting in a DoS condition.
The Impact of CVE-2017-3793
- Denial of service (DoS) condition on Cisco ASA and FTD, causing rejection of incoming traffic on all interfaces.
Technical Details of CVE-2017-3793
This section provides more technical insights into the vulnerability.
Vulnerability Description
The flaw arises from inadequate limitations on the global out-of-order TCP queue for specific block sizes, allowing attackers to exhaust available blocks and trigger a DoS condition.
Affected Systems and Versions
- Cisco ASA Software versions 8.0 to 8.7 and 9.0 to 9.6
- Cisco Firepower Threat Defense (FTD) Software
Exploitation Mechanism
- Attacker initiates numerous unique permitted TCP connections with out-of-order segments to exhaust the global out-of-order TCP queue.
Mitigation and Prevention
Protecting systems from CVE-2017-3793 requires immediate actions and long-term security practices.
Immediate Steps to Take
- Apply vendor-supplied patches and updates promptly.
- Monitor network traffic for any signs of exploitation.
- Implement network segmentation to limit the impact of potential attacks.
Long-Term Security Practices
- Regularly update and patch all software and firmware.
- Conduct security assessments and penetration testing to identify vulnerabilities.
- Educate users and administrators on best security practices.
- Implement intrusion detection and prevention systems.
Patching and Updates
- Cisco has released patches to address the vulnerability. Ensure all affected systems are updated with the latest security fixes.