How to Minimize Buffer Overflow
1 Answer

1. Assessment of secure code manually: Buffer overflow occurs when a program or process tries to store more data in a buffer than it was intended to hold. Developers should be educated about minimizing the use of vulnerable functions available in C library, such as strcpy() , strcat() , sprintf() and vsprintf(), which operate on null-terminated strings and perform no bounds checking. The input validation after scanf() that reads user into a buffer is very essential.

2. Disable stack execution: Malicious Code causes input argument to the program, and it resides in the stack and not in the code segment. Any code that attempts to execute any other code residing in the stack will cause a segmentation violation. Therefore, the simplest solution is to invalidate the stack to execute any instructions. However, the solution is not easy to implement.

3. Compiler tools: Over the years, compilers have become more and more aggressive in optimizations and the checks they perform. Various compiler tools already offer warnings on the use of unsafe constructs such as gets(), strcpy(), etc. Developers should be educated to restructure the programming code if such warnings are displayed.

4. Dynamic run-time checks: In this scheme, an application has restricted access to prevent attacks. This method primarily relies on the safety code being preloaded before an application is executed. This preloaded component can either provide safer versions of the standard unsafe functions or it can ensure that return addresses are not overwritten. One example of such a tool is libsafe. The libsafe library provides a way to secure calls to these functions, even if the function is not available.

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