In which attack does an attacker modify web content by entering HTML code?

The attack in which an attacker modifies web content by entering HTML code is best described as a form of cross-site scripting (XSS), which is similar in nature to command injection but specifically focuses on the manipulation of web pages through the injection of scripts. This allows attackers to execute their own code in the context of a user's browser, potentially leading to unauthorized actions or data theft.

In command injection attacks, the focus is on executing arbitrary commands on a server through input fields or other vulnerable points, rather than specifically modifying web content through HTML code. Similarly, directory traversal attacks exploit vulnerabilities that allow attackers to access restricted directories and files outside of the web root, which is distinctly different from altering web page content.

LDAP injection involves manipulating LDAP (Lightweight Directory Access Protocol) queries to gain unauthorized access or modify directory services, but it does not relate directly to modifying web content using HTML.

Flash cookie exploitation refers to a type of attack targeting Adobe Flash storage, mainly focused on retrieving or altering data stored in Flash cookies, rather than manipulating web content with HTML code.

Thus, the nature of the attack that involves modifying web content via HTML code fits best with the characteristics of command injection in the context of web applications, albeit more clearly aligned with cross-site scripting, indicating