Google is getting better at keeping Android malware out of the Play Store, and that's leading attackers to use more sophisticated disguises for their rogue apps. SophosLabs has proof: it just detailed a recent ad-spawning malware strain, Andr/HiddnAd-AJ, that slipped into Google Play through innocent-looking QR code and compass apps. While that's nothing new by itself, the malware used a pair of tricks to feign innocence. The hostile code was buried in what looked like a regular Android programming library, and it didn't kick in until 6 hours after you've installed it.