CVE-2019-8460 : What You Need to Know
Learn about CVE-2019-8460, a vulnerability in OpenBSD kernel version 6.5 and below that can lead to denial of service. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
OpenBSD kernel version 6.5 and below is susceptible to a vulnerability that allows attackers to trigger extensive TCP SACK holes, leading to denial of service.
Understanding CVE-2019-8460
The vulnerability in the OpenBSD kernel version 6.5 and below can be exploited to cause a denial of service by generating long sequences of TCP SACK holes.
What is CVE-2019-8460?
The OpenBSD kernel, with a version of 6.5 or below, can be compelled to generate extensive sequences of TCP SACK holes. This results in expensive invocations of the tcp_sack_option() function for each incoming SACK packet, posing a risk of denial of service.
The Impact of CVE-2019-8460
Exploiting this vulnerability can result in a denial of service by causing the tcp_sack_option() function to be invoked excessively for each incoming SACK packet.
Technical Details of CVE-2019-8460
The technical details of the CVE-2019-8460 vulnerability are as follows:
Vulnerability Description
The OpenBSD kernel version 6.5 or below can be forced to create long chains of TCP SACK holes, leading to costly calls to tcp_sack_option() for every incoming SACK packet, potentially resulting in denial of service.
Affected Systems and Versions
- Product: OpenBSD
- Vendor: n/a
- Versions Affected: All, including the latest version 6.5
Exploitation Mechanism
Attackers can exploit this vulnerability by sending specially crafted packets to the target system, triggering the creation of extensive TCP SACK holes and causing the tcp_sack_option() function to be invoked repeatedly.
Mitigation and Prevention
To mitigate the CVE-2019-8460 vulnerability, consider the following steps:
Immediate Steps to Take
- Apply the patches provided by OpenBSD to address the vulnerability.
- Monitor network traffic for any signs of exploitation.
- Implement network segmentation to limit the impact of potential attacks.
Long-Term Security Practices
- Keep systems up to date with the latest security patches and updates.
- Conduct regular security assessments and penetration testing to identify and address vulnerabilities.
Patching and Updates
- Regularly check for security advisories from OpenBSD and apply patches promptly to secure the system.