CVE-2019-15239 : Exploit Details and Defense Strategies

A vulnerability in the Linux kernel's net/ipv4/tcp_output.c component, mistakenly backported to earlier long-term kernels, allows a local attacker to trigger use-after-free scenarios, potentially leading to a kernel crash or privilege escalation.

Understanding CVE-2019-15239

What is CVE-2019-15239?

This CVE describes a flaw in the Linux kernel where a backporting error in the net/ipv4/tcp_output.c component introduced a vulnerability that could be exploited by a local attacker.

The Impact of CVE-2019-15239

The vulnerability could result in a kernel crash or privilege escalation when triggered by a local attacker, affecting Linux distributions using specific long-term kernels.

Technical Details of CVE-2019-15239

Vulnerability Description

The issue arises from an incorrect backport of a change in the net/ipv4/tcp_output.c component, allowing a local attacker to exploit use-after-free conditions.

Affected Systems and Versions

Linux distributions using long-term kernels 4.9.x before 4.9.190 or 4.14.x before 4.14.139

Exploitation Mechanism

By adding to a write queue between disconnection and re-connection, a local attacker can trigger use-after-free scenarios.

Mitigation and Prevention

Immediate Steps to Take

Apply patches provided by Linux distributions and kernel updates promptly.
Monitor security advisories for any new information or updates related to this vulnerability.

Long-Term Security Practices

Regularly update the Linux kernel to the latest stable version to mitigate known vulnerabilities.
Implement least privilege access controls to limit the impact of potential privilege escalation.

Patching and Updates

Follow the guidance from Linux distributions and kernel developers on applying patches and updates to address this vulnerability.