SNMP Scan Nets Thousands of Vulnerable Devices

If your network management people and your security people still aren’t talking, here’s another reason they should: researchers with the GNUCitizen hacker group have discovered details on over 5,000 SNMP-enabled devices on the Internet just by sending out random SNMP queries.

In a recent scan experiment, the researchers found names, models, and even patching information on some of these devices, which included brand-name routers such as Cisco, printers, VOIP phones and modems, and servers running Windows, FreeBSD, and Linux.

“It's worth noting that such systems' returns [included] very specific information such as full patching level of OS,” says Adrian Pastor, a researcher with GNUCitizen who has recently been conducting a range of SNMP vulnerability research, including a proof-of-concept for an attack that uses SNMP to launch a cross-site scripting attack. (See SNMP Joins Dark Side in New XSS Attack and Phishing for SNMP.)

Among the products that responded the most to GNUCitizen’s SNMP requests were ARRIS Touchstone Telephony modems, which accounted for over 35 percent of the devices they detected; various models of Cisco routers; Apple AirPort and Base Station wireless products; ZyXEL Prestige routers; Netopia routers; and Windows 2000 servers.

Pastor says that SNMP security issues aren’t new, but there are still plenty of SNMP-enabled devices exposed on the Internet. All it takes is SNMP read access to get their brand and model and other sensitive information for potential hacking purposes.

“There are still many Internet-visible systems waiting to be compromised via SNMP... many devices run SNMP by default, which is bad news,” Pastor says. “Another thing that I learned is that many systems that are firewalled are protected from TCP probes, but not UDP [which SNMP is based on]. In other words, you might find a bunch of hosts that cannot be probed via TCP services but still allow for a potential compromise via SNMP.”

Researcher HD Moore points out that there are lots of SNMP-scanning and brute-force hacking tools available today. “It’s fun research and I’m glad they shared the results, but it’s definitely not groundbreaking,” says Moore, director of security research at BreakingPoint Systems and creator of Metasploit, which also supports SNMP hacking.

“A counterpoint is that the only reason so many of these devices are exposed in the first place is because nobody manages them, via the Web interface or otherwise,” Moore says.

GNUCitizen researchers queried 2.5 million random IP addresses, but only about 5,320 of them responded to the SNMP requests. Pastor says several factors contributed to the low turnout, including the fact that SNMP is mostly enabled on embedded devices, which represent a relatively small piece of the Net, and because some of the IP addresses the researchers queried could have been internal IP addresses or are unassigned.

Some ISPs ship Internet routers, such as ZyXEL’s Prestige, with custom configurations that leave SNMP wide open to the Net, Pastor says. Other vulnerable devices’ SNMP woes could be due to factory default settings, for instance, he adds.

“SNMP read access could [be] enough to fully own a device!” he wrote in a GNUCitizen blog post today.

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