Remove ChumSearch from Safari, Chrome and Firefox on Mac OS XFrom a technical viewpoint, it isn’t difficult to hijack a web browser regardless of the operating system it’s running on. It suffices attackers to force-install an application that intrusively puts certain browsing defaults into effect and doesn’t respond to the infected user’s manual troubleshooting attempts. This is exactly what happens as far as the ChumSearch contamination incidents are concerned.
Source:
Remove ChumSearch from Safari, Chrome and Firefox on Mac OS X