CVE-2019-3689 : Exploit Details and Defense Strategies

In versions 1.3.0-34.18.1 and earlier of the nfs-utils package for SUSE Linux Enterprise Server 12, and versions 2.1.1-6.10.2 and earlier for SUSE Linux Enterprise Server 15, the ownership of the directory /var/lib/nfs is assigned to statd:nogroup. This directory hosts files that are owned and controlled by the root user. Consequently, if statd is compromised, it can deceive processes operating with root privileges into creating or replacing files in any location within the system.

Understanding CVE-2019-3689

This CVE highlights a vulnerability in the nfs-utils package affecting SUSE Linux Enterprise Server 12 and 15.

What is CVE-2019-3689?

The vulnerability in the nfs-utils package allows an attacker to manipulate files in the system by compromising the statd process, potentially leading to unauthorized access and modifications.

The Impact of CVE-2019-3689

The vulnerability poses a medium severity risk with a CVSS base score of 5.1. The impact includes low availability impact and integrity impact, with no confidentiality impact. The attack complexity is low, and it requires no special privileges.

Technical Details of CVE-2019-3689

The technical aspects of the CVE provide insight into the vulnerability and its implications.

Vulnerability Description

The nfs-utils package in SUSE Linux Enterprise Server 12 and 15 allows the statd process to manipulate root-owned files in the insecure /var/lib/nfs directory, potentially leading to unauthorized system access.

Affected Systems and Versions

SUSE Linux Enterprise Server 12 before and including version 1.3.0-34.18.1
SUSE Linux Enterprise Server 15 before and including version 2.1.1-6.10.2

Exploitation Mechanism

If the statd process is compromised, it can mislead processes with root privileges into creating or overwriting files anywhere in the system, posing a significant security risk.

Mitigation and Prevention

Protecting systems from CVE-2019-3689 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply the latest security updates provided by SUSE to patch the vulnerability promptly.
Monitor system logs for any suspicious activities related to file manipulation.
Restrict network access to vulnerable services to minimize the attack surface.

Long-Term Security Practices

Implement the principle of least privilege to restrict unnecessary access rights.
Conduct regular security audits and vulnerability assessments to identify and address potential risks.
Educate system administrators and users on best security practices to prevent unauthorized access.

Patching and Updates

Regularly check for security advisories from SUSE and apply patches promptly to mitigate the risk of exploitation.