The PCAP file shows that the attacker is attempting to exploit a Cross-Site Scripting (XSS) vulnerability on the victim machine. XSS is a type of vulnerability that allows an attacker to inject malicious code into a web application. This malicious code can then be executed by the victim when they visit the web application.
In this case, the attacker is attempting to inject the following malicious code into the web application:
<script> alert ("Click here for important information regarding your account!
http://externalip.com/account.php"); </script>
This code will create a pop-up window that prompts the victim to click on a link. When the victim clicks on the link, they will be redirected to the attacker's website. The attacker can then use this website to steal the victim's personal information or to install malware on the victim's machine.
To prevent future attacks of this type, the security administrator should implement a host-based firewall rule to block traffic from the attacker's IP address. This will prevent the attacker from being able to communicate with the victim machine.