There have been a few high profile incidents of online retailers seeing their customer’s credit card data being siphoned off to places like Lithuania due to a bit of malicious code being stuck onto their website pages, usually under the term “Magecart”.
One effect of this is that the padlock, used as an indication that the site your are visiting is reputable, is still visible when in fact your data is being shipped off to the Dark Web.
The simple fix for all you webmasters out there is to keep a golden offline copy of your website before you release it and then to script a compare between what you have out on your public server and this protected, secure copy.
For those a bit unsure of their options on zero budget, I recommend a trip to the following site:
https://www.softwaretestinghelp.com/compare-two-files-unix/
