One Article Review
| Source |  Code White |
|---|---|
| Identifiant | 5431240 |
| Date de publication | 2022-06-28 16:00:56 (vue: 2022-06-28 14:05:35) |
| Titre | Bypassing .NET Serialization Binders |
| Texte | Serialization binders are often used to validate types specified in the serialized data to prevent the deserialization of dangerous types that can have malicious side effects with the runtime serializers such as the BinaryFormatter. In this blog post we'll have a look into cases where this can fail and consequently may allow to bypass validation. We'll also walk though two real-world examples of insecure serialization binders in the DevExpress framework (CVE-2022-28684) and Microsoft Exchange (CVE-2022-23277), that both allow remote code execution. Introduction Type Names Type names are used to identify .NET types. In the fully qualified form (also known as assembly qualified name, AQN), it also contains the information on the assembly the type should be loaded from. This information comprises of the assembly's name as well as attributes specifying its version, culture, and a token of the public key it was signed with. Here is an (extensive) example of such an assembly qualified name:  System.Collections.Concurrent.ConcurrentBag`1+ListOperation[ [System.Object, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]],System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 This assembly qualified name comprises of two parts with several components: Assembly Qualified Name (AQN) Type Full Name Namespace Type Name Generic Type Parameters Indicator Nested Type Name Generic Type Parameters Embedded Type AQN (EAQN) Assembly Full Name Assembly Name Assembly Attributes You can see that the same breakdown can also be applied to the embedded type's AQN. For simplicity, the type info will be referred to as type name and the assembly info will be referred to as assembly name as these are the general terms used by .NET and thus also within this post. Th |
| Envoyé | Oui |
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