More than 4 million consumer and business devices—such as routers, media servers and Web cams—could be conscripted by attackers to participate in a distributed denial-of-service attack because of weaknesses in the Universal Plug-and-Play (UPnP) standard, Internet infrastructure firm Akamai warned in an advisory posted on Oct. 15.
Attackers have exploited the protocol to send control messages to UPnP devices, discovering a way to trigger a response from the devices that can be directed to inundate a targeted network, Akamai stated in its advisory.
DDoS attacks using the approach have been steadily increasing since July, when Akamai first detected the technique and now account for 7.3 percent of infrastructure attacks, Rod Soto, principal security researcher with Akamai’s Prolexic Security Engineering and Research Team (PLXsert), told eWEEK.
"It is a huge number for a new denial-of-service vector," he said.
Reflection and amplification attacks use unauthenticated communications within the Internet infrastructure to distribute the apparent sources of an attack and magnify the volume of data sent to a target. Reflection attacks send forged network requests to vulnerable devices—Domain Name Service (DNS) and Network Time Protocol (NTP) servers are common—which then respond to the spoofed source address. The attacks appear to come from a large number of devices, rather than the few systems controlling the attack. Amplification attacks work similarly, but are focused on protocols that have large responses compared to the request size. NTP servers, for example, can be manipulated into magnifying a 64-byte request by a factor of more than 700.
In the UPnP attack, malicious operators use the Simple Service Discovery Protocol (SSDP) and send spoofed control packets. The attack is useful for both reflection attacks, given the number of vulnerable devices, and amplification as researchers estimate that it can magnify attack traffic by a factor of 30, according to Web security firm Sucuri.
By using thousands, or tens of thousands, of devices, attackers can inundate a network with data, Akamai's Soto said. In a recent attack, Akamai witnessed a combined bandwidth of 54 Gbps, which falls short of the massive 300 Gbps used in an amplification attack against antispam group SpamHaus, but is still much larger than typical attacks.
"When you put it together and you add a lot of these types of devices, you will get a sizable bandwidth," he said.
Akamai has found two tools—ssdpscanner.py for scanning and ssdpattack.py for the actual attack—that have been used to conduct UPnP reflection campaigns.
A scan of the Internet found 11 million vulnerable UPnP devices, but only 38 percent of those devices, about 4.1 million, appear to respond to spoofed commands, Akamai stated in its analysis. South Korea has the largest number of vulnerable devices, followed by the United States, Canada, and China.
"The prevalence of vulnerable devices is likely to drive the development of new tools to take advantage of the SSDP and SOAP protocols, which will likely also lead to UPnP device-based reflection attack tools and botnets being monetized in the DDoS-for-hire underground market," the company warned.