Kevin sends an email invite to Chris to visit a forum for security professionals. Chris clicks on the link in the email message and is taken to a web based bulletin board. Unknown to Chris, certain functions are executed on his local system under his privileges, which allow Kevin access to information used on the BBS. However, no executables are downloaded and run on the local system. What would you term this attack?

A.
Phishing

B.
Denial of Service

C.
Cross Site Scripting

D.
Backdoor installation

Explanation:
This is a typical Type-1 Cross Site Scripting attack. This kind of cross-site scripting hole is also referred to as a non-persistent or reflected vulnerability, and is by far the most common type. These holes show up when data provided by a web client is used immediately by server-side scripts to generate a page of results for that user. If unvalidated user-supplied data is included in the resulting page without HTML encoding, this will allow client-side code to be injected into the dynamic page. A classic example of this is in site search engines: if one searches for a string which includes some HTML special characters, often the search string will be redisplayed on the result page to indicate what was searched for, or will at least include the search terms in the text box for easier editing. If all occurrences of the search terms are not HTML entity encoded, an XSS hole will result.