Input Validation

An Input Validation policy can prevent suspicious HTTP requests. This function will verify the user input from scan points like URL parameter, HTML form, hidden fields, and upload file. If the format isn't correct or FortiADC detects other attacks, the request will be blocked.

To configure an Input Validation policy:

1. Go to Web Application Firewall>Input Validation.
2. Click the Parameter Validation tab.

3. Click Create New to display the configuration editor. See Parameter Validation.

   Name	Enter a unique Input Validation policy name. Valid characters are A-Z, a-z, 0-9, _, and -. No space is allowed. Note: Once saved, the name of an Input Validation policy cannot be changed.
   Host Status	Enable to require that the Host: field of the HTTP request match a protected host name's entry in order to match the URL access rule. Also configure Host.
   Host	Select which protected host name's entry (either a web host name or IP address) that the Host: field of the HTTP request must be in to match the URL access rule. Note: Optional. Only available when Host Status is enabled.
   Request URL	The HTTP request URL must be start with /. eg./login. This item must be set when configuring the rule. FortiADC will match the other item (rule) when matching the request URL; if the match fails, FortiADC will not attempt to match others.
   Action	Select which action FortiADC takes when the conditions are fulfilled for Parameter Validation. Alert—Accept the request and generate an alert email, log message, or both. Deny—Block the request (or reset the connection). Block—Block subsequent requests from the client for a number of seconds. Also configure Block Period. Silent-deny—Deny without log. The default value is Alert.
   Severity	When FortiADC records violations of this rule in the attack log, each log message contains a Severity Level (severity_level) field. Select which severity level FortiADC uses when using Input Validation: Low Medium High The default value is Low.

4. Click Save.

5. Edit the newly created Parameter Validation. Under Parameter Validation Rule Element, click Create New.

   Name	Enter a unique Parameter Validation Rule Element name. It must match the value of the name in the input type of the HTML request.
   Max Length	The maximum length of the Parameter Validation Rule Element name's value.

6. Click Save.

7. Click the Hidden Field tab.

8. Click Create New to display the configuration editor. See Hidden Fields.

   Name	Enter a unique Hidden Fields policy name. Valid characters are A-Z, a-z, 0-9, _, and -. No space is allowed. Note: Once saved, the name of a Hidden Field policy cannot be changed.
   Host Status	Enable to require that the Host: field of the HTTP request match a protected host name's entry in order to match the URL access rule. Also configure Host.
   Host	Select which protected host name's entry (either a web host name or IP address) that the Host: field of the HTTP request must be in to match the URL access rule. Note: Optional. Only available when Host Status is enabled.
   Request URL	The HTTP request URL must be start with /. eg./login. This item must be set when configuring the rule. FortiADC will match the other item (rule) when matching the request URL; if the match fails, FortiADC will not attempt to match others.
   Action	Select which action FortiADC takes when the conditions are fulfilled for Hidden Field. Alert—Accept the request and generate an alert email, log message, or both. Deny—Block the request (or reset the connection). Block—Block subsequent requests from the client for a number of seconds. Also configure Block Period. Silent-deny—Deny without log. The default value is Alert.
   Severity	When FortiADC records violations of this rule in the attack log, each log message contains a Severity Level (severity_level) field. Select which severity level FortiADC uses when using Input Validation: Low Medium High The default value is Low.

9. Click Save.

10. Edit the newly created Hidden Field. Under Post URL, click Create New.

    URL	The hidden fields function only works on the configured Post URL.

11. Click Save.

12. Edit the newly created Hidden Field. Under Hidden Fields, click Create New.

    To apply this feature, you must enable Session Management in your protection profile.

    Name	Enter a unique Parameter Validation Rule Element name. It must match the value of the name in the input type of the HTML request.

13. Click Save.
14. Click the File Restriction tab.

15. Click Create New to display the configuration editor. See File Restriction

    Name	Enter a unique File Restriction policy name. Valid characters are A-Z, a-z, 0-9, _, and -. No space is allowed. Note: Once saved, the name of a File Restriction policy cannot be changed.
    Host Status	Enable to require that the Host: field of the HTTP request match a protected host name's entry in order to match the URL access rule. Also configure Host.
    Host	Select which protected host name's entry (either a web host name or IP address) that the Host: field of the HTTP request must be in to match the URL access rule. Note: Optional. Only available when Host Status is enabled.
    Request URL	The HTTP request URL must be start with /. eg./login. This item must be set when configuring the rule. FortiADC will match the other item (rule) when matching the request URL; if the match fails, FortiADC will not attempt to match others.
    Action	Select which action FortiADC takes when the conditions are fulfilled for File Restriction. Alert—Accept the request and generate an alert email, log message, or both. Deny—Block the request (or reset the connection). Block—Block subsequent requests from the client for a number of seconds. Also configure Block Period. Silent-deny—Deny without log. The default value is Alert.
    Severity	When FortiADC records violations of this rule in the attack log, each log message contains a Severity Level (severity_level) field. Select which severity level FortiADC uses when using Input Validation: Low Medium High The default value is Low.
    Upload File Status	Allow: Only allow the selected file type to upload. Block: Block any upload of the selected file type.
    Upload File Size	The maximum size of the uploaded file.

16. Click Save.

17. Edit the newly created File Restriction. Under Upload File Type, click Create New.

    File Type

    The supported file types for the uploaded file.

18. Click save.

19. Go to the Input Validation Policy tab. Click Create New.

    Name	Enter a unique Input Validation policy name. Valid characters are A-Z, a-z, 0-9, _, and -. No space is allowed. Note: Once saved, the name of an Input Validation policy cannot be changed.
    Parameter Validation Rule	The Parameter Validation rule created previously.
    Hidden Field Rule	The Hidden Field rule created previously.
    File Restriction Rule	The File Restriction rule created previously.

20. Click Save. You have successfully created an Input Validation policy.

Parameter Validation

Inputs are typically the <input> tags in an HTML form. Input rules define whether or not parameters are required, and their maximum allowed length. Input rules are for visible inputs only, such as buttons and text areas. This function will do the following:

1. Check HOST by simple string or regular expression matching.
2. Check URL by simple string or regular expression matching.
3. Check the parameter name of inputs filed by matching simple string or regular express. Will also restrict the length of the name.

If the conditions are successfully matched, it will execute the specified action.

Hidden Fields

The Hidden Fields rules are for hidden parameters only, from <input type="hidden"> HTML tags. It is often written into an HTML page by the web server when it serves that page to the client, and isnot visible on the rendered web page. This function will do the following:

1. Check HOST by simple string or regular expression matching .
2. Check URL by simple string or regular expression matching.
3. Match the configuration of the fetched URL.

If the conditions are successfully matched, it will execute the specified action.

File Restriction

The File Restriction rule is for restricting file uploads based on file type and size. This function will do the following:

1. Check HOST by simple string or regular expression matching.
2. Check URL by simple string or regular expression matching .
3. Check the uploaded file type and file size by simple string or regular expression matching.

If the conditions are successfully matched, it will execute the specified action.