Binary Hacking

Intro:

I'm still learning new things every day, and this page is a reference for me. It will just be some commands of programs or small code snippits to help me understand this topic more. I recently started watching Liveoverflow. Most of the code snippits come from his video's. He also suggests to do lots of CTF's to learn and understand the topic more.

Assemble command codes:

Assembly code we read from the top to the bottom and follow the inscructions we encounter.

cmp	compair
jne	jump not equal
mov	move data to memory
call	call a function/ action
jmp	jumps to address
test	tests something
eip	Instruction Pointer
esp	Stack Pointer
ebp	Base Pointer
ret	return to ...

 

Register	Accumulator	Counter	Data	Base	Stack Pointer	Stack Base Pointer	Source	Destination
64 Bit	RAX	RCX	RDX	RBX	RSP	RBP	RSI	RDI
32 Bit	EAX	ECX	EDX	EBX	ESP	EBP	ESI	EDI
16 Bit	AX	CX	DX	BX	SP	BP	SI	DI

 

GDB commands:

gdb is a linux debugger, here some commands as a reference.

gdb "program"	start gdb to analize a program
set disassembly-flavor intel	Set the architectrure on intel
disasseble main	get debug code for main() function
break *main	set break point at main() break *0x00400607 to break at an address
run	runs programm again
si	To use with breakpoints: Step 1 instruction furter ( follows functions )
ni	To use with breakpoints: Next instruction ( don't follow functions )
continue	continue program to run to next breakpoint.
set $eax=0	change the register value of rax to 0
x/s "register address"	to print the value on this address.
define hook-stop	defines a series of commands on break to auto execute (hook-stop)
info registers	displays the register info
x/24wx $esp	get the stack ( $esp) 24 addresses
x/2i $eip	get the last 2 index pointer commands
end	ends the commands of a define hook.
r < caracters	read from file "caracters"
x 'function name'	Examines the function.

 

Special Codes:

\xCC	opcode CC is for setting breakpoints (int3)
\x90	NOP is no operations

 

Python snippits:

Some handy code snippits that makes life easy.

int('1111', 2)	15	Binair to Decimal
bin(15)	0b1111	Decimal to Binair
hex(15)	0xf	Decimal to Hex
hex(int(0b1111))	0xf	Binair to Hex
chr(0x41)	A	Hex to Char

import struct 
struct.unpack("I", "ABCD")[0]       # 1145258561 Integer of ABCD 
struct.pack("I", 1145258561)        # ABCD String of 1145258561

hex(struct.unpack("I", "ABCD")[0])  # 0x44434241 Hex value of ABCD 
hex(struct.unpack(">I", "ABCD")[0]) # 0x41424344 Revers Hex of ABCD 

struct.pack("I", 0x44434241)        # ABCD String of 0x44434241 
struct.pack("I", 0x41500000)        # \x00\x00PA String of 0x41500000