CA5382: Use secure cookies in ASP.NET Core

#Cause

The Microsoft.AspNetCore.Http.CookieOptions.Secure property is 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 Microsoft.AspNetCore.Http.IResponseCookies.

This rule is similar to CA5383, but analysis can determine that the Microsoft.AspNetCore.Http.CookieOptions.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 Microsoft.AspNetCore.Http.CookieOptions.Secure property as true.

#When to suppress warnings

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

  csharpCopy

  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 CA5382
// The code that's violating the rule is on this line.
#pragma warning restore CA5382

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

[*.{cs,vb}]
dotnet_diagnostic.CA5382.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 they apply to, or for all rules in this category (Security) that they apply 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 by setting the excluded_symbol_names option. 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:

#Exclude specific types and their derived types

You can exclude specific types and their derived types from analysis by setting the excluded_type_names_with_derived_types option. 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:

#Example

The following snippet illustrates the pattern detected by this rule.

Violation:

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;
        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);
    }
}