File Upload Bypass Vulnerability in upload_handle.php with POC and Mitigation

Vulnerability Overview This vulnerability relates to the file upload functionality, specifically within the file. An attacker can bypass file type checks by crafting specific requests to upload malicious files. Impact Scope Affected File: Affected Functionality: File upload functionality Potential Risk: Attackers may upload malicious scripts, potentially leading to server compromise or data leakage. Remediation Plan 1. Strict File Type Validation: Strictly check file extensions and MIME types during upload, ensuring only expected file types are permitted. 2. File Content Verification: Further validate the content of uploaded files to ensure they conform to the expected format. 3. Storage Path Control: Store uploaded files in non-web-accessible directories to prevent direct execution. 4. Permission Control: Restrict execution permissions on uploaded files to prevent them from being executed directly. POC Code ```php <?php ini_set('max_file_uploads', 1); define('MAX_FILENAME_LENGTH', 255); include(CONFIG['SERVER_ROOT'] . '/classes/file_checker.class.php'); enforce_login(); $file = $_FILES['file_input']; // This is our torrent file $subtitleName = $file['tmp_name']; $name = $file['name']; $subtitleFormat = get_file_extension($name); $ALLOWEDFormat = array("rar", "zip", "7z", "tar", "gz", "bz2", "xz", "lha", "lzh", "lzo", "lzma", "rar", "zip", "tar", "tgz", "tar.gz", "tar.bz2", "tar.xz", "tar.lz", "tar.lzma", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "tar.7z", "

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File Upload Bypass Vulnerability in upload_handle.php with POC and Mitigation

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