Malicious URL is a URL created with malicious purposes, among them, to download any type of malware to the affected computer, which can be contained in spam or phishing messages, or even improve its position in search engines using Blackhat SEO techniques.
Phishing involves sending emails that appear to come from reliable sources (such as banks) and that try to get users to reveal confidential banking information. One of the most widely used tactics is to include a link in the message which, when clicked on, takes users to spoofed web pages. In this way, users, thinking that they are in a trusted site, enter the requested information which is really falling into the hands of the fraudster.
On the other hand, Blackhat SEO refers to the use of SEO (Search Engine Optimization) techniques by cyber-criminals to promote their web pages to improve the positioning of web pages in search engines and lead users to access them.
Malicious URL needs an attacking user's intervention in order to reach the affected computer. The means of distribution used include, among others, spam or phishing messages with links to the malicious site, Blackhat SEO techniques, Internet downloads, peer-to-peer (P2P) file sharing networks, etc.