Under very specific circumstances (see Required configuration section below), a privileged user is able to cause arbitrary code to be executed which may cause further disruption to services. This is specific to applications written in C#. This affects all MongoDB .NET/C# Driver versions prior to and including v2.18.0
Following configuration must be true for the vulnerability to be applicable: * Application must written in C# taking arbitrary data from users and serializing data using _t without any validation AND
- Application must be running on a Windows host using the full .NET Framework, not .NET Core AND
- Application must have domain model class with a property/field explicitly of type System.Object or a collection of type System.Object (against MongoDB best practice) AND
- Malicious attacker must have unrestricted insert access to target database to add a _t discriminator.Following configuration must be true for the vulnerability to be applicable
Weakness
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| C#_driver |
Mongodb |
* |
2.19.0 (excluding) |
Potential Mitigations
- Make fields transient to protect them from deserialization.
- An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.
References