Struts: Unused Validation Form

An unused validation form indicates that validation logic is not up-to-date.


Description

It is easy for developers to forget to update validation logic when they remove or rename action form mappings. One indication that validation logic is not being properly maintained is the presence of an unused validation form.

Demonstrations

The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

In the following example the class RegistrationForm is a Struts framework ActionForm Bean that will maintain user input data from a registration webpage for an online business site. The user will enter registration data and, through the Struts framework, the RegistrationForm bean will maintain the user data in the form fields using the private member variables. The RegistrationForm class uses the Struts validation capability by extending the ValidatorForm class and including the validation for the form fields within the validator XML file, validator.xml.

public class RegistrationForm extends org.apache.struts.validator.ValidatorForm {



  // private variables for registration form
  private String name;
  private String address;
  private String city;
  private String state;
  private String zipcode;
  // no longer using the phone form field

  // private String phone;
  private String email;

  public RegistrationForm() {
    super();
  }

  // getter and setter methods for private variables
  ...

}
<form-validation>

  <formset>

    <form name="RegistrationForm">

      <field property="name" depends="required">
        <arg position="0" key="prompt.name"/>
      </field>
      <field property="address" depends="required">
        <arg position="0" key="prompt.address"/>
      </field>
      <field property="city" depends="required">
        <arg position="0" key="prompt.city"/>
      </field>
      <field property="state" depends="required,mask">
        <arg position="0" key="prompt.state"/>
        <var>
          <var-name>mask</var-name>
          <var-value>[a-zA-Z]{2}</var-value>
        </var>
      </field>
      <field property="zipcode" depends="required,mask">
        <arg position="0" key="prompt.zipcode"/>
        <var>
          <var-name>mask</var-name>
          <var-value>\d{5}</var-value>
        </var>
      </field>
      <field property="phone" depends="required,mask">
        <arg position="0" key="prompt.phone"/>
        <var>
          <var-name>mask</var-name>
          <var-value>^([0-9]{3})(-)([0-9]{4}|[0-9]{4})$</var-value>
        </var>
      </field>
      <field property="email" depends="required,email">
        <arg position="0" key="prompt.email"/>
      </field>

    </form>

  </formset>

</form-validation>

However, the validator XML file, validator.xml, for the RegistrationForm class includes the validation form for the user input form field "phone" that is no longer used by the input form and the RegistrationForm class. Any validation forms that are no longer required should be removed from the validator XML file, validator.xml.

The existence of unused forms may be an indication to attackers that this code is out of date or poorly maintained.

See Also

SFP Secondary Cluster: Tainted Input to Command

This category identifies Software Fault Patterns (SFPs) within the Tainted Input to Command cluster (SFP24).

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses without Software Fault Patterns

CWE identifiers in this view are weaknesses that do not have associated Software Fault Patterns (SFPs), as covered by the CWE-888 view. As such, they represent gaps in...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.


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