Mask sprider sig via Linksys E-routrar

The worm, which has been dubbed TheMoon because it contains the logo of Lunar Industries, a fictitious company from the 2009 movie “The Moon,” begins by requesting a /HNAP1/ URL from devices behind the scanned IP addresses. HNAP—the Home Network Administration Protocol—was developed by Cisco and allows identification, configuration and management of networking devices.

The worm sends the HNAP request in order to identify the router’s model and firmware version. If it determines that a device is vulnerable, it sends another request to a particular CGI script that allows the execution of local commands on the device.

The worm works by injecting vulnerable devices with a URL-encoded shell script that carries out the same seek-and-hijack behavior. The exploit may also change some routers' domain name system server to 8.8.8.8 or 8.8.4.4, which are IP addresses used by Google's DNS service. Compromised routers remain infected until they are rebooted. Once the devices are restarted, they appear to return to their normal state. People who are wondering if their device is infected should check for heavy outbound scanning on port 80 and 8080, and inbound connection attempts to miscellaneous ports below 1024. To detect potentially vulnerable devices use the following command:

echo "GET /HNAP1/ HTTP/1.1\r\nHost: test\r\n\r\n" | nc routerip 8080
Devices that return the XML HNAP output may be vulnerable.