Unfortunately, it looks like people who want to maliciously attack smartphone users are increasing their efforts, particularly on Android users. Last month Google removed 25 apps from the Android Market that had malware called Droid Dream Light. In their latest efforts, the malware developers are bypassing the Android Market by providing a web site that looks very much like the official market in hopes to fool users into installing the malware-infected apps directly from the web site.
By default, Android is configured to only allow installation of apps from the Android Market. However, that configuration can easily be changed, and worse, many users have been enticed into making the change and instructed in how to do so by Amazon thanks to Amazon’s free app of the day. In order to use the Amazon Appstore and get those free apps that Amazon is providing, you have to configure Android to allow the installation of apps from Unknown Sources by tapping Menu, Settings, Applications.
If you are really concerned about getting your Android phone infected with malware or other malicious software, you should only install apps from the Android Market and keep Android configured to not allow installation of apps from Unknown Sources. If you really prefer to use the Amazon Appstore then limit yourself to only installing apps from the Appstore or the Android Market, and pay attention to what you are doing to be sure you are not installing an app via a think from a web site in the Android web browser.