In which of the following methods does an hacker use packet sniffing to read network traffic between two parties to steal the session cookies?

Cross-site scripting injects malicious client-side scripts into web pages to steal cookies via the browser's DOM, not through network packet sniffing.

Physical accessing refers to gaining unauthorized physical access to hardware or devices, not to intercepting network traffic.

Session fixation forces a victim to authenticate using a session ID already known to the attacker, which does not involve packet sniffing.

Session sidejacking specifically involves capturing session tokens by sniffing unencrypted HTTP traffic between a client and server. The attacker does not need credentials - they simply replay the stolen cookie to impersonate the authenticated user. This is distinct from other session attacks because it relies entirely on passive or active network interception.