Skip to content

Commit

Permalink
MIT license.
Browse files Browse the repository at this point in the history
  • Loading branch information
yallie committed Apr 26, 2018
1 parent 243fad1 commit baec5a4
Show file tree
Hide file tree
Showing 2 changed files with 59 additions and 4 deletions.
21 changes: 21 additions & 0 deletions LICENSE
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
MIT License

Copyright (c) 2018 Alexey Yakovlev

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
42 changes: 38 additions & 4 deletions README.md
Original file line number Diff line number Diff line change
@@ -1,23 +1,57 @@
# Deserializing the untrusted data is dangerous

This tiny library tries to fix several known BinaryFormatter vulnerabilities.
It's proven that deserialing arbitrary payloads under certain conditions can
trigger code execution. BinaryFormatter, DataContractSerializer, XmlSerializer,
as well as several widely used JSON serializers are known to be vulnerable.

See [ysoserial.net](https://github.com/pwntester/ysoserial.net) project for details.

This tiny library tries to fix several known BinaryFormatter vulnerabilities.
When a malicious payload is detected, the library throws an exception instead of
deserializing the data.

[![appveyor](https://ci.appveyor.com/api/projects/status/github/zyanfx/safedeserializationhelpers?svg=true)](https://ci.appveyor.com/project/yallie/safedeserializationhelpers)
[![tests](https://img.shields.io/appveyor/tests/yallie/safedeserializationhelpers.svg)](https://ci.appveyor.com/project/yallie/safedeserializationhelpers/build/tests)

# Code sample

```csharp
// bad: deserialization can trigger arbitrary code execution
// unsafe: deserialization can trigger arbitrary code execution
var fmt = new BinaryFormatter();
var object = fmt.Deserialize(stream);

// better: deserialization is checked against known vulnerabilities
// safe: deserialization is guarded against known vulnerabilities
var fmt = new BinaryFormatter().Safe();
var object = fmt.Deserialize(stream);
```

# Usage

TODO: publish a Nuget package
TODO: publish a Nuget package

# Known vulnerabilities supported by the library

* **ActivitySurrogateSelector** gadget by James Forshaw (loads an assembly and executes arbitrary code).
* **PSObject** gadget by Oleksandr Mirosh and Alvaro Munoz. Target must run a system not patched for CVE-2017-8565.
* **TypeConfuseDelegate** gadget by James Forshaw (runs any process using Process.Start delegate).
* **DataSet** gadget by James Forshaw (unsafe BinaryFormatter deserialization).
* **WindowsIdentity** gadget by Levi Broderick (unsafe BinaryFormatter deserialization).

# References

* [Exploiting .NET Managed DCOM](https://googleprojectzero.blogspot.com/2017/04/exploiting-net-managed-dcom.html) by James Forshaw
* [Are you my Type?](https://media.blackhat.com/bh-us-12/Briefings/Forshaw/BH_US_12_Forshaw_Are_You_My_Type_WP.pdf) by James Forshaw
* [Attacking .NET serialization](https://speakerdeck.com/pwntester/attacking-net-serialization) by Alvaro Munoz
* [ysoserial.net](https://github.com/pwntester/ysoserial.net) exploit collection by Alvaro Munoz

# Thanks

* [Markus Wulftange](https://github.com/mwulftange) — for bringing up the problem to my attention
* [James Forshaw](https://github.com/tyranid) — for the great blog posts, papers and talks on the subject
* [Alvaro Munoz](https://github.com/pwntester) — for the awesome educational ysoserial.net project
* [Chris Frohoff](https://github.com/frohoff) — for the original ysoserial Java project
* [Levi Broderick](https://github.com/GrabYourPitchforks), Oleksandr Mirosh — for more malicious gadgets

# License

MIT License.

0 comments on commit baec5a4

Please sign in to comment.