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Understanding Buffer Overflow Attacks and Frame Pointer Manipulation Techniques

This document delves into the mechanics of buffer overflow attacks, with an emphasis on frame pointer manipulation and its implications for system security. It explores how attackers can exploit vulnerabilities to overwrite return addresses and gain unauthorized shell access through carefully crafted input. The study includes practical examples detailing the memory addresses used, various assembly instructions involved, and the role of stack frames in the exploitation process. It serves as a comprehensive guide for cybersecurity professionals seeking to enhance their understanding of attack vectors and defenses.

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Understanding Buffer Overflow Attacks and Frame Pointer Manipulation Techniques

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  1. CS419/579Cyber Attacks & Defense Frame Pointer (i.e., Base Pointer, ebp) Attack 10/10/19

  2. Points to somewhere up… Buffer Overflow NO ARG… get_a_shell() 0x64646464 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • 4 byte buffer… • What if you type “1111aaaabbbbccccddddeeee”? • Overwrites the return address! • Can you set that as the address of • get_a_shell()?

  3. Points to somewhere up… Buffer Overflow NO ARG… get_a_shell() 0x64646464 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  4. Points to somewhere up… Buffer Overflow NO ARG… get_a_shell() 0x64646464 %ebp 0x63636363 %esp 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  5. Points to somewhere up… Buffer Overflow NO ARG… get_a_shell() 0x64646464 %esp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  6. Points to somewhere up… Buffer Overflow NO ARG… %ebp: 0x64646464, INVALID get_a_shell() %esp 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  7. Points to somewhere up… Buffer Overflow NO ARG… %ebp: 0x64646464, INVALID %esp get_a_shell() 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 Run get_a_shell()! ARG1: 41414141 Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  8. Points to somewhere up… Function Epilogue NO ARG… RET_ADDR Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  9. Points to somewhere up… Function Epilogue NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 %esp 0x62626262 Move %esp back to the previous point… 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input add $0x54,%esp pop %esi pop %ebp ret

  10. Points to somewhere up… Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp Function return of receive_input leave ret The leave instruction mov %ebp, %esp pop %ebp

  11. Points to somewhere up… Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  12. Points to somewhere up… Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  13. Points to somewhere up… Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %esp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  14. Points to somewhere up… Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %esp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  15. Points to somewhere up… %ebp Function Epilogue - leave NO ARG… get_a_shell() RET_ADDR %esp 0x64646464 Saved %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  16. Points to somewhere up… %ebp Function Epilogue - leave NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 Saved %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 Function return of receive_input leave ret Function return of receive_input leave mov %ebp, %esp pop %ebp ret

  17. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • The %ebpregister • %esppoints to one end of a function’s stack • %ebppoints to the other end of a function’s stack • A function’s Stack Frame • Starts with %ebp • Ends with %esp

  18. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 Saved %ebp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address?

  19. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address?

  20. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  21. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 %esp • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  22. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 %esp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  23. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 %esp %ebp 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • What if an attacker … • Can overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  24. %ebp 0x64646464 Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR %esp 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • What if an attacker can… • Overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  25. %ebp 0x64646464 Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR %esp 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • What if an attacker can… • Overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret

  26. %ebp 0x64646464 Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • What if an attacker can… • Overwrite saved %ebp • But cannot overwrite return address? • Function epilogue • leave • mov %ebp, %esp • pop %ebp • ret • Return to the correct RET_ADDR • Is it problematic????

  27. %ebp 0x64646464 Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • Call chain (in bof-level5) • main() -> run() -> receive_input() • We just ran leave-ret in receive_input() • There will be another leave-ret in run() • What will happen if that runs???

  28. %ebp 0x64646464 Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • Call chain (in bof-level5) • main() -> run() -> receive_input() • leave-ret in run() • leave • mov %ebp, %esp • pop %ebp • ret

  29. %ebp 0x64646464 Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • Call chain (in bof-level5) • main() -> run() -> receive_input() • leave-ret in run() • leave • mov %ebp, %esp • pop %ebp • ret

  30. %esp %ebp 0x64646464 Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 ARG1: 41414141 • Call chain (in bof-level5) • main() -> run() -> receive_input() • leave-ret in run() • leave • mov %ebp, %esp • pop %ebp • ret

  31. %esp %ebp 0x64646464 Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0x63636363 0x62626262 0x61616161 0x31313131 Buffer at ebp-0x10 Invalid Address 0x64646464!! ARG1: 41414141 %esp = 0x64646464 pop %ebp -> mov(%esp), %ebp add $4, %esp • Call chain (in bof-level5) • main() -> run() -> receive_input() • leave-ret in run() • leave • mov %ebp, %esp • pop %ebp • ret

  32. GDB, break at receive_input’s leave dddd = 0x64646464 Leave mov %ebp, %esp pop %ebp %esp = 0xffffd3e0 %ebp = 0xffffd468

  33. GDB, break at receive_input’s leave dddd = 0x64646464 Leave mov %ebp, %esp pop %ebp %esp = 0xffffd46c %ebp = 0x64646464

  34. GDB, break at run’s leave dddd = 0x64646464 Leave mov %ebp, %esp pop %ebp %esp = 0xffffd470 %ebp = 0x64646464

  35. GDB, break at run’s leave dddd = 0x64646464 Leave mov %ebp, %esp pop %ebp<- fault! %esp = 0x64646464 %ebp = 0x64646464

  36. Exploiting Frame Pointer • We can change the saved %ebp • The %ebpof a function in the upper level • main() -> run() -> receive_input() • (%ebp + 4) stores ‘return address!’ • If that is invalid address such as 0x64646464 • Will generate SIGSEGV, a segmentation fault • What if we put a valid address on it???? • The address that we can control…

  37. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 %esp Let’s put a stack address at saved %ebp… Suppose our original %ebp = 0xffffd540 ebp-0x10 = 0xffffd530

  38. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 %esp • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  39. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 %ebp 0x63636363 0x62626262 0x61616161 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 %esp • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  40. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 %ebp %esp 0x63636363 0x62626262 0x61616161 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  41. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 %ebp %esp 0x63636363 0x62626262 0x61616161 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  42. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR %esp 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  43. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR %esp 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  44. Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – receive_input • leave • mov %ebp, %esp • pop %ebp • ret

  45. Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

  46. Frame Pointer Attack NO ARG… %esp get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

  47. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %esp %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

  48. Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 0x31313131 %esp %ebp 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

  49. 0x31313131 %ebp Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 %esp 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

  50. 0x31313131 %ebp Frame Pointer Attack NO ARG… get_a_shell() RET_ADDR 0x64646464 0xffffd530 0x63636363 0x62626262 0x61616161 %esp 0x31313131 0xffffd530 Buffer at ebp-0x10 ARG1: 41414141 • Function epilogue – run() • leave • mov %ebp, %esp • pop %ebp • ret

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