The researchers analyzed popular tracker apps available in the Google Play Store. Tthe result: not even one of them was secure; all had serious security flaws. Attackers can exploit these vulnerabilities to generate movement profiles, to read chats and text messages, and to view pictures. A particularly precarious fact: attackers do not have to monitor each individual phone but can simultaneously attack millions of users, who have these apps installed on their smartphones. The researchers presented their results for the first time at the DEF CON Hacking Conference in Las Vegas on August 11.
Monitoring or tracker apps allow the consensual surveillance of smartphone users. For example, parents use such an app to monitor where their children are or which messages and pictures they post online. Using these apps is legal as long as the person under surveillance has agreed to it. Fraunhofer SIT scientists from the ethical hacking group TeamSIK have analyzed 19 legal tracker apps offered in the Google Play Store. According to Google, these apps have been installed several million times over. The scientists reviewed how the apps protect the highly sensitive user data they gather. The result: All apps showed severe vulnerabilities, not a single application was programmed with default security features in place. The researchers found 37 vulnerabilities in total.
Most apps store the highly sensitive data on a server in plain text, without any proper form of encryption. "We only had to open up a certain website and guess or enter a user name into the URL to retrieve an individual's movement profile," explains Fraunhofer head of project Siegfried Rasthofer. The vulnerabilities not only affected individual users. Instead, the researchers were able to read out complete movement profiles for all app users, all of which were stored unprotected on that server. "With this, thousands of people can be tracked in real-time," says Rasthofer. These apps allow attackers to retrieve metadata such as a person's whereabouts, and to read or view contents including SMS messages and images of the monitored app users. "It enables total surveillance," explains Stephan Huber, Fraunhofer SIT researcher and member of TeamSIK.
The scientists also succeeded in reading the app users' login information. Mostly, the apps used improper encryption or no encryption at all. In the backend of one app alone, the research team found 1.7 million valid login credentials that were freely accessible. The Fraunhofer researchers informed the app providers and Google Play Store team. Meanwhile, the Google Play Store team has deleted 12 of the 19 analyzed apps from the store. Notably, some app developers did not react to the team's vulnerability reports.