We are publishing this post in the hope that all Magento users can utilize this information to determine if their site has been compromised and take the steps required to correct the problem.
We were recently contacted by a client regarding a Common Point of Purchase Investigation that was initiated by a credit card issuer. These investigations are used to pinpoint the source of fraudulent activity reported by card holders. Our security team immediately began a comprehensive internal investigation to pinpoint the root cause of the fraudulent activity on the client’s account. Our security team found evidence of Magento core files having been modified to skim credit card data during the checkout process. The skimmed data would then be logged to a fake image file (actually a text file) located in the media folder, then the attacker would download these text files from a remote server.
Next, our security team began a scan of our entire infrastructure to determine if any other client sites were affected by the same exploit. We found a total of 39 sites (out of 15,000 Community and 1,500 Enterprise Magento stores) hosted with us, were affected by the same exploit. We immediately contacted all of the affected clients before their credit card processing companies had even detected a problem.
We have since cleaned all of the sites that were exploited and contacted all of the affected clients about the exploit.
PLEASE NOTE: If you are hosted with us and have not been contacted by our security team regarding this issue, then we believe your site has not been affected by this exploit. We are committed to the safety and security of your data and we take these issues very seriously. As a precaution, we are running hourly scans of our infrastructure to detect any further compromises.