SUPEE-5344 is an official security patch to the infamous Magento shoplift bug. This bug allows bad actors to obtain admin access to vulnerable Magento sites. The patch was released February 2015 but many sites unfortunately did not update. This gave hackers an opportunity to compromise thousands of Magento powered online stores. The most important patch that should be applied to all Magento versions released prior to February 2015. The code actually belonged to a Magento credit card stealing malware which exploited the very bug that SUPEE is supposed to be fixing.”]
Source: https://blog.sucuri.net/2016/02/fake-supee-5344-patch-steals-payment-details.html