CVE-2021-28831 Explained : Impact and Mitigation

A vulnerability has been discovered in BusyBox through version 1.32.1, tracked as CVE-2021-28831. The flaw in decompress_gunzip.c can lead to an invalid free or segmentation fault due to mishandling the error bit on the huft_build result pointer when processing malformed gzip data.

Understanding CVE-2021-28831

This section delves into the details of the CVE-2021-28831 vulnerability, its impact, technical aspects, and mitigation strategies.

What is CVE-2021-28831?

decompress_gunzip.c in BusyBox through 1.32.1 mishandles the error bit on the huft_build result pointer, with a resultant invalid free or segmentation fault, via malformed gzip data.

The Impact of CVE-2021-28831

The vulnerability has a CVSS base score of 7.5, indicating a high severity issue with a potential for network-based attacks causing availability impact, but with no impact on confidentiality or integrity. It does not require privileges for exploitation.

Technical Details of CVE-2021-28831

This section provides more insights into the technical aspects of CVE-2021-28831.

Vulnerability Description

The vulnerability arises from the mishandling of the error bit on the huft_build result pointer in decompress_gunzip.c, allowing for an invalid free or segmentation fault when processing malformed gzip data.

Affected Systems and Versions

All versions of BusyBox through 1.32.1 are affected by this vulnerability.

Exploitation Mechanism

The vulnerability can be exploited by an attacker sending specially crafted malformed gzip data to the target system, triggering the invalid free or segmentation fault.

Mitigation and Prevention

It is crucial to take immediate steps to protect systems and implement long-term security practices to prevent such vulnerabilities in the future.

Immediate Steps to Take

Update BusyBox to version 1.32.2 or apply patches provided by vendors to mitigate the vulnerability. Organizations should also monitor for any signs of exploitation.

Long-Term Security Practices

Regularly update software and implement security best practices to enhance the overall security posture of the system.

Patching and Updates

Stay informed about security updates from vendors and promptly apply patches to address known vulnerabilities.