CVE-2021-25316 Explained : Impact and Mitigation

A vulnerability in s390-tools of SUSE Linux Enterprise Server 12-SP5 and SUSE Linux Enterprise Server 15-SP2 could allow local attackers to disrupt VM live migrations.

Understanding CVE-2021-25316

This CVE involves the insecure use of temporary files in s390-tools, impacting SUSE Linux Enterprise Server 12-SP5 and 15-SP2, potentially leading to denial-of-service attacks during VM live migrations.

What is CVE-2021-25316?

CVE-2021-25316 is a Local Denial of Service (DoS) vulnerability that arises from the usage of static temporary files in detach_disks.sh in s390-tools on specific versions of SUSE Linux Enterprise Server.

The Impact of CVE-2021-25316

The vulnerability allows local attackers to disrupt VM live migrations on affected systems, potentially causing denial-of-service situations and impacting the availability of services.

Technical Details of CVE-2021-25316

This section provides detailed technical insights into the vulnerability affecting s390-tools on the specified versions of SUSE Linux Enterprise Server.

Vulnerability Description

The vulnerability is categorized as an Insecure Temporary File issue, identified with CWE-377. It allows local attackers to interfere with VM live migrations, posing a risk of service disruption.

Affected Systems and Versions

Vendor: SUSE
Affected Products:
SUSE Linux Enterprise Server 12-SP5
Vulnerable Version: s390-tools less than 2.1.0-18.29.1
SUSE Linux Enterprise Server 15-SP2
Vulnerable Version: s390-tools less than 2.11.0-9.20.1

Exploitation Mechanism

The exploitation involves local attackers placing malicious static temporary files in the s390-tools directory, disrupting VM live migrations.

Mitigation and Prevention

To address CVE-2021-25316, immediate steps should be taken to secure the affected systems and prevent potential DoS attacks.

Immediate Steps to Take

Update s390-tools to the patched versions: 2.1.0-18.29.1 for SUSE Linux Enterprise Server 12-SP5 and 2.11.0-9.20.1 for SUSE Linux Enterprise Server 15-SP2.
Monitor system logs for any suspicious file activities.

Long-Term Security Practices

Implement proper file permission policies to restrict unauthorized access.
Regularly audit and remove unnecessary temporary files.

Patching and Updates

Stay informed about security updates from SUSE and apply patches promptly to mitigate vulnerabilities.