问题描述
在这个链接上，在备注部分提到:
On this link, in remarks section it's mentioned that:
TypeNameHandling.使用 TypeNameHandling.None 以外的值反序列化时，应使用自定义 SerializationBinder 验证传入类型.
在什么情况下，使用 TypeNameHandling.All 序列化/反序列化来自外部源的 JSON 会有害?一个工作示例将不胜感激.
In what cases JSON from external source would be harmful if serialized/deserialized with TypeNameHandling.All? A working example would be appreciated.
推荐答案
当使用 TypeNameHandling.All 反序列化并且没有 SerializationBinder 检查时，json.net 将尝试创建一个类型为JSON 中的元数据.
When deserialize with TypeNameHandling.All and without a SerializationBinder checks json.net will try to create a instace of the type that comes as metadata in the JSON.
public class Car
{
public string Maker { get; set; }
public string Model { get; set; }
}
{
"$type": "Car",
"Maker": "Ford",
"Model": "Explorer"
} //create a Car and set property values
但是攻击者可能会向您发送存在于您的代码或框架中的危险类型.
But an attacker could send you dangerous types that exist in your code or in the framework.
即来自这里 System.CodeDom.Compiler.TempFileCollection 是一个可序列化的类，其目的是维护编译过程中产生的临时文件列表，并在不再需要时将其删除.为了确保文件被删除，该类实现了一个终结器，当垃圾收集器清理对象时将调用该终结器.攻击者将能够构建此类的序列化版本，将其内部文件集合指向受害者系统上的任何文件.这将在反序列化后的某个时刻被删除，而无需与反序列化应用程序进行任何交互.
i.e. from here System.CodeDom.Compiler.TempFileCollection is a serializable class whose purpose is to maintain a list of temporary files which resulted from a compilation process and delete them when they are no longer needed. To ensure that the files are deleted the class implements a finalizer that will be called when the object is being cleaned up by the Garbage Collector. An attacker would be able to construct a serialized version of this class which pointed its internal file collection to any file on a victims system. This will be deleted at some point after deserialization without any interaction from the deserializing application.
[Serializable]
public class TempFileCollection
{
private Hashtable files;
// Other stuff...
~TempFileCollection()
{
if (KeepFiles) {return}
foreach (string file in files.Keys)
{
File.Delete(file);
}
}
}
{
"$type": "System.CodeDom.Compiler.TempFileCollection",
"BasePath": "%SYSTEMDRIVE",
"KeepFiles": "False",
"TempDir": "%SYSTEMROOT%"
} // or something like this, I just guessing but you got the idea
这篇关于Newtonsoft Json 中的类型名称处理注意事项的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！