CVE-2021-37159 : Exploit Details and Defense Strategies

This CVE-2021-37159 article provides insights into a vulnerability in the Linux kernel that could result in a use-after-free and double free due to a flaw in the hso_free_net_device function call in drivers/net/usb/hso.c.

Understanding CVE-2021-37159

This section delves deeper into the impact and technical details of the CVE-2021-37159 vulnerability.

What is CVE-2021-37159?

The CVE-2021-37159 vulnerability exists in the Linux kernel through version 5.13.4. The issue arises from the hso_free_net_device function in drivers/net/usb/hso.c, which calls unregister_netdev without verifying the NETREG_REGISTERED state. This oversight can lead to a use-after-free and double free scenario.

The Impact of CVE-2021-37159

If exploited, this vulnerability can allow an attacker to trigger a use-after-free condition and potentially execute arbitrary code within the context of the kernel. This could result in a denial of service (DoS) or privilege escalation.

Technical Details of CVE-2021-37159

Let's explore the specific technical aspects of CVE-2021-37159, including the vulnerability description, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

The issue stems from the improper handling of resource deallocation in the hso_free_net_device function, which can lead to memory corruption and subsequent exploitation.

Affected Systems and Versions

The CVE-2021-37159 vulnerability impacts the Linux kernel up to version 5.13.4. Systems running these versions are at risk of the use-after-free and double free conditions.

Exploitation Mechanism

To exploit this vulnerability, an attacker would need to craft a malicious payload and send it to a vulnerable system, triggering the flawed function call in drivers/net/usb/hso.c and potentially gaining unauthorized access.

Mitigation and Prevention

In this section, we outline immediate steps to take to secure systems, recommend long-term security practices, and emphasize the importance of patching and updates.

Immediate Steps to Take

System administrators should apply security patches provided by the Linux kernel maintainers promptly to address CVE-2021-37159. Additionally, monitoring for any signs of exploitation is crucial.

Long-Term Security Practices

To enhance overall system security, it is advisable to follow security best practices such as regular security audits, threat intelligence analysis, and proactive vulnerability management.

Patching and Updates

Regularly updating the Linux kernel to the latest patches and versions is essential to ensure that known vulnerabilities like CVE-2021-37159 are mitigated effectively.