Executive Summary

This vulnerability in ImpressCMS 1.4.4 is a file upload weakness caused by insufficient sanitization of file extensions. Attackers can bypass file upload restrictions by using alternative PHP-related file extensions such as .php2, .php6, .php7, .phps, and .pht. This allows them to upload malicious files that can execute arbitrary PHP code on the server, potentially leading to remote code execution. [2, 3]

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Impact Analysis

The vulnerability can have severe impacts including unauthorized remote code execution on the server hosting ImpressCMS. This can lead to full compromise of the server, allowing attackers to access, modify, or delete sensitive data, disrupt service availability, and potentially use the server as a foothold for further attacks. [2, 3]

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Detection Guidance

You can detect this vulnerability by scanning your ImpressCMS installation for uploaded files with suspicious alternative PHP extensions such as .php2, .php6, .php7, .phps, and .pht. On the server, you can use commands like `find /path/to/impresscms/uploads -type f \( -name '*.php2' -o -name '*.php6' -o -name '*.php7' -o -name '*.phps' -o -name '*.pht' \)` to locate potentially malicious files. Additionally, monitoring web server logs for requests to files with these extensions may help identify exploitation attempts. [2, 3]

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Mitigation Strategies

Immediate mitigation steps include restricting or disabling file uploads until a patch or update is applied. You should implement a whitelist approach for allowed file extensions instead of relying on blacklists, blocking all extensions except those explicitly permitted. Additionally, review and remove any suspicious files with alternative PHP extensions from your server. Applying any available security updates or patches from ImpressCMS is also critical to address this vulnerability. [2, 3]

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