Executive Summary

The vulnerability exists in the ci4ms Theme::upload function in versions prior to 0.31.5.0. It is a Zip Slip path traversal flaw that allows an authenticated backend user with theme creation permissions to upload specially crafted ZIP archives. These ZIP files contain entries with directory traversal sequences that bypass validation and extract files outside the intended directory.

This flaw enables the attacker to write files to arbitrary locations on the filesystem, including the public web root, allowing them to drop malicious PHP files and achieve remote code execution (RCE). The root cause is the lack of validation on ZIP entry names before extraction.

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Compliance Impact

This vulnerability allows an authenticated backend user with theme create permission to achieve remote code execution by uploading malicious ZIP archives that write files to arbitrary filesystem locations, including the public web root.

Such a compromise can lead to full server control, including access to sensitive data such as database credentials stored in configuration files.

This level of unauthorized access and potential data exposure can result in violations of data protection regulations like GDPR and HIPAA, which require strict controls over personal and sensitive data.

Organizations using vulnerable versions prior to 0.31.5.0 risk non-compliance due to possible data breaches, unauthorized data access, and loss of data integrity and availability.

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Impact Analysis

Exploiting this vulnerability can lead to full server compromise. An attacker can upload a PHP shell to the public web root, enabling remote code execution.

• Complete control over the server hosting the application.
• Access to sensitive data such as database credentials stored in configuration files like .env.
• Ability to modify or delete site content, potentially defacing the website or injecting malicious content.
• Severe impacts on confidentiality, integrity, and availability of the system.

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Detection Guidance

This vulnerability can be detected by checking for the presence of unauthorized PHP files uploaded via the Theme upload functionality, especially those placed outside the intended directories such as under the public web root.

Since the vulnerability involves ZIP archive extraction without validating entry names, you can look for suspicious ZIP files uploaded by authenticated users with theme creation permissions.

To detect exploitation attempts or presence of malicious files, you can run commands to find recently created or modified PHP files in web-accessible directories. For example:

• find /path/to/ci4ms/public -name '*.php' -mtime -7 -ls
• grep -r 'shell' /path/to/ci4ms/public

Additionally, monitoring web server logs for unusual requests to newly uploaded PHP files or unexpected URLs can help detect exploitation.

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Mitigation Strategies

The immediate and most effective mitigation step is to upgrade the ci4ms installation to version 0.31.5.0 or later, where this vulnerability has been patched.

Until the upgrade can be performed, restrict or disable the theme creation permission for authenticated backend users to prevent exploitation.

Review and remove any suspicious PHP files that may have been uploaded via the vulnerable Theme::upload function.

Implement monitoring of file uploads and web server logs to detect any attempts to exploit this vulnerability.

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