-
Cheatsheet utility for assembling, disassembling and debugging files from terminal.
-
Assembler.sh Bash script to automate process of assembling and debugging a file.
Instructions to assemble code and generate an executable file (Linux enviroment) :
An assembly script usually has the (.s extension)
use nasm to convert it to machine code (.o extension): nasm -f elf64 fibonacci.s
then link it using ld, it will generate the actual executable: ld -o fibonacci ficonacci.o
Bash script that automate the process of compiling, linking and running assembly script
usage:
./assembler.sh filename.s
It will disassemble an executable into assembly instructions. It will allow you to study the corresponding assembly instructions of an executable file.
objdump -M intel -d filename
Show cleaner output (no hex values):
objdump -M intel --no-show-raw-insn --no-addresses -d helloWorld
Show data section values of the executable :
objdump -sj .data helloWorld
Gnu debugger is an utility integrated in linux, used with gef extensions it allows you to debug executable applications in terminal.
INSTALL GEF (LINUX GNU HACKER PLUGIN)
wget -O ~/.gdbinit-gef.py -q https://gef.blah.cat/py echo source ~/.gdbinit-gef.py >> ~/.gdbinit
USAGE: IT WILL DISASSEMBLE AND DEBUG AN EXECUTABLE
gdb -q ./helloWorld
NOW YOU CAN USE BASH SCRIPT TO ASSEMBLE AND DEBUG AN EXECUTABLE:
./assembler.sh helloWorld.s -g
OUTPUT, you entered in gdb menu:
DISPLAY INFO LIST USING:
gef➤ info
PUT BREAKPOINT AT A FUNCTION:
gef➤ b _start
gef➤ r
IT WILL DISPLAY ACTUAL STATUS OF REGISTERS AND APPLICATION EXECUTION AT BRAKEPOINT. Note: the instruction shown with the -> symbol is where we are at, and it has not yet been processed.
