CVE-2021-41794 : Exploit Details and Defense Strategies

Open5GS 1.0.0 through 2.3.3 suffers from ogs_fqdn_parse vulnerability due to trusting client-supplied length values, resulting in a buffer overflow.

Understanding CVE-2021-41794

This CVE involves a buffer overflow vulnerability in Open5GS that can be exploited through a specific session establishment request.

What is CVE-2021-41794?

Open5GS version 1.0.0 through 2.3.3 is susceptible to a buffer overflow vulnerability in ogs_fqdn_parse.
Attackers can trigger this vulnerability by manipulating the length value, leading to a stack-based buffer overflow.

The Impact of CVE-2021-41794

Allows attackers to execute arbitrary code or crash the application by overwriting memory.
Exploitation can result in a denial of service or possibly remote code execution.

Technical Details of CVE-2021-41794

The specifics of the vulnerability, affected systems, and the exploitation method are detailed below.

Vulnerability Description

The vulnerability occurs in ogs_fqdn_parse due to inadequate validation of client-supplied length, leading to a buffer overflow risk.
An attacker can exploit this by sending a specific PFCP Session Establishment Request.

Affected Systems and Versions

Open5GS versions 1.0.0 through 2.3.3 are impacted by this vulnerability.

Exploitation Mechanism

By supplying a crafted length value in a PFCP Session Establishment Request, the attacker triggers a buffer overflow.
The destination buffer being only 100 bytes long allows the attacker to overwrite adjacent memory.

Mitigation and Prevention

Preventive measures and steps to mitigate the CVE are essential for ensuring system security.

Immediate Steps to Take

Update Open5GS to a patched version that addresses the buffer overflow vulnerability.
Employ network segmentation to limit the exploitability of the vulnerability.

Long-Term Security Practices

Conduct regular security assessments and code reviews to identify and address vulnerabilities.
Implement least privilege access controls to minimize the impact of potential attacks.

Patching and Updates

Monitor official sources for security patches and apply updates promptly to safeguard against known vulnerabilities.