The one problem that a lot of people have when it comes to the security of their web site is that they complain about not being able to see when an attack has been done to the site. They want to know that their customers are in danger before they are attacked and not afterwards. That is not always possible and sometimes you have to realize that most of computer security happens on a defensive measure and not an offensive one. But luckily there are some signs that you can look for when it comes to some attacks. Not all attacks will follow this measure but some will.
A lot of the time when an exploit has been placed on your web site, it has been done through the injection of code on the site. While the code is place there, your visitors and you are going to the site not noticing that anything is wrong. But the code that is there is very slick. It has a function that allows it to access a certain part of memory through an exploit. And how do we know that it is trying to access a certain part of the memory on the computer? Because we can see the hexadecimal code that is inside of the code. The computer uses hexadecimal numbers to represent different parts of data. The hexadecimal numbers that is in that code is giving instructions to the computer to follow.
If you were able to translate Hexadecimal into base 10 numbers then you would be able to figure out what the instructions are telling the computer. But just being able to recognize the numbers are enough for you to erase them out of the code. There are some but very few legitimate programs that are going to place Hexadecimals in your source code in that manner so it usually a sure sign of an attack.