CVE-2022-4069: A deep dive into the Cross-site Scripting (XSS) vulnerability found in librenms/librenms prior to 22.10.

CVE-2022-4069 is a security vulnerability related to Cross-site Scripting (XSS) that was discovered in the librenms/librenms GitHub repository's version prior to 22.10.. In this post, we will explore the details of this vulnerability, analyze a code snippet that exposes the bug, and discuss potential exploits associated with it. We will also provide links to original references for further investigation.

Background on librenms/librenms
LibreNMS is an open source, powerful, and feature-rich auto-discovering PHP-based network monitoring system that uses the SNMP protocol. It is widely used by network administrators to monitor devices, ports, traffic, and other network-related metrics.

Link to the official GitHub repository: https://github.com/librenms/librenms

The Vulnerability: CVE-2022-4069

CVE-2022-4069 is classified as a Cross-site Scripting (XSS) vulnerability. XSS vulnerabilities occur when an attacker is able to inject malicious scripts into web pages viewed by other users. These malicious scripts can steal user data, manipulate web content, or redirect users to malicious sites.

In the case of CVE-2022-4069, the vulnerability exists within the librenms/librenms repository's versions prior to 22.10., and it affects various components of the system. An attacker who successfully exploits this vulnerability can potentially execute arbitrary code in the context of the user's browser or steal sensitive data.

Link to the CVE details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-4069

Code Snippet

The following code snippet demonstrates the potential origin of the vulnerability. The snippet is in PHP and is part of the file html/includes/functions.inc.php:

function generate_device_link($device, $text = null, $vars = array(), $start = , $end = , $from = , $to = )
{
    …

    if (!empty($device['hostname']) && $start > ) {
        $html[] = '<span class="device-time" data-toggle="tooltip" title="' . "From $t_from to $t_to" . '">' . strftime('%e%b%y %H:%M', $start) . '</span>';
    }

    …
}

In this example, the function generate_device_link is used to create links to device pages. However, it does not properly sanitize user-controlled input, which could lead to an XSS vulnerability. Specifically, the '<span class="device-time" data-toggle="tooltip" title="' . "From $t_from to $t_to" . '">' portion of the code may allow an attacker to inject malicious scripts by manipulating the $t_from and $t_to variables.

Possible Exploit

To exploit this vulnerability, an attacker could craft a malicious link that contains an XSS payload designed to target users of the LibreNMS system. For example, the attacker could create a link that includes a malicious script like <img src=x onerror=alert(1)> in the $t_from or $t_to parameters. If the malicious link is clicked by a LibreNMS user, the script is executed, potentially compromising the user's data or security.

Resolution

To address this vulnerability, the librenms/librenms repository released version 22.10., which contains a fix that properly sanitizes user input. It is highly recommended that all users of librenms/librenms update to version 22.10. or later.

Link to the librenms/librenms 22.10. release notes: https://github.com/librenms/librenms/releases/tag/22.10.

Conclusion

Cross-site Scripting (XSS) vulnerabilities, such as the one found in the librenms/librenms repository (CVE-2022-4069), can pose significant security risks to users. To protect against these exploits, it's crucial to follow best practices for securely coding applications, including proper input sanitization and regular security updates.

For additional information related to this vulnerability and for staying up-to-date with the latest security news, refer to the following resources:

- National Vulnerability Database (NVD) entry for CVE-2022-4069: https://nvd.nist.gov/vuln/detail/CVE-2022-4069
- OWASP XSS (Cross Site Scripting) Prevention Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html

Timeline

Published on: 11/20/2022 05:15:00 UTC
Last modified on: 11/21/2022 13:42:00 UTC