The attacks that actually hit small and mid-sized business websites are, almost without exception, well-understood and well-documented. Sophisticated novel exploits make headlines; the boring, automated, well-known attacks are what actually cause most breaches.
SQL injection
An attacker inserts malicious SQL through an input field, tricking your database into running commands it was never meant to. Defense: parameterized queries or an ORM, always — never build SQL by concatenating raw user input into a query string.
Cross-site scripting (XSS)
Malicious script gets injected into a page and runs in another user's browser — often through a comment field, search box, or any place user input gets displayed back without sanitization. Defense: sanitize and encode any user-supplied content before rendering it, and apply a Content Security Policy to limit what scripts are allowed to run at all.
Cross-site request forgery (CSRF)
A malicious site tricks a logged-in user's browser into submitting a request to your site — a password change, a purchase, a settings update — without the user intending it. Defense: CSRF tokens tied to the user's session, verified on every state-changing request.
Brute-force and credential-stuffing attacks
Automated tools try large numbers of password combinations, or reuse credentials leaked from other breaches, against your login form. Defense: rate limiting on login attempts, account lockouts after repeated failures, and multi-factor authentication wherever the account matters.
Distributed denial-of-service (DDoS)
An attacker floods your site with traffic until it can't serve legitimate users. Defense: a CDN or DDoS-mitigation service in front of your origin server, which absorbs and filters malicious traffic before it ever reaches you.
Every attack on this list has a known, well-tested defense. The businesses that get hit are rarely the ones facing something novel — they're the ones that hadn't yet applied the well-known fix.
Man-in-the-middle attacks
An attacker intercepts communication between a user and your server on an insecure network. Defense: HTTPS everywhere, with no exceptions for "less important" pages — a single unencrypted page can leak session cookies for the entire site.
The pattern across all of these
Every one of these defenses is well-established and doesn't require reinventing anything. The real risk isn't a lack of known solutions — it's deploying a site without them, usually because security got treated as a later step instead of a built-in requirement from day one.