Executive Summary

This vulnerability exists in Webmin versions before 2.640, specifically in the mailboxes component's detachall.cgi script. The issue is that the software does not safely construct a filename when saving an attachment, which can lead to security risks.

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Impact Analysis

Because the filename for saving attachments is not safely constructed, an attacker could potentially exploit this to execute unauthorized actions, such as overwriting files or executing malicious code. This can lead to significant security breaches, including data loss, system compromise, or unauthorized access.

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Compliance Impact

The vulnerability in Webmin before version 2.640 involves unsafe construction of filenames when saving attachments in the mailboxes component, which can lead to risks such as path traversal or script execution attacks.

Such security weaknesses can potentially lead to unauthorized access or manipulation of sensitive data, which may impact compliance with data protection standards and regulations like GDPR and HIPAA that require secure handling and protection of personal and health information.

By allowing malicious attachments to be saved or executed improperly, this vulnerability could result in data breaches or unauthorized disclosure, thereby violating confidentiality and integrity requirements mandated by these regulations.

Therefore, until patched, systems using vulnerable versions of Webmin may face increased risk of non-compliance with common security and privacy standards.

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Detection Guidance

This vulnerability involves unsafe filename construction in the mailboxes component of Webmin before version 2.640, specifically in mailboxes/detachall.cgi. Detection would involve identifying if your system is running a vulnerable version of Webmin (prior to 2.640) and if the mailboxes component is in use.

Since the vulnerability relates to unsafe handling of attachment filenames, you can check the Webmin version installed on your system using commands like:

• webmin --version
• dpkg -l | grep webmin (on Debian-based systems)
• rpm -qa | grep webmin (on RPM-based systems)

Additionally, monitoring HTTP requests to the mailboxes/detachall.cgi endpoint for suspicious or malformed attachment filenames could help detect exploitation attempts, but no specific detection commands or signatures are provided in the available information.

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Mitigation Strategies

The primary mitigation step is to upgrade Webmin to version 2.640 or later, where the vulnerability has been fixed by sanitizing and validating attachment filenames in the mailboxes component.

The fix includes removing dangerous characters from filenames, normalizing path separators, stripping directory paths, and ensuring filenames are safe to prevent path traversal and script execution attacks.

If immediate upgrade is not possible, consider restricting access to the mailboxes/detachall.cgi endpoint and monitoring for suspicious activity related to attachment handling.

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