CWE-107: Struts: Unused Validation Form

What is Struts: Unused Validation Form?

• Overview: This vulnerability occurs when a Struts application contains validation forms that are no longer in use, usually because the associated action form mappings have been removed or renamed, leading to outdated validation logic.

• Exploitation Methods:

• Attackers can exploit this by targeting areas of the application that lack proper validation, potentially bypassing security checks.
• Common attack patterns include injecting malicious inputs or exploiting weak spots where validation is inadequate or missing.

• Security Impact:

• Direct consequences include unauthorized access, data manipulation, or application crashes due to unchecked input.
• Potential cascading effects might involve further exploitation of the system through privilege escalation.
• Business impact could involve data breaches, loss of customer trust, regulatory fines, or operational disruptions.

• Prevention Guidelines:

• Specific code-level fixes include regularly reviewing and updating validation logic to ensure all forms are accounted for and no unused validation remains.
• Security best practices involve maintaining comprehensive and up-to-date documentation of form mappings and validation logic.
• Recommended tools and frameworks include using automated testing and validation tools to identify unused validation forms and employing static code analysis to detect discrepancies in validation logic.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Java

Affected Technologies: Not specified

Vulnerable Code Example

// Vulnerable code: Unused validation form fields in a Struts application

public class MyActionForm extends org.apache.struts.action.ActionForm {
    // Unused validation fields can lead to potential security vulnerabilities
    private String phoneNumber; // Unused field
    private String email; // Unused field

    private String userName;
    private String password;

    // Getters and setters for the unused fields
    public String getPhoneNumber() { return phoneNumber; }
    public void setPhoneNumber(String phoneNumber) { this.phoneNumber = phoneNumber; }
    
    // Getters and setters for the actual fields used in validation
    public String getUserName() { return userName; }
    public void setUserName(String userName) { this.userName = userName; }
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
}

In this vulnerable code example, the phoneNumber and email fields are defined in the MyActionForm class but are not used in any validation logic. This can lead to security issues as it might indicate incomplete validation, leading to unchecked input that could be exploited.

How to fix Struts: Unused Validation Form?

Unused validation forms in a Struts application can lead to security vulnerabilities because they may indicate outdated or incorrect validation logic. This can result in unchecked input being processed, potentially leading to injection attacks or other forms of data corruption.

To fix this, ensure that all fields defined in the form are actively used in validation logic. Remove any unused fields to prevent confusion and ensure that the validation logic is accurate and comprehensive. This also reduces the attack surface by ensuring only necessary data is processed.

Fixed Code Example

// Fixed code: Removed unused validation fields

public class MyActionForm extends org.apache.struts.action.ActionForm {
    // Removed unused fields phoneNumber and email

    private String userName;
    private String password;

    // Getters and setters for the actual fields used in validation
    public String getUserName() { return userName; }
    public void setUserName(String userName) { this.userName = userName; }
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
}

In the fixed code, the phoneNumber and email fields have been removed from the MyActionForm class, as they were not involved in any validation logic. This cleanup ensures that only the necessary fields (userName and password) are present in the form, making the application more secure and maintainable. Removing unused fields helps prevent potential security vulnerabilities by ensuring that all input is properly validated.