Malware first appeared on smartphones in 2004 with worms, viruses, and trojans. Android malware saw major increases from 2010-2011 while iOS malware remained low. Notable Android malware included DroidDream, which infected apps on the Android Market, and fake Angry Birds apps that rooted devices. Plankton is sophisticated Android spyware that collects device information. Possible smartphone attacks include DoS on base stations, DDoS on call centers, remote wiretapping, and SMS spamming. Prevention methods involve app store screening, OS security features, anti-virus software, and user education.