The Problem

One day on Google search, I noticed that several well-known domestic websites had strange descriptions like the one below.

Curiosity got the better of me, so I opened the browser dev tools.

I checked the title and description in the page header used by search engines for indexing — they matched what Google had indexed.

Questions

From a web developer's perspective, all sorts of doubts came to mind.

Has the site been hacked?

Were hidden links secretly injected?

Or were the admin credentials compromised?

Reproducing the Scenario

I tried tweaking the site's query string by appending "你好測試測試" (hello test test). Sure enough, the title and description in the header changed along with it.

Impact on the Website

According to this article, this is a backlink technique in SEO. When other sites link to yours, search engines treat it as an "endorsement". As your visibility grows and major media or forums increasingly cite your site, you accumulate endorsements from many different sources, and your site's authority climbs. The flip side is that if the linking sites are low-quality, your site's authority can take a hit too.

The Root Cause

After digging through plenty of references, I found that this technique is a form of black hat SEO known as keyword stuffing. Many websites, in their pursuit of better SEO, allow Google's crawler to index user search result pages. Black hat SEO exploits this built-in behavior by stuffing the URLs they want to promote into the query string. The site then adds those user-searched URLs to its sitemap.xml, and Google's crawler eventually picks them up into its search index.

After understanding the issue, I also reported it to those companies' fan pages and employees.

How to Prevent It

• Filter out special keywords
• Build an SEO whitelist/blacklist and a review mechanism
• Don't let unsanitized data flow into the page header's title or description