GDB Cheat Sheet

This are just important stuff that I have used.

• Managing inputs for payload injection

  • Getting inputs from char *argv[] $> ./program $(echo -ne "\xef\xbe\xad\xde")

  (gdb) run $(echo -ne "\xef\xbe\xad\xde")
  

  • Getting inputs from a file $> ./program ./myfile.txt

  (gdb) run myfile.txt
  

  • Getting inputs from stdin $> cat ./mycommands.txt | ./program || echo -ne "\xef\xbe\xad\xde" | ./program

  (gdb) run < ./mycommands.txt
    
  # or
    
  run < <(echo -ne "\xef\xbe\xad\xde")
  

  • Getting inputs from network $> echo -ne "\xef\xbe\xad\xde" | nc -vv localhost 666

  # keep stdin open after injection
  (cat ./mycommands.txt; cat) | ./program
    
  # or
  $> (echo -ne "\xef\xbe\xad\xde"; cat) | ./program
    
  # or
  $> (echo -ne "\xef\xbe\xad\xde"; cat) | nc -vv localhost 666
  

• Breaking at main in stripped binaries

  # option 1
  set breakpoint pending on
  starti
  break __libc_start_main
  continue
  b *$rdi
  continue
    
  # option 2
  set breakpoint pending on
  set $base = 0x555555554000
  b *($base+offset)