Security – Why Magento POSTs to /app/etc/local.xml

According to Magento:

Strong Data Encryption, Hashing and Key Management Strong data encryption based on AES-256 and strong hashing based on SHA-256. Database keys are easily managed and updated.

From my understanding and some quick glances at code:

Community is mainly Mcrypt and Blowfish (ECB Mode) based, as Don pointed out in the comments.

• https://github.com/OpenMage/magento-mirror/blob/magento-1.9/lib/Varien/Crypt/Mcrypt.php#L102
• http://php.net/manual/en/function.mcrypt-generic.php
• https://en.wikipedia.org/wiki/Mcrypt

Enterprise uses a custom class for PCI compliance which uses both Mcrypt and Blowfish as with different cyphers and stronger encryption.

MCRYPT_RIJNDAEL_128,MCRYPT_RIJNDAEL_256,HASH_VERSION_SHA256,etc.

• https://en.wikipedia.org/wiki/Blowfish_(cipher)

Both using a combination of MD5, salting and hashes.

You can override the encryption models if you wished to use your own:

 /**
 * @return Mage_Core_Model_Encryption
 */
public function getEncryptor()
{
    if ($this->_encryptor === null) {
        $encryptionModel = (string)Mage::getConfig()->getNode(self::XML_PATH_ENCRYPTION_MODEL);
        if ($encryptionModel) {
            $this->_encryptor = new $encryptionModel;
        } else {
            $this->_encryptor = Mage::getModel('core/encryption');
        }

        $this->_encryptor->setHelper($this);
    }
    return $this->_encryptor;
}

• https://github.com/OpenMage/magento-mirror/blob/magento-1.9/app/code/core/Mage/Core/Helper/Data.php#L79

With that said, storing Credit Card data makes you a target and future legal issues possibly.

However I have seen scrapping hacks that are capturing data input before it is encrypted and logging it. So simply not storing them makes you immune either. This is proof that other exploits outside of Magento in its stack should always be considered.

As far as encryption strength, that would be a better question for:

• https://crypto.stackexchange.com/

Other related documents to read:

• https://en.wikipedia.org/wiki/Secure_Hash_Algorithm
• http://docs.php.net/mcrypt_create_iv
• https://stackoverflow.com/q/401656/158325

Unless the script contains means by which to alter content in the Magento install via something like arguments sent to the script then no I don't see that it's a security risk - including Mage.php is only exactly what index.php (also at web root) does too.