Executive Summary

This vulnerability occurs in TYPO3 CMS where backend users with access to the Form Framework could upload and use files as form definitions even if those files did not have the required .form.yaml extension.

Because the system did not properly enforce the file extension check, maliciously crafted form definition files could be processed, allowing attackers to execute arbitrary SQL statements.

This SQL execution capability enables attackers to escalate their privileges by creating administrative backend user accounts, compromising the system's security.

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Impact Analysis

If exploited, this vulnerability allows an attacker with backend access to escalate their privileges by executing arbitrary SQL commands.

Specifically, attackers can create administrative backend user accounts, gaining full control over the TYPO3 CMS installation.

This can lead to unauthorized access, data manipulation, and potentially full compromise of the affected system.

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Detection Guidance

This vulnerability involves backend users uploading and using files with incorrect extensions (not ending in .form.yaml) as form definitions in TYPO3 CMS. Detection involves identifying such improperly named form definition files within the system.

You can detect potentially malicious files by searching the TYPO3 installation directories for form definition files that do not end with the required .form.yaml extension.

• Use a command like: find /path/to/typo3/ -type f ! -name '*.form.yaml' -exec grep -l 'form definition' {} + to locate files that might be used as form definitions but have incorrect extensions.
• Check backend user activity logs for uploads or modifications of files with suspicious extensions.

Since the vulnerability allows execution of arbitrary SQL via malicious form files, monitoring database logs for unusual administrative user creation or privilege escalations can also help detect exploitation.

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Mitigation Strategies

The primary mitigation step is to update TYPO3 CMS to a patched version where this vulnerability is fixed.

• Upgrade to TYPO3 CMS versions 10.4.57 ELTS, 11.5.51 ELTS, 12.4.46 ELTS, 13.4.31 LTS, or 14.3.3 LTS or later.

These updates enforce strict validation of form definition files, ensuring only files ending with .form.yaml are accepted, preventing malicious files from being processed.

Additionally, follow the TYPO3 Security Guide and subscribe to the typo3-announce mailing list for ongoing security updates and best practices.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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