Majority of web app pentesting is focused on back end components but it is also important to test front end components.
Sensitive Data Exposure - Availability of sensitive data in clear-text to end user.
They are usually found in the source code
.
One of the first thing we do when assessing a web app is to review the source code.
Example
<form action="action_page.php" method="post">
<div class="container">
<label for="uname"><b>Username</b></label>
<input type="text" required>
<label for="psw"><b>Password</b></label>
<input type="password" required>
<!-- TODO: remove test credentials test:test -->
<button type="submit">Login</button>
</div>
</form>
</html>