What Is Data Execution Prevention (DEP)?

In the great early 2000s, computer users were concerned about viruses. They'd heard stories of people getting their computers stolen and data being stolen when they used public computers. So they started installing anti-virus software. That wasn't enough to protect them from all of their threats. They also needed a way to protect themselves from memory-based exploits, which were the most significant threat. So Microsoft introduced DEP (data execution prevention), a security feature within operating systems, hardware- and software-enforced technology that prevents applications from executing code from non-executable memory locations. It was first included in Windows XP Service Pack 2 and has been on Linux and Mac OS since around 2004. Many people think that DEP is a dull, technical thing. It's fantastic! DEP stands for Data Execution Prevention, a security mechanism built into your computer to protect you from viruses and other threats. It works by scanning the memory heaps and stacks for loading data into the memory. So if you're running an application with DEP enabled, and someone tries to run code stored in memory, the CPU will mark all memory locations flagged with an attribute value for non-execution. That way, there's no way for the code to execute—it can't get past this roadblock! An exception is sent to the primary OS security mechanism when an abnormality is detected in these locations regarding code execution. So now we know something's going wrong, but we don't know what yet! That's where software-enforced DEP comes in. It only checks for an exception within the functions table of the primary application—this protects against buffer overflow attacks where hackers try to exploit vulnerabilities by overflowing buffers or overwriting executable code sections with their malicious code (which would usually be stored somewhere else).