A BHO is a small program that extends Microsoft's Internet Explorer. Examples of BHO usage include visible add-on toolbars in Internet Explorer, but can also be hidden functions. Ad- and spyware as well as browser hijackers often use BHOs to display ads or follow your track across the internet, because a BHO has access to each URL you visit and can redirect you or display other pages than you requested (ads, for example).

BHOs often use ActiveX installation programs.

Spybot-S&D is able to display a list of installed browser helper applications. It also has a small database integrated that will display a green checkmark in front of browser helpers known as legitimate, and a red sign in front if applications known as illegitimate. It also allows the user to enable or disable single BHOs.

This list can be exported into a text file as a reference and for further analysis.

Feature added in version 1.3: entries that have changed since the last snapshot (the first snapshot is created when you started Spybot-S&D for the first time, later on you can create snapshots by right-clicking the list and selecting the corresponding menu item) are displayed in bold letters. This allows you to see changes to the list at once.