'Skulls' Trojan Taking Out Cell Phones with Symbian OS

Symbian has reported that a virus dubbed "Skulls" has been introduced to its operating system for wireless phones. The malware is targeted at the Nokia 7610 smart phone, but might affect other phones using Symbian's Series 60 User Interface.

Skulls is a malicious SIS file trojan that will replace the system applications with non-functional versions in order to disable everything except the phone functionality, according to antivirus software maker F-Secure.

The file is named "Extended theme.SIS" and claims to be a theme manager for the Nokia 7610 smart phone, written by "Tee-222." The malware was located on some Symbian shareware download sites.

Poisoning Applications

"Skulls SIS file does not contain any malicious code as such, it is just a Symbian installation file that installs critical System ROM binaries into C: drive in with exact same names and locations as in the ROM drive," according to the F-Secure report.

"The malicious part is in the AIF (application info and icon) file which comes with the applications," the report said.

If Skulls is installed, it will replace all application icons with a picture of skull-and-crossbones, disallowing the launch of phone system applications like Web browsing, camera and text messaging. Users can still make and receive calls.

F-Secure warns users who get the virus not to reboot the phone. The security firm advises users to follow the disinfection steps on its Web site in order to delete the two faulty files.

Symbian Speaks

"It is Symbian's understanding that the suspected malware is no longer being distributed," company officials said in a statement. "It is unclear if the adverse effects of this software are the result of deliberate development (a trojan) or an inadvertent side-effect of poor software programming."

Users would have to deliberately install Skull as an application in order to be affected, according to company officials. The malware cannot be installed without repeated user intervention, including ignoring a security warning. And the malware does not appear to have the ability to distribute itself to other phones.

The company said it takes security issues very seriously and works closely with the security community to develop and integrate the most advanced security features for Symbian OS.

Threat To Watch

While mobile phone viruses are not all that commoon today, IDC wireless analyst David Linsalata told the E-Commerce Times that these kinds of attacks are something to keep a close eye on.

"People are starting to think about how they could write viruses for mobile devices," Linsalata said. "There is certainly the potential for abuse as these devices become more popular."

Unlike the personal computing world, the mobile device industry has yet to see an attack that has been particularly threatening or widespread. However, Linsalata said if someone can figure out a way to release a very successful virus, then the possibility of wider damage is real.

Viruses could possibly be written that would allow hackers to use someone else's phone to send text messages or retrieve private information in transit over a wireless network, according to analysts.

The good news, Linsalata said, is that mobile operating system manufacturers and antivirus software makers are aware of the potential problems and are taking steps to add more security to mobile devices.

"Companies are keeping a close eye on mobile device security," he said. "Viruses are not a serious concern right now, but there is an awareness of the potential problems."