First, the BHO is tied to the browser's main window.

首先，BHO对象依托于浏览器主窗口。

youdao

Any instance of the BHO lives and dies with the browser's instance.

任何BHO对象与浏览器实例的生命周期是一致的。

youdao

method is where the BHO is initialized and where you would perform all the tasks that happen only once.

SetSite()方法正是BHO对象被初始化的地方，此外，在这个方法中你可以执行所有的仅仅允许发生一次的任务。

youdao

"The initial program installed itself as a browser helper object (BHO) for Internet Explorer that downloaded a component from childhe.com and attempted to trick the victim into installing a fake anti-virus scanner from bestantispyware securityscan.com and protectionsoft warecheck.com, " he explained.

BBC: Hackers website