Are webmalwares capbale of performing browser hijacking attacks ? Has there been any famous webmalware that functioned this way ?
About 10 years ago, browser hijacking attacks by drive-by downloads were extremely frequent. One of the most famous malwares of this kind was CoolWebSearch, named after the web startpage it set on the infected system (which was in fact one of the more harmless "features" it had). But this malware is just one example of many. Often, a system could be infected just by visiting an infected website with a vulnerable web browser.
The majority of these hijackers targeted vulnerabilities in a Windows program called Internet Explorer*. The reason MSIE was so vulnerable back then was because Microsoft wasn't really taking security as serious as they do today. Also, those security patches they released had to be installed manually by the user, which most users didn't do.
However, in the past few years Microsoft started to take security and patch management a lot more serious. Internet Explorer is now updated automatically (just like most other browsers) so the number of users vulnerable to patched vulnerabilities went down dramatically. As a result, browser hijackers became a lot less frequent. However, they haven't died out completely.
*) The tool you run after a Windows installation to download a web browser.