Have you ever found that the home page on your browser isn't the one that you specified? Or you type in an address and a completely different page appears? Or pop-up adverts keep appearing when you are surfing the Web? If any of these have happened to you, your browser has been hijacked. But with these hijackers there's no negotiation, and many users even end up reformatting their systems to get them back to normal.
Hijacking browsers is becoming an increasingly common phenomenon, largely due to the financial gain obtained by the perpetrators from unscrupulous marketing agencies. It can be done with specific programs installed on computers from dubious web pages (illegal download pages, underground sites, etc.). These programs then make changes to the system resulting in the browser being hijacked.
These attacks can also involve the use of malicious code -principally Trojans. In effect, this increases the channels through which a browser can be hijacked, as malicious code can spread through email, newsgroups, floppy disks, CD... In any event, no matter how they take control of the browser, the result is nearly always a nightmare experience for the victim.
Given the complexity of the changes that many of these programs or viruses can make to the systems they affect, manual repair of a hijacked browser is extremely difficult. For this reason, taking preventative measures is the best strategy and the most basic of these is to take care with the web pages you visit and avoid downloading from dubious sites.
Using a quality, up-to-date antivirus and installing a firewall to monitor traffic passing through communication ports are strategies that should be considered. It is also wise to stay up-to-date about new vulnerabilities detected that affect the software installed on your computer and apply any corresponding patches. This will prevent any malicious code or programs exploiting these flaws to hijack your Internet browser.
If a browser has been hijacked, there are specific applications on the Internet to resolve this problem. If this doesn't work, a search of newsgroups or forums may come up with information provided by users that have already been through the same situation and managed to survive.