CVE-2019-1687 : Vulnerability Insights and Analysis

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software TCP Proxy Denial of Service Vulnerability

Understanding CVE-2019-1687

A vulnerability in the TCP proxy feature for Cisco ASA Software and Cisco FTD Software could lead to a denial of service (DoS) attack.

What is CVE-2019-1687?

The flaw in the TCP proxy feature of Cisco ASA Software and FTD Software allows a remote attacker to trigger an unexpected device restart, causing a DoS situation. The vulnerability arises from errors in TCP packet inspection, resulting in an incorrect Layer 2 header format.

The Impact of CVE-2019-1687

Attack Complexity: High
Attack Vector: Network
Availability Impact: High
Base Score: 6.8 (Medium Severity)
Scope: Changed
Vector String: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H

Technical Details of CVE-2019-1687

The technical aspects of the vulnerability are as follows:

Vulnerability Description

The flaw allows an unauthorized attacker to exploit TCP proxy functionality, causing a device restart and potential DoS.

Affected Systems and Versions

Cisco ASA Software versions less than 9.4.4.34, 9.8.4, and 9.9.2.50 are affected.

Exploitation Mechanism

An attacker needs to send a specific sequence of TCP packets to the target device to exploit the vulnerability.

Mitigation and Prevention

Steps to address and prevent the CVE-2019-1687 vulnerability:

Immediate Steps to Take

Apply vendor-released patches promptly.
Monitor network traffic for any suspicious activity.

Long-Term Security Practices

Regularly update and patch all software and firmware.
Implement network segmentation and access controls.

Patching and Updates

Cisco has provided patches to address the vulnerability. Ensure timely installation of these patches to mitigate the risk.