Comodo recently cleaned some malware for me but said I needed to do this to secure the site:
We found some vulnerability on your domain listed below, these may lead the attacker to enter your domain.
i) Missing HTTP security headers
X-Frame-Options-Protects against Clickjacking attacks Not set
X-XSS-Protection-Mitigates Cross-Site Scripting (XSS) attacks Not set
Strict-Transport-Security-Protects against man-in-the-middle attacks Not set
X-Content-Type-Options-Prevents possible phishing or XSS attacks Not set
How should I add these?