Prevent Deserialization Injection

Why this matters

Deserializing untrusted data can allow attackers to execute arbitrary code. Always validate and sanitize serialized inputs before processing.

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        var formatter               = new BinaryFormatter();
        expectedObject              = (ExpectedType)formatter.Deserialize(inputFile.InputStream);
    }
}

Prefer

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        JsonSerializer serializer   = new JsonSerializer(typeof(expectedObject));
        expectedObject              = (ExpectedType)serializer.Deserialize(inputFile.InputStream);
    }
}

More snippets

Bad

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        var formatter               = new BinaryFormatter();
        expectedObject              = (ExpectedType)formatter.Deserialize(inputFile.InputStream);
    }
}

Good

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        JsonSerializer serializer   = new JsonSerializer(typeof(expectedObject));
        expectedObject              = (ExpectedType)serializer.Deserialize(inputFile.InputStream);
    }
}

Related rules

From the same buckets as this rule.

Critical

Always sanitize user inputs

Check if user inputs are sanitized before being used in rendering or database queries. Unsanitized inputs can lead to injection vulnerabilities like XSS or SQL injection.

security-hardening

Critical

Always Verify Server Certificates in SSL/TLS Connections

Ensure that SSL/TLS certificate validation is always enabled to prevent Man-in-the-Middle (MitM) attacks.

security-hardening

Critical

Avoid modifying built-in prototypes

Detect modifications to built-in prototypes. Modifying built-in objects can lead to compatibility issues and unexpected behavior. Recommend creating helper functions instead.

maintainabilitysecurity-hardening

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        var formatter               = new BinaryFormatter();
        expectedObject              = (ExpectedType)formatter.Deserialize(inputFile.InputStream);
    }
}

Prefer

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        JsonSerializer serializer   = new JsonSerializer(typeof(expectedObject));
        expectedObject              = (ExpectedType)serializer.Deserialize(inputFile.InputStream);
    }
}

More snippets

Bad

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        var formatter               = new BinaryFormatter();
        expectedObject              = (ExpectedType)formatter.Deserialize(inputFile.InputStream);
    }
}

Good

public class Example : Controller
{
    [HttpPost]
    public ActionResult Deserialize(HttpPostedFileBase inputFile)
    {
        ExpectedType expectedObject = null;
        JsonSerializer serializer   = new JsonSerializer(typeof(expectedObject));
        expectedObject              = (ExpectedType)serializer.Deserialize(inputFile.InputStream);
    }
}

Related rules

From the same buckets as this rule.

Critical

Always sanitize user inputs

Check if user inputs are sanitized before being used in rendering or database queries. Unsanitized inputs can lead to injection vulnerabilities like XSS or SQL injection.

security-hardening

Critical

Always Verify Server Certificates in SSL/TLS Connections

Ensure that SSL/TLS certificate validation is always enabled to prevent Man-in-the-Middle (MitM) attacks.

security-hardening

Critical

Avoid modifying built-in prototypes

Detect modifications to built-in prototypes. Modifying built-in objects can lead to compatibility issues and unexpected behavior. Recommend creating helper functions instead.

maintainabilitysecurity-hardening