CA2122: Do not indirectly expose methods with link demands







Breaking Change

Non Breaking


A public or protected member has a Link Demands and is called by a member that does not perform any security checks.

Rule Description

A link demand checks the permissions of the immediate caller only. If a member X makes no security demands of its callers, and calls code protected by a link demand, a caller without the necessary permission can use X to access the protected member.

How to Fix Violations

Add a security Data Access and Modeling or link demand to the member so that it no longer provides unsecured access to the link demand-protected member.

When to Suppress Warnings

To safely suppress a warning from this rule, you must make sure that your code does not grant its callers access to operations or resources that can be used in a destructive manner.


The following examples show a library that violates the rule, and an application that demonstrates the library's weakness. The sample library provides two methods that together violate the rule. The EnvironmentSetting method is secured by a link demand for unrestricted access to environment variables. The DomainInformation method makes no security demands of its callers before it calls EnvironmentSetting.

using System;
using System.IO;
using System.Security;
using System.Security.Permissions;

namespace SecurityRulesLibrary
   public class DoNotIndirectlyExposeMethodsWithLinkDemands
      // Violates rule: DoNotIndirectlyExposeMethodsWithLinkDemands.
      public static string DomainInformation()
         return EnvironmentSetting("USERDNSDOMAIN");

      // Library method with link demand.
      // This method holds its immediate callers responsible for securing the information.
      // Because a caller must have unrestricted permission, the method asserts read permission
      // in case some caller in the stack does not have this permission. 

      [EnvironmentPermissionAttribute(SecurityAction.LinkDemand, Unrestricted=true)]
      public static string EnvironmentSetting(string environmentVariable)
         EnvironmentPermission envPermission = new EnvironmentPermission( EnvironmentPermissionAccess.Read,environmentVariable);

         return Environment.GetEnvironmentVariable(environmentVariable);

The following application calls the unsecured library member.

using System;
using SecurityRulesLibrary;
using System.Security;
using System.Security.Permissions;

// You have no permission to access the sensitive information,
// but you will get data from the unprotected method.
namespace TestUnsecuredMembers
   class TestUnsecured
      static void Main(string[] args)
         string value = null;
            value = DoNotIndirectlyExposeMethodsWithLinkDemands.DomainInformation();
         catch (SecurityException e) 
               "Call to unsecured member was stopped by code access security! {0}",
         if (value != null) 
            Console.WriteLine("Value from unsecured member: {0}", value);

This example produces the following output.

Value from unsecured member:

See Also


Link Demands

Other Resources

Secure Coding Guidelines

Data Access and Modeling