CVE-2018-17159 : Exploit Details and Defense Strategies

CVE-2018-17159 was published on December 4, 2018, and affects FreeBSD versions before 11.2-RELEASE-p5. The vulnerability in the NFS server allows unprivileged remote users to cause resource exhaustion by exploiting a lack of bounds checking in the READDIRPLUS NFS request.

Understanding CVE-2018-17159

This CVE identifies a critical vulnerability in FreeBSD's NFS server that can be exploited by remote attackers to exhaust server resources.

What is CVE-2018-17159?

The vulnerability in the READDIRPLUS NFS request in FreeBSD versions before 11.2-RELEASE-p5 allows unprivileged remote users to trigger resource exhaustion by forcing the server to allocate memory of any size.

The Impact of CVE-2018-17159

Exploiting this vulnerability can lead to resource exhaustion on the NFS server, potentially causing denial of service (DoS) conditions and disrupting server operations.

Technical Details of CVE-2018-17159

This section delves into the technical aspects of the vulnerability.

Vulnerability Description

The vulnerability arises from the lack of bounds checking in the READDIRPLUS NFS request, enabling unprivileged remote users to exhaust server resources.

Affected Systems and Versions

Product: FreeBSD
Vendor: FreeBSD
Versions Affected: FreeBSD 11.2 before 11.2-RELEASE-p5

Exploitation Mechanism

By manipulating the READDIRPLUS NFS request, attackers can force the NFS server to allocate memory of any size, leading to resource exhaustion.

Mitigation and Prevention

Protecting systems from CVE-2018-17159 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply the necessary patches provided by FreeBSD to address the vulnerability.
Restrict network access to the NFS server to trusted entities only.
Monitor server resources for unusual consumption that may indicate exploitation.

Long-Term Security Practices

Regularly update and patch FreeBSD systems to mitigate known vulnerabilities.
Implement network segmentation to isolate critical servers like NFS from untrusted networks.
Conduct regular security audits and penetration testing to identify and address potential weaknesses.

Patching and Updates

Ensure timely installation of security patches released by FreeBSD to remediate the vulnerability and enhance system security.