ASLR: Address Space Layout Randomization

• Problem it kills: exploits with hardcoded addresses (buffer address, libc system, gadget offsets).
• Idea: randomize base addresses each run, so the attacker cannot know where anything is.
• Randomized regions: stack, heap, mmap (shared libraries), and — if the binary is PIE — the executable image itself.
• Entropy = bits of randomness. More bits = harder to guess. 64-bit gives far more entropy than 32-bit (where brute force was often feasible).