Hijacking QR codes

Just finished printing my poster for a school project in which contained a QR code for users to download an android app. It was my first time printing out 300dpi@A1 size and thankfully it turned out well (A reprint would have cost $12). Anyway, that is beside the point.

More importantly, the QR code was printed at high resolution(300dpi) which is similar to posters/adverts in public places. Assuming that I printed it on "sticker paper", there is nothing stopping me from pasting it over existing QR codes on adverts and posters. If the size is similar and pasting was done well, it is almost indistinguishable.

What could I do with a QR code? Well, i could embed a link containing malicious content. Of course, I would mask the domain name using bit.ly or similar service. Most people these days don't think twice before clicking on bit.ly or other URL shortening services especially on twitter. It would be an interesting albeit illegal? experiment to see if people do really scan QR codes these days.