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Posted to issues@struts.apache.org by "Alex Siman (JIRA)" <ji...@apache.org> on 2009/10/12 22:23:50 UTC

[jira] Commented: (WW-3264) Vulnerability of dynamic method invocation

    [ https://issues.apache.org/struts/browse/WW-3264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=46916#action_46916 ] 

Alex Siman commented on WW-3264:
--------------------------------

Seems like this is old feature request:

> Vulnerability of dynamic method invocation
> ------------------------------------------
>
>                 Key: WW-3264
>                 URL: https://issues.apache.org/struts/browse/WW-3264
>             Project: Struts 2
>          Issue Type: Bug
>    Affects Versions: 2.1.8
>            Reporter: Alex Siman
>            Priority: Critical
>             Fix For: 2.1.9
>
>
> Dynamic method invocation is the security hole. If some of action methods has "public" visibility and return String, then attacker can call this method. In the example below, attacker can call method "changeAdminPassword()" of TestAction from URL like:
> http://example.com/test!changeAdminPassword.action
> public class TestAction
> {
>     private String currentPassword = null;
>     @SkipValidation
>     public String execute() throws Exception
>     {
>         if (getValidCurrentPassword().equals(currentPassword))
>         {
>             String feedback = changeAdminPassword();
>             addActionMessage(feedback);
>             return SUCCESS;
>         }
>         else
>         {
>             addFieldError("currentPassword", "Invalid password.");
>             return INPUT;
>         }
>     }
>     // Note "public" visibility here.
>     public String changeAdminPassword()
>     {
>         String newPassword = "new-admin";
>         // Persist changes here...
>         return "Admin password has been changed to '" + newPassword + "'.";
>     }
>     
>     public String getCurrentPassword()
>     {
>         return currentPassword;
>     }
>     public void setCurrentPassword(String currentPassword)
>     {
>         this.currentPassword = currentPassword;
>     }
> }
> To fix this vulnerability we must leverage the [com.opensymphony.xwork2.config.entities.ActionConfig.allowedMethods].
> And to prevent backward incompatibility add new default setting like:
> default.properties
> ==================
> ## Note "false".
> struts.enable.DynamicMethodInvocation.restrictToAllowedMethods = false
> Desired code in struts.xml
> ==========================
> <package name="testPackage">
>     <action name="login" class="actions.LoginAction">
>         <result>/login.jsp</result>
>         <allowedMethods>
>             <allowedMethod>doLogin</allowedMethod>
>         </allowedMethods>
>     </action>
>     <allowedMethods class="actions.LoginAction">
>         <allowedMethod>doLogin</allowedMethod>
>         <allowedMethod>doRegister</allowedMethod>
>     </allowedMethods>
>     <!— Or use <method>? -->
>     <allowedMethods class="actions.UserAction">
>         <method>create</method>
>         <method>list</method>
>         <method>view</method>
>         <!-- ... -->
>     </allowedMethods>
> </package>
> Desired code w/ Convention plugin:
> (Note @AllowedMethod anno)
> ==================================
> class LoginAction 
> {
>     @SkipValidation
>     public String execute()
>     {
>         // Nothing.
>         return INPUT;
>     }
>     @AllowedMethod
>     public String doLogin()
>     {
>         // Method's body here...
>         // password = getPasswordHash();
>         return SUCCESS;
>     }
>     // This method cannot be invoked dynamically.
>     public String getPasswordHash()
>     {
>         // Method's body here...
>         return "xxx";
>     }
> }

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