Do you remember the bad old days of computer viruses so invasive that it was easier to nuke your software and start over than fix the problem? They're back... in mobile form. Lookout has noticed a trend toward Android malware that masquerades as a popular app, but quietly gets root-level access to your phone and buries itself deep in the operating system. If that happens, you're in serious trouble. Unless you can walk through loading a fresh ROM or carefully modify system files over ADB, it may be easier to just replace the device, or have your phone company reflash it -- a simple factory reset won't get the job done. Some of the bogus apps are little more than shells for ads, but others will work properly while they compromise your device.