[WW-3264] Vulnerability of dynamic method invocation

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.1.8
• Fix Version/s: 2.3.1
• Assignee: John Lindal
• Reporter: Alex Siman
• Created: 26/Sep/09 01:50
• Updated: 16/Dec/11 20:29
• Resolved: 09/Jun/11 15:46

Description

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
==================

1. 1. 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"; }

}

Issue Links

• is related to: WW-2363 Allow limiting of action methods
• is related to: WW-3538 Remove Dynamic Method Invocation