CVE-2021-4024 : Exploit Details and Defense Strategies

A flaw was found in podman that affects version 3.4.3. The vulnerability allows an attacker to potentially forward ports from the host to a virtual machine, making private services accessible to the network, and even interrupt the host's services.

Understanding CVE-2021-4024

This CVE pertains to a security flaw in the

podman

container management tool, specifically related to the

podman machine

function and the

gvproxy

process it spawns on the host system.

What is CVE-2021-4024?

The vulnerability in podman allows an attacker to use the

gvproxy

API to forward ports from the host to a virtual machine, thereby exposing private services on the VM to the network and potentially disrupting the host's services as well.

The Impact of CVE-2021-4024

Exploitation of this vulnerability could lead to unauthorized access to private services on the virtual machine and disruption of services on the host system due to port forwarding.

Technical Details of CVE-2021-4024

This section delves into the specifics of the vulnerability.

Vulnerability Description

The flaw in podman arises from the

podman machine

function spawning a

gvproxy

process on the host, which exposes the

gvproxy

API on port 7777, potentially enabling attackers to forward ports between the host and the VM.

Affected Systems and Versions

Podman version 3.4.3 is confirmed to be affected by this vulnerability.

Exploitation Mechanism

By leveraging the exposed

gvproxy

API on port 7777, threat actors can manipulate port forwarding between the host and the VM, compromising the security of private services.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-4024, consider the following measures.

Immediate Steps to Take

Update podman to version 3.4.3 or later to address the vulnerability.
Ensure that unnecessary ports are closed on the host system to minimize attack surface.

Long-Term Security Practices

Regularly monitor for security advisories and updates related to podman to stay informed about potential vulnerabilities.
Implement network segmentation to restrict access between host systems and virtual machines.

Patching and Updates

Stay informed about the latest patches and updates for podman to promptly address any security issues and ensure the protection of your systems.