Final answer:
To defend against both cross-site scripting attacks and SQL injection, Joe should implement filtering of user input, which includes validating and sanitizing data provided by users. This method directly addresses the prevention of the execution of malicious code. While there are other security measures to consider, including stronger passwords and encryption, filtering is the most relevant to the specific attacks mentioned.
Step-by-step explanation:
Joe is concerned about protecting an e-commerce server from a cross-site scripting attack and SQL injection. One effective method to defend against both types of attacks is C) Filtering user input. This involves validating, sanitizing, and escaping user inputs to prevent malicious data from being executed as code. Additionally, cross-site scripting can be mitigated by setting appropriate response headers to enforce the Content Security Policy (CSP), thus preventing the browser from executing unauthorized scripts.
Other actions that Joe can take to increase security, which are not specifically related to preventing cross-site scripting or SQL injections, include the use of two-factor authentication, establishing stronger password policies, and educating users to avoid scams. For the protection of data in transit, using encryption for data transmission is essential, although it does not specifically address the aforementioned attacks.
It's important to note that regularly updating server software while certainly a good security practice, it doesn't inherently filter input to prevent these attacks. Therefore, filtering user input is the option that directly mitigates the risk of cross-site scripting and SQL injection as described in the initial question.