66 lines
1.6 KiB
Plaintext
66 lines
1.6 KiB
Plaintext
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=== How to fix it in .NET
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The following code is vulnerable to deserialization attacks because it
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deserializes HTTP data without validating it first.
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[cols="a"]
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|===
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h| Non-compliant code example
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[source,csharp]
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----
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public class Example : Controller
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{
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[HttpPost]
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public ActionResult Deserialize(HttpPostedFileBase inputFile)
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{
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ExpectedType expectedObject = null;
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var formatter = new BinaryFormatter();
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expectedObject = (ExpectedType)formatter.Deserialize(inputFile.InputStream);
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}
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}
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----
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h| Compliant solution
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[source,csharp]
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----
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public class Example : Controller
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{
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[HttpPost]
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public ActionResult Deserialize(HttpPostedFileBase inputFile)
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{
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ExpectedType expectedObject = null;
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JsonSerializer serializer = new JsonSerializer(typeof(expectedObject));
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expectedObject = (ExpectedType)serializer.Deserialize(inputFile.InputStream);
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}
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}
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----
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|===
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=== How does this work?
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include::../../common/fix/introduction.adoc[]
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include::../../common/fix/safer-serialization.adoc[]
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include::../../common/fix/integrity-check.adoc[]
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include::../../common/fix/pre-approved-list.adoc[]
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In the code samples, a pre-approved class is used natively by JsonSerializer to
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validate the class during serialization.
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XmlSerializer also provides this capability. +
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**Note**: The pre-approved class should not tamper with the application's inner
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workings.
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The following native types are considered unsafe because they do not provide
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these capabilities:
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* `BinaryFormatter`
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* `SoapFormatter`
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* `NetDataContractSerializer`
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* `LosFormatter`
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* `ObjectStateFormatter`
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