UW Computer Security Research and Course Blog

Authors: Heather Underwood & Guy Bordelon

As mobile phones continue to become one of the most popular, universal, and comprehensive computing devices, researchers and mobile phone companies are enthralled with adding more features. As described in a recent article by the New Scientist, the feasibility of including a projector on a mobile phone is becoming a reality. The new projector chip that TI released a few weeks ago dramatically improves upon last year’s low resolution model by adding more mirrors to increase the resolution to 850 by 480 pixels (comparable to a DVD player). This new model also works better in most lighting conditions and can show a 2 hour movie on a single battery charge. Having mobile phone projectors provides many exciting opportunities, but also creates some interesting security challenges. Some of these challenges are not critical security issues, but could cause frustrating or embarrassing situations.

Assets/Security Goals:

• The mobile phone projector would provide easier sharing of presentations, photos, videos, etc.
• Low power consumption would allow for mobile presentations and viewing without having to recharge batteries or be near a power outlet.
• The dual display will allow users to view private information on the little screen on their phone while displaying public information on the projection screen. This security measure will enhance presentations by allowing the user to view notes or comments while displaying slides or have other sorts of private captioning for private viewing while different content is being projected.

Adversaries/Threats:

• An adversary of the mobile phone projector could use the projector and other phone functionality like video to project real-time activity to a group. For instance, voyeurs could capture content from a distance using zoom camera/video features and project the inappropriate content in real time. The content could also be recorded and then displayed at a later time to blackmail or embarrass the victim.
• Another possible threat is theft. If a phone is stolen and the projector has been projecting the same image, say a bank statement, for a very long time or is very often projecting that image, a clever thief could gain information from the image impression on the lens. This would most likely occur on older projector phones where the lens is sufficiently worn.

Weaknesses:

• One possible weakness is that personal and private information could be maliciously projected without the phone owner’s permission. If appropriate checks are not in place, the owner could also accidently display his private information in an inappropriate setting.
• The projector also opens up a new way for people to be incredibly obnoxious. The weakness here is not ensuring the security of people’s privacy and their sanity in public places. Projections of videos and photos in a restaurant or movie theater would be incredibly rude and distracting.
• Another weakness is there is no limitation on the content the projector projects or the context in which it is projected. This weakness may not be readily solved by implementing greater security measures, but could end up relying on a social protocol that may or may not keep discriminating, hateful, or indecent material from being projected everywhere.

Potential defenses:

• One potential defense is to have a password to use the projector so only the owner can access and project the content on their phone. This security measure does not protect against the owner knowingly projecting indecent or private information however.
• The projector should also require a confirmation screen before projecting the selected content. This security measure would hopefully eliminate accidental display of private or indecent information on the projector.
• A solution for reducing the use of the projector in public places, besides signs and glaring looks from other customers, could be sensors (on the phone and at the restaurant) that could detect and essentially disable projection of phone content.

Evaluation:

The main goal of this device is to make accessing and viewing content easier and more available for entertainment and larger scale purposes. The projector was not designed to provide added security to mobile phones and thus there are few security goals, however, because security was not a main concern when developing this device, there are multiple security flaws that were not taken into account. We think this technology will very likely become a standard feature of mobile phones. Teenagers especially will drool over being able to project their Facebook pictures and YouTube videos larger than life in any place they want. We also think that tech-savvy business people will utilize this tool for portable presentations. This device also has many applications in the developing world where power consumption, carrying heavy video equipment and easily watching educational videos is often a problem. There are obviously ethical questions involved with this device in regards to what content is appropriate to project, however, there are many devices that have advanced technology and failed to account for all possible ethical misuses.
Although there may be some technological solutions to the security vulnerabilities presented above, we think if the projector becomes a popular and ubiquitous feature of cell phones, the use of it will ultimately be governed by a social protocol and people being conscious of the content they are showing. The article suggests that requiring additional legislation for projected content could become necessary, but we are of the opinion that requiring legislation to prevent people from being stupid has never and will never work.