CA5383: Ensure use secure cookies in ASP.NET Core

Property	Value
Rule ID	CA5383
Title	Ensure use secure cookies in ASP.NET Core
Category	Security
Fix is breaking or non-breaking	Non-breaking
Enabled by default in .NET 9	No

Cause

The Microsoft.AspNetCore.Http.CookieOptions.Secure property may be set as false when invoking Microsoft.AspNetCore.Http.IResponseCookies.Append. For now, this rule only looks at the Microsoft.AspNetCore.Http.Internal.ResponseCookies class, which is one of the implementations of IResponseCookies.

This rule is similar to CA5382, but analysis can't determine that the Secure property is definitely false or not set.

By default, this rule analyzes the entire codebase, but this is configurable.

Rule description

Applications available over HTTPS must use secure cookies, which indicate to the browser that the cookie should only be transmitted using Transport Layer Security (TLS).

How to fix violations

Set Secure property as true under all circumstances.

When to suppress warnings

• If cookies are configured to be secure by default, such as using Microsoft.AspNetCore.CookiePolicy.CookiePolicyMiddleware in Startup.Configure:

  public class Startup
  {
      public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
      {
          app.UseCookiePolicy(
              new CookiePolicyOptions
              {
                  Secure = CookieSecurePolicy.Always
              });
      }
  }
  

• If you're sure there's no sensitive data in the cookies.

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable CA5383
// The code that's violating the rule is on this line.
#pragma warning restore CA5383

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.CA5383.severity = none

For more information, see How to suppress code analysis warnings.

Configure code to analyze

Use the following options to configure which parts of your codebase to run this rule on.

• Exclude specific symbols
• Exclude specific types and their derived types

You can configure these options for just this rule, for all rules it applies to, or for all rules in this category (Security) that it applies to. For more information, see Code quality rule configuration options.

Exclude specific symbols

You can exclude specific symbols, such as types and methods, from analysis. For example, to specify that the rule should not run on any code within types named MyType, add the following key-value pair to an .editorconfig file in your project:

dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType

Allowed symbol name formats in the option value (separated by |):

• Symbol name only (includes all symbols with the name, regardless of the containing type or namespace).
• Fully qualified names in the symbol's documentation ID format. Each symbol name requires a symbol-kind prefix, such as M: for methods, T: for types, and N: for namespaces.
• .ctor for constructors and .cctor for static constructors.

Examples:

Option Value	Summary
dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType	Matches all symbols named MyType.
dotnet_code_quality.CAXXXX.excluded_symbol_names = MyType1|MyType2	Matches all symbols named either MyType1 or MyType2.
dotnet_code_quality.CAXXXX.excluded_symbol_names = M:NS.MyType.MyMethod(ParamType)	Matches specific method MyMethod with the specified fully qualified signature.
dotnet_code_quality.CAXXXX.excluded_symbol_names = M:NS1.MyType1.MyMethod1(ParamType)|M:NS2.MyType2.MyMethod2(ParamType)	Matches specific methods MyMethod1 and MyMethod2 with the respective fully qualified signatures.

Exclude specific types and their derived types

You can exclude specific types and their derived types from analysis. For example, to specify that the rule should not run on any methods within types named MyType and their derived types, add the following key-value pair to an .editorconfig file in your project:

dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType

Allowed symbol name formats in the option value (separated by |):

• Type name only (includes all types with the name, regardless of the containing type or namespace).
• Fully qualified names in the symbol's documentation ID format, with an optional T: prefix.

Examples:

Option Value	Summary
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType	Matches all types named MyType and all of their derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = MyType1|MyType2	Matches all types named either MyType1 or MyType2 and all of their derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = M:NS.MyType	Matches specific type MyType with given fully qualified name and all of its derived types.
dotnet_code_quality.CAXXXX.excluded_type_names_with_derived_types = M:NS1.MyType1|M:NS2.MyType2	Matches specific types MyType1 and MyType2 with the respective fully qualified names, and all of their derived types.

Example

The following snippet illustrates the pattern detected by this rule.

Violation:

using System;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Internal;

class ExampleClass
{
    public void ExampleMethod(string key, string value)
    {
        var cookieOptions = new CookieOptions();
        cookieOptions.Secure = false;
        Random r = new Random();

        if (r.Next(6) == 4)
        {
            cookieOptions.Secure = true;
        }

        var responseCookies = new ResponseCookies(null, null);
        responseCookies.Append(key, value, cookieOptions);
    }
}

Solution:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Internal;

class ExampleClass
{
    public void ExampleMethod(string key, string value)
    {
        var cookieOptions = new CookieOptions();
        cookieOptions.Secure = true;
        var responseCookies = new ResponseCookies(null, null);
        responseCookies.Append(key, value, cookieOptions);
    }
}