About spam blogs
As with many powerful tools, blogging services can be both used and abused. The ease of creating and updating webpages with Blogger has made it particularly prone to a form of behavior known as link spamming. Blogs engaged in this behavior are called spam blogs, and can be recognized by their irrelevant, repetitive, or nonsensical text, along with a large number of links, usually all pointing to a single site.
Spam blogs cause various problems, beyond simply wasting a few seconds of your time when you happen to come across one. They can clog up search engines, making it difficult to find real content on the subjects that interest you. They may scrape content from other sites on the web, using other people's writing to make it look as though they have useful information of their own. And if an automated system is creating spam posts at an extremely high rate, it can impact the speed and quality of the service for other, legitimate users.
If your site has been infected, it is generally because some vulnerability has allowed a hacker to take control of your site. The hacker may change the content of the site (for example, to add spam), or add additional pages to the site, usually with the intent of phishing (tricking users into parting with personal and credit card information). Alternatively, they may inject malicious code (malware)—for example, scripts or iFrames that pull content from another website that tries to attack any computer that views the page.
The term "malware" covers all sorts of malicious software designed to harm a computer or network. Kinds of malware include (but are not limited to) viruses, worms, spyware, and Trojan horses. Once a site or computer has been compromised, it can be used to host malicious content such as phishing sites (sites designed to trick users into parting with personal and credit card information). Some hackers may even take administrative control over a hacked site.