Shellshock attackers targeting NAS devices

Researchers have discovered hackers trying to exploit the Shellshock Bash vulnerability to compromise network attached storage devices in universities in the U.S., Japan and Korea.

The attackers were taking advantage of a publicly disclosed security weakness in which the web servers embedded in the devices manufactured by QNAP have administrative privileges by default, researchers for FireEye said Wednesday.

Once attackers compromise the server and get these privileges, they have full control of the device.

“They (QNAP) acknowledged this particular vulnerability on their website,” Josh Gomez, security researcher at FireEye, said.

Knowing the vulnerability existed; the attackers scanned the devices for Shellshock and downloaded malware using autostart script provided by the manufacturer, James Bennett, threat researcher for FireEye, said. The script is used to have programs start automatically.

“The attackers did some research on these devices,” Bennett said.

All QNAP devices run an embedded Linux operating sytems that is vulnerable to CVE-2014-6271, one of six flaws in GNU Bash, which stands for Bourne Again SHell. Collectively, the vulnerabilities have been dubbed Shellshock.

The attacks are the first FireEye has seen targeting NAS devices, which would be desirable targets, because of the amount of data stored in them.

“There’s a lot of data on these devices that could be sensitive, interesting or valuable,” Bennett said.

FireEye, which monitors enterprise networks for malware, discovered attacks against about 20 QNAP devices. Most were located in Japan with a few in Korea and a couple in the U.S. All the attacks were against research universities.

The QNAP attacks followed a typical pattern for exploiting Shellshock. The vulnerabilities in Bash, which is the default command shell for Linux, will execute malicious command code sent vie the Common Gateway Interface. CGI is the underpinning of the management console in the QNAP Web server.

Security experts have provided half a dozen steps organizations can take to prevent Bash exploitations, including installing the latest vendor-provided patches, monitoring system logs and asking manufacturers whether their devices are vulnerable. Device that cannot be patched should be replaced.

In other related news, Mullvad, a Swedish virtual private network provider, reported Tuesday that OpenVPN servers are vulnerable to Shellshock, under certain configurations.

Akamai Technologies, an Internet content delivery network, reported seeing a total of 22,487 unique attacking IP addresses, with 156 being HTTP proxies. Almost 70 percent of the addresses originated from the U.S.

The top domain under attack was online gaming with consumer electronics and online email marketing a distant second and third, respectively.