Browser Helper Object (BHO)

A Browser Helper Object (BHO) is a DLL that loads every time Microsoft Internet Explorer runs. Typically, a BHO is installed by a third party program to enhance the functionality of the web browser (many Internet Explorer plugins, for example, are BHOs). BHOs can be installed silently, or can be installed ‘quietly’ (many users fail to read the small print that comes with the EULA (End User License Agreement) displayed by the freeware program). Also, because they’re programs, they can do anything that other programs can do. On top of this, there’s no easy way to list the BHOs installed on the PC. As a result, BHO functionality can be misused (to install adware or track browsing habits, for example).