These operators are designed to read data into a buffer until they reach a null terminator. Most buffer overflow vulnerabilities boil down to the use of unbounded read or copy operators like strcpy and strcat in C++. This typically is only an issue when dealing with user-controlled data. As long as the data fits in the allocated variable buffer, then everything works out.īuffer overflow vulnerabilities are created when the developer does not account for and control the potential case where the allocated buffer is not large enough to hold the data that is to be placed in it. When placing data on the stack, a developer can allocate a variable with a set size to hold that data and then fill it with data. If an attacker can rewrite the function return address, they can control the execution flow of the program and potentially convince it to run attacker-controlled malicious code. As shown, a function’s stack includes function arguments/parameters, local variables and the function’s return address. The image above shows a sample program stack. It grows when new values are added to the top of it, like a stack of papers (hence the name). The stack is a region of memory where a program can store values for later use. While both of these can be the victim of buffer overflow attacks, stack-based ones are the best place to begin. When a program is running, this “somewhere” is either the stack or the heap. This reduces the risk that buffer overflow attacks pose to corporate application security (AppSec).Every piece of data on a computer that is used by a program has to be stored somewhere. Preventing Vulnerability Exploitation: Web application firewalls (WAFs) and Web Application and API Protection (WAAP) solutions can identify and block attempted exploitation of buffer overflow vulnerabilities.The use of other programming languages such as Python, Java, or C# makes buffer overflows difficult or impossible. Using Memory-Safe Languages: Buffer overflows occur in programming languages with fixed-size variables and no memory protections. Buffer overflow vulnerabilities can be avoided by properly using the safe versions of these functions. Avoiding Vulnerable Functions: Buffer overflows are made possible by vulnerable functions such as gets, scanf, and strcpy in C/C++.Enabling these protections makes buffer overflow attacks much more difficult to perform. Enabling Runtime Memory Protection: Most computers have built-in protections against buffer overflows such as Address Space Layout Randomization (ASLR), Data Execution Prevention (DEP), and Structured Exception Handling Overwrite Protection.Checking the length of data or only copying a certain number of bytes to a memory location can help avoid buffer overflows. Performing Input Validation: Buffer overflow vulnerabilities occur when a program makes assumptions about user-provided input without validating these assumptions.If user-provided data is interpreted as a format string, it can be used to leak or modify sensitive values.īuffer overflow vulnerabilities can be prevented by:
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