Modern Binary
Exploitation Writeups-0x02
This is the 2nd writeup of Tools and Basic Reverse Engineering by RPISEC, a subpart of Modern Binary Exploitation Course.
Link of lectures:- http://security.cs.rpi.edu/courses/binexp-spring2015/
All the lecture materials and other necessary files are available on the above link to check it out.
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crackme0x00b
Information gathering using the file command
$file crackme0x00b
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Information gathering using the rabin2 tool.
$rabin2 -I crackme0x00b
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The given crack me is 32 bits and little endian, make a note of this it will help to find out the way to crack.
Cracking the file using strings
$strings -e L crackme0x00b
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Cracking the file using xxd
$xxd crackme0x0b
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Cracking the file using rabin2
$rabin2 -z crackme0x00b
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Cracking the file using radare2
$radare2 crackme0x00a
[0x080483e0]> aaa
[0x080483e0]> pdf @ main
- aa:-analyze all.
- aaa:- analyze all with more info.
- pdf:- print disassemble function.
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wcscmp() use *s1 and *s2 variable s1 is pointing to w0wgreat and s2 is the input strings.
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Cracking the file using gdb-peda
gdb-peda is like an addon for gdb, you can install it from GitHub.
$gdb crackme0x00a
>gdb-peda$ disassemble main
disassemble main will show the main function of the binary.
gdb-peda$ break *0x080484ce
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gdb-peda$ run
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gdb-peda$ ni
ni or nexti — execute calls as one instruction.
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gdb-peda$ telescope $edx
The telescope view shows stack values, and also attempts to dereference pointers which may be pointed to by the stack.
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There is one more way to do that above thing
gdb-peda$ x/25s $edx
x/ :- show bytes
25:- how many we want to show
s:- as a strings
$edx:- this refers to the register
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