Friday, 9 September 2016

On 23:18 by admin   No comments
Critical to the success of the 911 emergency phone system, which has saved countless lives since it was first implemented in 1968, is its ability to quickly route calls to emergency responders closest to a caller.
But a group of researchers say they’ve found a way to effectively disable the 911 emergency system across an entire state for an extended period of time by simply launching what’s known as a TDoS attack, or telephony denial-of-service attack, against 911 call centers. The tactic involves infecting mobile phones to cause them to automatically make bogus 911 calls — without their owners' knowledge — thereby clogging call-center queues and preventing legitimate callers from reaching operators.
The researchers say it would take just 6,000 infected smartphones in a geographical area — something hackers could easily accomplish — to launch an attack sufficient to disrupt the 911 system throughout the entire state of North Carolina, and just 200,000 infected phones distributed across the U.S. to significantly disrupt 911 services around the nation. 
“Under these circumstances, an attacker can cause 33 percent of the nation's legitimate callers to give up in reaching 911,” the researchers at Ben Gurion University in Israel wrote in a paper they recently passed to the Department of Homeland Security and are releasing publicly today. 
Because call centers and routers around the country often operate at near capacity under normal conditions, increasing the volume of calls by just a small percentage can overwhelm them, said Mordechai Guri, head of R&D at the university's Cyber Security Center and chief scientist at Morphisec Endpoint Security. Guri conducted the work with researcher Yisroel Mirsky and Professor Yuval Elovici, head of the center.
"We believe the researchers have accurately characterized the problem" with the 911 system, said Trey Forgety, director of government affairs for the National Emergency Number Association, who received a copy of the researchers' paper from DHS. He says his group has long been aware of the potential for a TDoS attack and brought it to the attention of DHS four years ago. "We actually believe that the vulnerability is in fact worse than [the researchers] have calculated."
The call capacity of 911 systems is exceptionally limited, and in many cases just three to five circuits process all 911 calls for a 911 center, Forgety said. "Three to five circuits is trivial to overwhelm. I can do it with a pocketful of cellphones."
The federal government considers the 911 system to be part of the nation's critical infrastructure on par with the power grid, water treatment plants and dams. Americans make more than 240 million calls annually to more than 7,000 call centers scattered across the country. About 70 percent of these calls now come from mobile phones. But the technology used to process these calls hasn't kept pace with security needs, experts say.
An attack could be prolonged for days using techniques that would prevent authorities from halting the bogus calls, Guri and his colleagues say. The problem would be exacerbated as legitimate callers trying to get through made repeated calls that further clogged the lines.
Denial-of-service attacks against 911 systems have been discussed as a concept at hacker conferences for years, although it's not known if any 911 outage has ever been caused by a TDoS attack. But in 2013, something occurred that indicated that attackers have 911 call centers in their sights. DHS and the FBI issued a warning to states about several TDoS attacks that had been launched against the administrative lines of various 911 call centers. Although these attacks didn’t target the 911 emergency lines themselves, they demonstrated the potential danger from TDoS attacks against the 911 system. The perpetrators launched the attacks as part of an extortion plot — after first demanding money and being turned down, they “launched high volume of calls against the target network, tying up the system from receiving legitimate calls,” according to the DHS alert.


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