Latest Android Malware Infects Gingerbread via Jailbreak Exploit

The latest malware targeting Android devices takes advantage of a jailbreak exploit to gain root-level access and executes instructions from a remote server.

Researchers have uncovered the first malware using the "Gingerbreak" root exploit for Android 2.3, code-named "Gingerbread."

GingerMaster, a variant of the DroidKungFu malware that appeared earlier this year, has a root exploit that gives the attacker control of the infected device, Xuxian Jiang, an associate professor at North Carolina State University's department of computer science, wrote in a blog post Aug. 18. NC State researchers worked with mobile security vendor NetQin and discovered that GingerMaster wrapped malicious code around a jailbreak exploit for Android 2.3 devices.

Once the malicious application is downloaded and installed onto the device, it gains root privileges on the computer and transmits data stored on the device to a remote server, the researchers said. The information stolen includes the user identifier, SIM card number, telephone number, IMEI number, IMSI number screen resolution and local time, according to Vanja Svajcer, a principal virus researcher in SophosLabs.

"The GingerMaster malware is repackaged into legitimate apps," said Jiang. The applications masquerade as popular applications to encourage users to download it. The researchers also found that several mobile antivirus tools failed to detect the applications as malicious.

Svajcer analyzed the application, which claims to display "Beauty of the Day" pictures. Available from a Chinese alternative Android Market, the application requested 16 different permissions from the user upon installation, including the ones to read logs, access the Internet, write to the SD card, access the file system and access owner data.

Once installed, GingerMaster will also attempt to install a root shell into the system partition for later use. The malware also installs various utilities onto the partition, "supposedly to make removal more difficult" and for additional functionality, Svajcer said. Once a malicious process gets roots, "its powers are potentially unlimited," he said.

With control over the mobile device, GingerMaster contacts the remote command-and-control server for follow-up instructions. It can download and install applications on its own without the user's permission, Jiang found.

It's "exceptionally difficult" to gauge the impact of Android malware distributed outside the official Android market, Tim Armstrong, a malware researcher at Kaspersky Lab, told eWEEK. "Due to the fact that new variants keep arriving, we can assume there is money being made, and users being infected, or the malware authors would likely move onto other platforms," Armstrong said.

Users should avoid alternative Android Marketplaces unless they have "strong evidence" the applications are trustworthy, Svajcer recommended. Kaspersky's Armstrong pointed out that the term "alternative markets" also includes independent Websites, forums, peer-to-peer sharing sites and even email, as users can install applications from all these sources.

More importantly, users should look at the permissions list and avoid installing applications that request more than what seems reasonably necessary. GingerMaster is an application that downloads pictures from a Website, Svajcer said, adding, "Why would it need permissions such as WRITE_USER_DATA and MOUNT_UNMOUNT_FILESYSTEMS?"

Android malware attacks have jumped by 76 percent over the past three months, making Android the most heavily attacked mobile platform, McAfee found in its latest quarterly threat report, released Aug. 22.

"The Android malware writing scene is heating up as the season of summer holidays is coming to its end. Last week, we received a record number of samples which are now waiting to be analyzed in detail," said Svajcer.

GingerMaster may compromise Android 2.2 and earlier devices with some adjustments, Jiang said. Even though Google has updated Gingerbread several times since it was released in December, many carriers have not yet updated their devices to the latest version of 2.3.3 or to 2.3.4. Jiang's team also found other DroidKungFu variants in alternate Android application stores that used similar root exploits for earlier versions of Android.