CVE-2021-42379 : Exploit Details and Defense Strategies

A use-after-free vulnerability in Busybox's awk applet can lead to denial of service and potential code execution.

Understanding CVE-2021-42379

What is CVE-2021-42379?

CVE-2021-42379 is a use-after-free vulnerability in Busybox's awk applet. This vulnerability can be exploited to cause denial of service and potentially execute arbitrary code when processing a maliciously crafted awk pattern in the next_input_file function.

The Impact of CVE-2021-42379

The impact of this vulnerability can range from denial of service to arbitrary code execution, depending on the attacker's intent and the system's configuration.

Technical Details of CVE-2021-42379

Vulnerability Description

The vulnerability arises from improper handling of memory within Busybox's awk applet, specifically in the next_input_file function, leading to a use-after-free condition.

Affected Systems and Versions

Vendor: Busybox
Product: Busybox
Affected Versions:
Version unspecified, up to and excluding 1.34.0

Exploitation Mechanism

The vulnerability can be exploited by an attacker sending a specially crafted awk pattern to trigger the use-after-free condition, potentially leading to a denial of service or code execution.

Mitigation and Prevention

Immediate Steps to Take

Update Busybox to version 1.34.0 or later to patch the vulnerability.
Monitor and restrict network access to affected systems.
Implement strong input validation mechanisms.

Long-Term Security Practices

Regularly update and patch software to address known vulnerabilities.
Conduct security assessments and penetration testing on critical systems.

Patching and Updates

Apply patches provided by Busybox promptly to ensure the remediation of the use-after-free vulnerability.