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Downloads. rpisec.org/2013/09-13-2013/exploitation.zip For the lazy – rpisec.org/2013/ Windows & Linux Binaries! … macs?. RPISEC. Intro to Memory Corruption Fall 2013. Memory Corruption .

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  1. Downloads • rpisec.org/2013/09-13-2013/exploitation.zip • For the lazy – rpisec.org/2013/ • Windows & Linux Binaries! • … macs? Intro to Memory Corruption

  2. RPISEC Intro to Memory Corruption Fall 2013 Intro to Memory Corruption

  3. Memory Corruption • The simplest definition – To change data the program uses in ways that were not intended by the programmer • So what does this actually mean? And what can we do with it? • Let’s take a look at exercise one Intro to Memory Corruption

  4. /exploitation/one/ hands on activity time! Intro to Memory Corruption

  5. Uhm… what even just happened? • You just overflowed your first buffer! But in a controlled manner • A more reckless overflow would probably result in the program segfaulting • segfault: An error reading/writing to memory Intro to Memory Corruption

  6. The technical explanation • The stack is how a program maintains variables and their data during execution • This is main()’s stack --------> • Omgwut have we done • Is_zero == ‘U’ == 85 Intro to Memory Corruption

  7. /exploitation/two/ pretty similar to /one/ Intro to Memory Corruption

  8. Now let’s take it a bit further… • What if we overwrote the return address that’s stored further down the stack? • The return address tells the program where to go after a completing a function call • In this case, we’d segfault… but what if we set it to something more meaningful than AAAA? Intro to Memory Corruption

  9. /exploitation/easy/ let’s try something crazier Intro to Memory Corruption

  10. “If your program simply segfaulted, consider yourself lucky.” -Chuck Stewart Intro to Memory Corruption

  11. Security • What we just did was take control of the program’s execution flow, and bend it the way of our will • What if this program was running on a server? Or perhaps running under an admin user? • Security – To ensure and maintain complete control of the execution flow of your program Intro to Memory Corruption

  12. Recap of ‘easy’ • This time, we overwrote the return address, effectively telling the program where it should go next • What if we could insert our OWN code into the program, and point the return address towards that? - ‘shellcode’ • … Next time ;) Intro to Memory Corruption

  13. Some final words • To really become good at exploitation, you need to have a solid grasp on the low level stuff • This means knowing x86 assembly, how the stack works, and how data is typically laid out in memory Intro to Memory Corruption

  14. If you like what we did here… • Welcome to real Hacking! • Related wargames: • io.smashthestack.org • exploit-exercises.com/protostar • Come to our ‘advanced’ meeting, Wednesday! • We’ll be rolling our own shellcode :> Intro to Memory Corruption

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