--- title: "Analyzing How Black Hat SEO Keyword Stuffing Hit Several Well-Known Websites" description: "An analysis of how several well-known domestic websites were attacked by black hat SEO keyword stuffing: attackers injected content via the query string to manipulate the title and description, causing Google to index unwanted content. Includes preventive measures." canonical_url: "https://blog.markkulab.net/en/post/seo-external-link" author: "Mark Ku" author_url: "https://blog.markkulab.net/en/author/mark-ku" site: "Mark Ku's Tech Notes" date_published: "2022-03-25 01:01:01 +0800" category: "SEO" tags: ["seo", "black hat", "keyword stuffing", "query string", "security", "google"] language: "en" license: "CC BY 4.0" license_url: "https://creativecommons.org/licenses/by/4.0/" attribution: "when reusing or quoting, credit the author and link back to the original" --- # Analyzing How Black Hat SEO Keyword Stuffing Hit Several Well-Known Websites ## The Problem ### One day on Google search, I noticed that several well-known domestic websites had strange descriptions like the one below. ![Google search result showing black hat SEO keyword stuffing](https://blog.markkulab.net/content/markku/posts/seo-external-link/images/xL2V0cF.png) ## 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. ![HTML title and description showing black hat SEO keyword stuffing](https://blog.markkulab.net/content/markku/posts/seo-external-link/images/JaqXIzN.png) ## 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. ![HTML head code showing keyword-stuffed title and description meta tags](https://blog.markkulab.net/content/markku/posts/seo-external-link/images/a8bF5iO.png) ## Impact on the Website According to [this article](https://ranking.works/%E6%8A%80%E8%A1%93SEO/%E5%A4%96%E9%83%A8%E9%80%A3%E7%B5%90?fbclid=IwAR3-2880GtK_3dEp2SUrlhD0t8jHb-_aLHYTCcgWCxI9Vpo55UTni8uZauo), 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](https://baike.baidu.hk/item/%E9%97%9C%E9%8D%B5%E8%A9%9E%E5%A0%86%E7%A0%8C). 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 --- ## About this article and its author Originally published on [Mark Ku's Tech Notes](https://blog.markkulab.net/en/post/seo-external-link) License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) — when reusing or quoting, credit the author and link back to the original ### About the author **[Mark Ku](https://blog.markkulab.net/en/author/mark-ku)** — Software Solution Provider - 10+ years senior software engineer, now an AI Builder - Focused on large-platform architecture — North-American e-commerce, AI SaaS subscription billing - Combining AI Agents and automation to build evolvable product foundations ### Free tools built by the author All of these are free to use: - [Free PDF Sign Tool](https://blog.markkulab.net/en/tools/pdf-sign): Online PDF sign tool — draw, type, or upload a signature, then drag, resize, and download. 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