Microsoft employee Ben Rudolph recently tweeted that any Android phone owner who has a device infected with malware can tweet his or her story with the hashtag #windowsphone upgrade for a chance to win a free Windows Phone. That sounds like an attractive promotion, especially given Microsoft’s fresh batch of powerful and solid Windows Phone 7.5 (Mango) devices. Google has reportedly pulled more than 100 malware applications from the Android Market but Microsoft isn’t exactly an anti-malware poster boy itself. In fact, earlier on Tuesday WinRumors posted a story about a security flaw that allows a user to send a text message that automatically reboots any Windows Phone device and then renders the messaging client completely useless. Microsoft hasn’t yet responded to the report and WinRumors, rightly, didn’t explain exactly how the flaw works. A video of the Windows Phone flaw follows after the break.