Input Validation for Web Forms CASENET Practice Questions (Page 5)

Questions 21–25

1. 21application · medium

   An e-commerce application has a search form that takes a product name and displays matching results. A penetration test revealed that submitting the string `' OR '1'='1` in the search field returns all products in the database. The application uses parameterized queries for the search. Which additional vulnerability is most likely present?

   • AThe application is vulnerable to SQL injection because parameterized queries are not sufficient.
   • BThe application is reflecting the search term without proper output encoding, leading to reflected XSS.
   • CThe application is vulnerable to LDAP injection because the search term is used in an LDAP query.
   • DThe application is vulnerable to command injection because the search term is passed to a system command.
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2. 22application · medium

   A web application has a form field for a user's age. The requirement is to accept only integers between 18 and 99. The current implementation uses a blacklist that rejects the string 'DROP TABLE' and other SQL keywords. Which of the following is the most secure approach to validate this field?

   • AConvert the input to an integer and check if it is between 18 and 99, but do not use a regular expression.
   • BUse a RangeValidator control with MinimumValue=18 and MaximumValue=99.
   • CKeep the blacklist but add more SQL keywords to it.
   • DUse a RegularExpressionValidator with the pattern `^(1[89]|[2-9][0-9])$` and also validate the range on the server.
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4. 23foundation · easy

   Which validation approach is generally more secure for validating user input?

   • AWhitelist validation, because it only accepts known good input.
   • BBlacklist validation, because it blocks known bad patterns.
   • CBlacklist validation, because it is easier to implement.
   • DBoth are equally secure.
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5. 24foundation · easy

   A web form accepts a username and displays it on a profile page. If the input is not validated or encoded, which vulnerability is most likely to occur?

   • ALDAP injection
   • BCommand injection
   • CSQL injection
   • DCross-site scripting (XSS)
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6. 25expert · hard

   A security review of an ASP.NET application reveals that a registration form has client-side validation using JavaScript, but no server-side validation. The form includes fields for username, email, and password. An attacker can bypass the client-side validation and submit malicious data directly to the server. Which combination of actions should the developer take to mitigate the risk?

   • AEncode all user input with HttpUtility.HtmlEncode before storing it in the database.
   • BAdd more complex client-side validation using regular expressions to block malicious input before it reaches the server.
   • CImplement server-side validation for all fields, including format checks and length limits, and use parameterized queries for any database operations.
   • DUse ASP.NET validation controls with EnableClientScript set to true, and rely on them to validate on the server automatically.
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