Card skimming and card details theft is one such sophisticated technique attack that seldom fails.
Earlier this week, cybersecurity researchers at Sucuri blog unmasked a malicious campaign where a credit card swiper was injected into WordPress’ wp-settings.php file. The WooCommerce customers reported that images were disappearing from the cart almost as soon as they were uploaded.
According to researchers, the credit card skimmer was buried deep down into the file titled '../../Maildir/sub.main', and it was easy to miss on a casual review. Scammers usually prefer to deploy malicious content out of the way so it is more difficult to detect. The common tactic employed is to create directories that look like system directories, or to place malware in existing core CPanel or other server directories.
Upon analyzing the malicious file, researchers uncovered over 150 lines of code that had been obfuscated with str_rot13 and base64. Attackers also used multiple functions to store credit card data concealed in the wp-content/uploads/highend/dyncamic.jpg image file. When decoded, that data revealed not only credit card details submitted to the site, but also admin credentials to the site’s backend.
Injecting card skimmers into WordPress plugin files is the newest trend, avoiding the heavily watched ‘wp-admin’ and ‘wp-includes’ core folders, where most injections are short-lived. It is one of the most lucrative and stealth attack tactics employed by scammers to make money.
There are a couple reasons why this is a useful tactic. The primary reason is that it makes it very easy for scammers to download the stolen details in their browser or a console. Secondly, most website/server malware detection scans focus on website file extensions such as PHP, JS, and HTML. Image files, particularly those in a wp-content/uploads sub-directories, can sometimes be overlooked.
“Scammers are aware that most security plugins for WordPress contain some way to monitor the file integrity of core files (that is, the files in wp-admin and wp-includes directories). This makes any malware injected into these files very easy to spot even by less experienced website administrators. The next logical step for them would be to target plugin and theme files,” researchers explained.
