Unplug Universal Plug And Play: Security Warning

More than 23 million Internet-connected devices are vulnerable to being exploited by a single UDP packet, while tens of millions more are at risk of being remotely exploited.

That warning was issued Tuesday by vulnerability management and penetration testing firm Rapid7, which said its researchers spent six months studying how many universal plug and play (UPnP) devices are connected to the Internet -- and what the resulting security implications might be. The full findings have been documented in a 29-page report, "Security Flaws In Universal Plug and Play."

"The results were shocking, to the say the least," according to a blog post from report author HD Moore, chief security officer of Rapid7 and the creator of the open source penetration testing toolkit Metasploit. "Over 80 million unique IPs were identified that responded to UPnP discovery requests from the Internet."

UPnP is a set of standardized protocols and procedures that are designed to make network-connected and wireless devices easy to use. Devices that use the protocol -- which is aimed more at residential users rather than enterprises -- include everything from routers and printers to network-attached storage devices and smart TVs.

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Despite its convenience, approximately 45 million of the UPnP-using IP addresses spotted by Rapid7 led to a device that's vulnerable to one of three attacks, which are outlined in the company's report. "All told, we were able to identify over 6,900 product versions that were vulnerable through UPnP. This list encompasses over 1,500 vendors and only took into account devices that exposed the UPnP SOAP service to the Internet, a serious vulnerability in of itself," Moore said.

"We strongly suggest that end users, companies and ISPs take immediate action to identify and disable any Internet-exposed UPnP endpoints in their environments," said Moore. "UPnP is pervasive -- it is enabled by default on many home gateways, nearly all network printers and devices ranging from IP cameras to network storage servers."

To help people spot vulnerable UPnP devices, Rapid7 released ScanNow for Universal Plug and Play. The free scanner for Windows can be used to "identify exposed UPnP endpoints in your network and flag which of those may [be] remotely exploitable through recently discovered vulnerabilities," said Moore. The exploitable vulnerabilities have already been added to the Metasploit open source penetration testing framework.

One of the most likely targets of a UPnP attack would be routers, since attackers could alter the DNS settings to point the device to an attacker-controlled server. At that point, the attacker could use the router to send spam, run a clickjacking scam to profit from false advertising impressions, or even eavesdrop on all traffic being sent through the device.

Interestingly, Moore found that 73% of all discovered Internet-facing UPnP instances were built with one of just four software development kits, and versions of two of those kits -- MiniUPnPd and Portable SDK for UPnP -- contain remotely exploitable vulnerabilities. "In the case of the Portable SDK for UPnP, over 23 million IPs are vulnerable to remote code execution through a single UDP packet," he said.

Some of the exploitable flaws have already been patched in the software development toolkits, such as Portable UPnP SDK version 1.6.18, which was released this week. But even with the SDK fixes, don't expect patches to be released for most of the vulnerable devices. "It will take a long time before each of the application and device vendors incorporate this patch into their products," said Moore. "In most cases, network equipment that is 'no longer shipping' will not be updated at all, exposing these users to remote compromise until UPnP is disabled or the product is swapped for something new."

Indeed, the exploitable flaws spotted in the MiniUPnP SDK were excised from the software more than two years ago. "Yet over 330 products are still using older versions," said Moore.

This isn't the first security warning involving UPnP devices. For example, US-CERT issued a security alert in 2008 after finding that the devices could be exploited via a malicious Flash file, which could be used to infect a victim's system and then take control over any connected device that supports UPnP. In 2001, meanwhile, researchers at eEye warned that vulnerabilities in Microsoft's implementation of UPnP -- later patched -- could be exploited to trigger a buffer overflow and give an attacker access to any default installation of Windows XP.