Question

1. Stack buffer overflow
   1. Memory Architecture. Describe the stack in the address space of the VM, in generalities. Specifically, address where in memory the stack would be located, what the stack structure looks like when data is pushed onto the stack and popped off the stack. Discuss what register values are placed onto the stack, where user variables are placed within the stack, where arguments would be placed in the stack relative to pertinent register storage within the stack, and finally how program control flow is implemented using the stack. How does the stack structure get affected when a buffer of size ‘non-binary’ is allocated by a function (ie – buffer size which causes misalignment within the stack)? When a stack grows, in which direction, relative to overall memory, does a stack consume memory?
   2. Write a testing program (not sort.c from task 2) that contains a stack buffer overflow vulnerability. Show what the stack layout looks like and explain how to exploit it. In particular, please include in your diagram: (1) The order of parameters (if applicable), return address, saved registers (if applicable), and local variable(s), (2) their sizes in bytes, (3) size of the overflowing buffer to reach return address, and (4) the overflow direction in the stack (5) What locations within the stack are actually overwritten with your target data to exploit a stack to cause the routine you want to execute to be invoked? You are not required to write the real exploit code, but you may want to use some figures to make your description clear and concise.

Answer 1