![]() ![]() While some pieces of modern operating systems still have to use these physical memory addresses, all of today's operating systems use a scheme called virtual memory. In the early days of computing, processors and operating systems used physical memory addresses: each memory address corresponded directly to a particular piece of RAM. This means that every function of a running program also has an address. System memory isn't just used for data it's also used for the executable code that makes up our software. When the processor loads and stores data from main memory (RAM), it uses the memory address of the location it wants to read and write from. Every individual byte of memory has a corresponding numeric address. The most important central concept is the memory address. To understand how these attacks work and some of the things people do to try to stop them, we first have to understand a little about how that memory is used. Different operating systems have their own quirks, but every platform in common use today follows essentially the same pattern. The overflows are tied to the way the processor and native code programs manipulate memory. It's not the only kind of overflow issue, but it's the classic, best-known kind.) Stack it upīuffer overflows create problems only for native code-that is, programs which use the processor's instruction set directly rather than through some intermediate form such as in Java or Python. To understand why buffer overflows happen-and why their impact is so grave-we need to understand a little about how programs use memory and a little more about how programmers write their code. (Note that we'll look primarily at the stack buffer overflow. You'd be right to think that. Yet buffer overflows continue to happen, and the results are frequently a security catastrophe. After all, the program knows how big the buffer is, so it should be simple to make sure that the program never tries to cram more into the buffer than it knows will fit. On the face of it, this sounds like a pretty foolish error. A buffer overflow happens when more data is written to or read from a buffer than the buffer can hold. Programs allocate finite-sized blocks of memory-buffers-to store this data as they work on it. Computer programs frequently operate on chunks of data that are read from a file, from the network, or even from the keyboard. And just this May, a buffer overflow found in a Linux driver left (potentially) millions of home and small office routers vulnerable to attack.Īt its core, the buffer overflow is an astonishingly simple bug that results from a common practice. ![]() Windows infamously revamped its security focus after two buffer overflow-driven exploits in the early 2000s. Twenty-seven years later, buffer overflows remain a source of problems. In fact the first self-propagating Internet worm-1988's Morris Worm-used a buffer overflow in the Unix finger daemon to spread from machine to machine. The buffer overflow has long been a feature of the computer security landscape. ![]() Aurich Lawson / Thinkstock reader comments 223 with ![]()
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