EC521 Memory Corruption Visualizations

Interactive x86-32 visualizations for understanding stack memory layout and buffer overflow attacks. Built for Boston University's EC521 course.

Visualizations

function-call.html

Step-by-step walkthrough of how the stack frame is set up and torn down during a function call. Based on a simple C program where main() calls inc(num).

Covers:

• Function prologue (push ebp / mov ebp, esp / sub esp)
• Local variable allocation and access via [ebp - offset]
• Argument passing via the stack (cdecl calling convention)
• The call instruction pushing the return address
• Function epilogue (leave / ret) restoring ESP, EBP, and EIP

buffer-overflow.html

Interactive demonstration of a stack-based buffer overflow using strcpy. Type input in real-time and watch it overflow from buffer[12] into adjacent stack memory.

Covers:

• Why strcpy is dangerous (no bounds checking)
• Overwriting adjacent local variables (username)
• Corrupting the saved frame pointer (EBP)
• Overwriting the return address for arbitrary code execution
• Supports \xNN hex escape sequences in input (e.g., \xef\xbe\xad\xde)

Usage

Open either HTML file directly in a browser. No build step, server, or dependencies required.

• Arrow keys or buttons to step through instructions
• Preset buttons to load example inputs
• Live mode (buffer overflow) updates the stack as you type