Last month I briefly mentioned the importance of full disk encryption. Namely it prevents the contents of the hard drive from being altered unless one knows the decryption key. I had to deal with a friend’s significant other installing spyware on her system in order to keep tabs on who she was talking to and what she was doing. Her significant other didn’t know her login credentials but since her hard drive wasn’t encrypted he was able to install the spyware with a boot disk. This threat model isn’t out of the ordinary. In fact it is becoming worryingly common:
Helplines and women’s refuge charities have reported a dramatic rise in the use of spyware apps to eavesdrop on the victims of domestic violence via their mobiles and other electronic devices, enabling abusers clandestinely to read texts, record calls and view or listen in on victims in real time without their knowledge.
The Independent has established that one device offering the ability to spy on phones is being sold by a major British high-street retailer via its website. The proliferation of software packages, many of which are openly marketed as tools for covertly tracking a “cheating wife or girlfriend” and cost less than £50, has prompted concern that police and the criminal justice system in Britain are failing to understand the extent of the problem and tackle offenders.
A survey by Women’s Aid, the domestic violence charity, found that 41 per cent of domestic violence victims it helped had been tracked or harassed using electronic devices. A second study this year by the Digital Trust, which helps victims of online stalking, found that more than 50 per cent of abusive partners used spyware or some other form of electronic surveillance to stalk their victims.
As a general rule security is assumed to be broken when an adversary has physical access. But that isn’t always the case. It really depends on how technically capable a threat is. Oftentimes in cases of domestic abuse the abuser is not technically savvy and relies on easy to procure and use tools to perform monitoring.
Full disk encryption, while not a magic bullet, is pretty effective at keeping less technically capable threats from altering a drive’s contents without the owner’s knowledge. When encrypting the contents of a hard drive is not possible, either due to technical limitations or the threat of physical violence, the Tails Linux live distribution is a good tool. Tails is being developed to maintain user anonymity and leave a few traces as possible that it was used. All Internet traffic on Tails is pumped through Tor, which prevents a threat monitoring your network from seeing what you’re looking at or who you’re talking to (but does not disguise the fact that you’re using Tor). That can enable a victim to communicate securely with an individual or group that can help. Since Tails boots from a USB stick or CD it can be easily removed and concealed.
As monitoring tools becomes easier to use, cheaper, and more readily available the need to learn computer security will become even greater. After all, the National Security Agency (NSA) isn’t the only threat your computer environment may be facing. Domestic abusers, corrupt (or “legitimate”) law enforcers, land lords, bosses, and any number of other people may with to spy on you for various reasons.