Executive Summary

[{'type': 'paragraph', 'content': "CVE-2025-52998 is a high-severity vulnerability in Chamilo LMS versions up to 1.11.28 caused by insecure deserialization of PHAR (PHP Archive) files. The application deserializes untrusted data, allowing an attacker to create objects of arbitrary classes with fully controlled properties. This enables the attacker to manipulate the web application's logic."}, {'type': 'paragraph', 'content': 'The root cause is insufficient validation against PHAR deserialization attacks. The system originally checked for the prefix "phar://" in file paths in a case-sensitive manner, which could be bypassed using different casing like "pHaR://". Additionally, mime type checks could be circumvented by disguising PHAR archives as image files.'}, {'type': 'paragraph', 'content': 'This vulnerability was patched in version 1.11.30 by improving case-insensitive detection of PHAR file paths and enhancing error handling to prevent processing of PHAR files.'}] [2, 1]

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Impact Analysis

Exploitation of this vulnerability can allow an attacker with high privileges to remotely manipulate the Chamilo LMS web application logic by creating arbitrary objects during deserialization.

Potential impacts include dangerous actions such as file deletion, file movement, or arbitrary code execution on the server hosting the application.

The attack requires no user interaction and has low complexity, but does require high privileges.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability involves insecure PHAR deserialization in Chamilo LMS versions prior to 1.11.30, which can be exploited by sending specially crafted PHAR files or requests that include PHAR streams with varying case prefixes such as "phar://" or "pHaR://".'}, {'type': 'paragraph', 'content': 'To detect exploitation attempts or presence of this vulnerability on your system or network, you can monitor for unusual file system operations involving PHAR streams or suspicious file names that might disguise PHAR archives (e.g., files with image extensions like .jpg but containing PHAR payloads).'}, {'type': 'paragraph', 'content': 'Since the vulnerability is related to PHP deserialization and file path handling, you can also check your Chamilo LMS installation version to confirm if it is older than 1.11.30.'}, {'type': 'list_item', 'content': 'Check Chamilo LMS version: Run a command or check the application interface to verify the version is 1.11.30 or later.'}, {'type': 'list_item', 'content': "Search for PHAR files or suspicious uploads in the Chamilo directories, for example: `find /path/to/chamilo -type f -iname '*.phar'` or files with image extensions that might be disguised PHAR archives."}, {'type': 'list_item', 'content': 'Monitor web server logs for requests containing "phar://" or case variations like "pHaR://" in parameters or file paths.'}, {'type': 'list_item', 'content': 'Use PHP error logs or application logs to detect error messages related to PHAR file handling or deserialization issues.'}] [1, 2]

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Mitigation Strategies

The primary mitigation step is to upgrade Chamilo LMS to version 1.11.30 or later, where this vulnerability has been patched.

If upgrading immediately is not possible, avoid enabling the vChamilo plugin, as it is not enabled by default and is a recommended workaround to reduce exposure.

Ensure that file path validation for PHAR streams is case-insensitive and that the application properly rejects PHAR files regardless of case variations in the prefix.

Review and restrict file upload functionality to prevent uploading of PHAR archives or disguised PHAR files.

Monitor and audit file system permissions and PHP deserialization usage to limit the impact of potential exploitation.

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