Image: Cebraloko, Wikimedia Commons

Researchers from North Carolina State University have developed a new tool to detect and contain malware that attempts root exploits in Android devices. The tool improves on previous techniques by targeting code written in the C programming language – which is often used to create root exploit malware, whereas the bulk of Android applications are written in Java.

Xiaohui Gu

Root exploits take over the system administration functions of an operating system, such as Android. A successful Android root exploit effectively gives hackers unfettered control of a user’s smartphone.

The new security tool is called Practical Root Exploit Containment (PREC) and was developed by NC State computer science researcher Xiaohui Gu’s research team. It refines an existing technique called anomaly detection, which compares the behavior of a downloaded smartphone application (or app), such as Angry Birds, with a database of how the application should be expected to behave.

When deviations from normal behavior are detected, PREC analyzes them to determine if they are malware or harmless “false positives.” If PREC determines that an app is attempting root exploit, it effectively contains the malicious code and prevents it from being executed.

“Anomaly detection isn’t new, and it has a problematic history of reporting a lot of false positives,” says Will Enck, an assistant professor of computer science at NC State and co-author of a paper on the work. “What sets our approach apart is that we are focusing solely on C code, which is what most – if not all – Android root exploits are written in.”

“Taking this approach has significantly driven down the number of false positives,” says Gu, an associate professor of computer science at NC State and co-author of the paper. “This reduces disturbances for users and makes anomaly detection more practical.”

The researchers are hoping to work with app vendors, such as Google Play, to establish a database of normal app behavior.

Most app vendors screen their products for malware, but malware programmers have developed techniques for avoiding detection – hiding the malware until users have downloaded the app and run it on their smartphones.

The NC State research team wants to take advantage of established vendor screening efforts to create a database of each app’s normal behavior. This could be done by having vendors incorporate PREC software into their app assessment processes. The software would take the app behavior data and create an external database, but would not otherwise affect the screening process.

“We have already implemented the PREC system and tested it on real Android devices,” Gu says. “We are now looking for industry partners to deploy PREC, so that we can protect Android users from root exploits.”

The paper, “PREC: Practical Root Exploit Containment for Android Devices,” was presented at the Fourth ACM Conference on Data and Application Security and Privacy. Lead author of the paper is former NC State graduate student Tsung-Hsuan Ho. The paper was co-authored by Daniel Dean, a Ph.D. student in Gu’s lab at NC State.

The work was supported with funding from the National Security Agency, the U.S. Army Research Office, the National Science Foundation, IBM Faculty Awards, and Google Research Awards.