Malware is increasingly popping up on Android devices, so think twice before you download apps from unregulated, third-party Android markets.

Security-software publisher Symantec Corp. has discovered two versions of an app called Steamy Window—one legitimate and one that contains malware. Steamy Window makes the screen on your device look like it's all steamed up, and when you wipe your finger across it, the steam clears.

But a malicious version of the app sold on third-party markets has added functionality you don't want: It sends text messages from the infected phone without your knowledge, adds bookmarks to the browser, blocks text message responses, and installs applications. Symantec says the goal of the malicious app is to build a botnet, but it's also costing users money—and earning the hackers commissions—by texting to premium-rate numbers, according to Computerworld.