Form Field manipulation is an attack in which an attacker modifies the input fields of a web form. This can be done by altering the structure or content of the form or by injecting malicious code into the form that the server or client executes.

Form Field Manipulation attacks can be used for various purposes, such as bypassing security controls, stealing sensitive data, or gaining unauthorized access to a system. They are often combined with other types of attacks, such as cross-site scripting or SQL injection.

An attacker might try to alter a form field that is used to authenticate a user to gain access to a system. They might do this by changing the name of the field, the type of input that is accepted, or the value that is submitted.

Another common form of Form Field Manipulation is injection attacks, in which the attacker injects malicious code into a form field. This code can then be executed by the server or client, potentially allowing the attacker to gain access to sensitive data or perform other unauthorized actions.

How do Form Field Manipulation attacks work?

Hackers can manipulate form fields to alter the data sent to a web server. They learn about your form field data by studying the source code on your web page. Anyone can do this by right-clicking on a page and choosing “view source code.” The HTML code includes your form field data, which skilled hackers can manipulate using injection attacks and other techniques.

Once the hacker has viewed your source code, he only needs to copy it into a separate file, alter the parameters, and run it in the browser. The Open Web Application Security Project (OWASP) provides an example of a form from an e-commerce site using a hidden field:

<input type=”hidden” id=”1008” name=”cost” value=”70.00”>

The hacker just needs to change 70 to 7 to get a 90 percent discount. All programmers should be aware of this simple hack by now. Besides changing values, hackers can also insert code using SQL injection. provides an excellent example of this technique:

Original code

<input type=”hidden” name=”username” value=”Joe User” >

Revised code

“> <script>alert(document.cookie)</script> <a name =”
The hacker changed the code by including an HTML tag that closed the parameter and pointed to a script.
“> <script>alert(document.cookie)</script> <a name =”

Instead of simply accepting a username, the code now runs an injected script.

How do you prevent Form Field Manipulation attacks?

To prevent Form Field Manipulation attacks, it is important to properly validate and sanitize user input to ensure that it is safe and appropriate. This can be done using techniques such as input validation and output encoding. In addition, it is important to regularly update software and applications to ensure they are secure and free of vulnerabilities.

Several technologies and practices can be used to prevent Form Field manipulation attacks:

  1. Input validation: Input validation is the process of checking user input to ensure that it is safe and appropriate. This can be done using techniques such as data type checking, range checking, and regular expression matching.
  2. Output encoding: Output encoding is the process of converting user input into a safe format before it is displayed or stored. This can help to prevent injection attacks, in which malicious code is injected into a form field and executed by the server or client.
  3. Encryption: Encrypting sensitive data can help to protect it from being accessed or modified by unauthorized parties. This can be especially important for form fields that contain sensitive information such as passwords or credit card numbers.
  4. Regular software updates: Regularly updating software and applications can help ensure they are secure and free of vulnerabilities. This can help to prevent Form Field manipulation attacks that exploit known vulnerabilities in outdated software.
  5. Security awareness training: Providing security awareness training to users can help to educate them about the importance of security and the potential risks of Form Field manipulation attacks. This can help to reduce the likelihood of successful attacks.

By implementing these technologies and practices, organizations and individuals can help to protect themselves against Form Field Manipulation attacks and other types of threats.