A method makes use of positional relationships in a memory stack between the frame pointer, such as the Extended Base Pointer (EBP) in Windows®-based systems, of a critical call initiating function making a call to a critical operating system (OS) function, the top of stack position, such as the Process Environment Block (PEB) in Windows® based systems, and the bottom of stack position, such as the Extended Stack pointer (ESP) in a Windows® based system, to detect and block buffer overflows.