Executive Summary

CVE-2019-25574 is a path traversal vulnerability in Green CMS version 2.x that allows authenticated attackers to download arbitrary files and directories from the server.

Attackers exploit this flaw by manipulating the theme_name parameter in the themeexporthandle action or by supplying base64-encoded file paths to the downfile action. This manipulation bypasses input validation and enables access to sensitive files outside the intended directories.

The vulnerability arises due to improper limitation of pathname to a restricted directory (CWE-22), allowing unauthorized file access.

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Impact Analysis

This vulnerability can lead to unauthorized disclosure of sensitive files and directories on the server hosting Green CMS.

• Attackers can download critical system or application files, potentially exposing configuration files, source code, or other sensitive data.
• Such unauthorized file access can compromise the confidentiality of the system and may aid further attacks.
• Because the vulnerability requires authentication but has low attack complexity and no user interaction, it poses a significant risk to users with valid credentials.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by monitoring for suspicious HTTP GET requests that exploit the path traversal in Green CMS 2.x. Specifically, look for requests targeting the following endpoints with manipulated parameters:'}, {'type': 'list_item', 'content': 'Requests to /index.php with parameters m=admin, c=custom, a=themeexporthandle and a theme_name parameter containing directory traversal sequences such as ../../../'}, {'type': 'list_item', 'content': 'Requests to /index.php with parameters m=admin, c=media, a=downfile and an id parameter containing base64-encoded file paths'}, {'type': 'paragraph', 'content': 'Example commands to detect such attempts using command-line tools like curl or grep on web server logs include:'}, {'type': 'list_item', 'content': "grep -E 'themeexporthandle.*theme_name=.*\\.\\.\\/' /var/log/apache2/access.log"}, {'type': 'list_item', 'content': "grep -E 'downfile.*id=[A-Za-z0-9+/=]+' /var/log/apache2/access.log"}, {'type': 'list_item', 'content': "curl -i 'http://yourserver/index.php?m=admin&c=custom&a=themeexporthandle&theme_name=../../../etc/passwd' to test if the server responds with file content"}, {'type': 'list_item', 'content': "curl -i 'http://yourserver/index.php?m=admin&c=media&a=downfile&id=aW5kZXgucGhw' (where id is base64 for index.php) to check if arbitrary files can be downloaded"}] [1, 3]

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Mitigation Strategies

Immediate mitigation steps include:

• Restrict access to the affected endpoints (/index.php with actions themeexporthandle and downfile) to trusted and authenticated users only.
• Implement strict input validation and sanitization on the theme_name and id parameters to prevent directory traversal sequences and unauthorized base64-decoded file paths.
• Apply the latest patches or updates provided by Green CMS that address this vulnerability.
• Monitor server logs for suspicious requests exploiting this vulnerability and block offending IP addresses if necessary.
• If possible, disable or restrict the functionality related to themeexporthandle and downfile actions until a secure fix is applied.

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