Lenovo has been preinstalling adware (called “Superfish”) and a compromised security certificate on laptops. The compromised certificate allows Superfish to perform a “Man-In-The-Middle” attack on any internet connection secured by SSL/TLS, allowing capturing of confidential information like bank accounts and passwords.
Lenovo’s user forum:
https://forums.lenovo.com/t5/Lenovo-P-Y-and-Z-series/Lenovo-Pre-instaling-adware-spam-Superfish-powerd-by/td-p/1726839
thenextweb.com article:
http://thenextweb.com/insider/2015/02/19/lenovo-caught-installing-adware-new-computers/
https://news.ycombinator.com/item?id=9072424
A twitter user has created a fake (usable) certificate for Bank of America:
https://twitter.com/kennwhite/status/568270748638318593/photo/1
It appears only Google’s Chrome and Microsoft’s Internet Explorer are affected: Firefox uses its own certificate chain.