Technology

Insecurity Plagues Amber Alert System


A national alert system that gives the president the ability to take over

the U.S. airwaves during a national crisis may inadvertently extend hackers

the same courtesy, thanks to security holes that put radio stations,

television broadcasters and cable TV companies at risk of being commandeered

by anyone with a little technical know-how and some off-the-shelf electronic

components.

At issue is the Emergency Alert System (EAS), a nationwide network launched

in 1997 to replace the cold-war era Emergency Broadcast System known best

for making the phrase "this is only a test" a cultural touchstone. Like that

earlier system, the EAS is designed to allow the President to interrupt

television and radio programming and speak directly to the American people

in the event of an impending nuclear war, or a similarly extreme national

emergency. The EAS has never been activated for that purpose -- it was not

used on September 11th -- but state and local officials have found it a

valuable channel for warning the public of regional emergencies, recently

including the "Amber Alerts" credited with the recovery of several abducted

children over the summer.

But even with Amber's successes, the EAS is increasingly under fire by

critics who charge that its national mission is obsolete in an era of

instant 24-hour news coverage, and that the technology underlying it is

deeply flawed. One of the most stinging criticisms: that the EAS is wildly

vulnerable to spoofing, potentially allowing a malefactor to launch their

own message that in some scenarios could quickly spread from broadcaster to

broadcaster like a virus.

The system works this way: The Federal Emergency Management Agency (FEMA)

activates the EAS for a national alert through 34 radio stations around the

country that act as "primary entry points" (PEPs) for the system. Those

stations, typically all-news AM stations with powerful transmitters,

immediately interrupt their programming to broadcast the alert on the air.

The alert begins with a burst of data coded by a low-speed modem, repeated

three times. It's followed by an eight-second alert tone, and then spoken

emergency information and instructions -- or a presidential address --

before another burst of data terminates the message.

'NO SECURITY'. The data header is the key to the system -- it's what allows the same broadcast to simultaneously warn the public, and other broadcasters. To radio listeners, it sounds vaguely like

the quacking of a duck, but encoded within it is a timestamp, a station

identifier, a region code, an expiration time, and a three-letter event

code identifying the type of alert.

EAS boxes at hundreds of radio and TV stations are tuned in to at least one

of the PEPs, and to them the burst is a wake-up call. The equipment reads

the header, determines what kind of alert is being sounded, and then the

station interrupts its programming to retransmit it (with its own

identifier) on the air, and starts carrying the audio live.

Thousands of other stations are tuned to those broadcasters, and they do

the same, until the message has filtered all the way down the hierarchy,

even reaching cable T.V. companies which are required to interrupt every

channel for a national alert.

The problem, experts say, is that the EAS data headers include no

authentication protocol whatsoever. That means anyone capable of following

the specifications and with the skill to build a low-power radio transmitter

akin to a "Mr. Microphone" toy can get their own messages into the system --

commandeering a radio or television station with a custom broadcast of their

own, which would in turn be picked up by a cascade of other stations. An

attacker could even omit the end-of-message indicator, leaving some stations

off the air until engineers figure out the snafu.

"It's very, very simple to generate those messages, and there's literally

no security," says Richard Burgan, a Columbus, Ohio radio engineer who's

studied the problem. "If you were to go to one of the stations... and get

near their antenna and generate a false transmission, you could start an EAS

message that would lock up all the stations down the line.... You wouldn't

be able to get the whole state that way, but if you were to do a little

research you could pick the right point to get the most."

ALTERNATIVE PLANS PROPOSED. So-called "replay attacks," in which a spoofer records and retransmits a genuine message, would likely be thwarted by the region code and expiration time in the header. But the only thing preventing someone from generating their own original message are the system's non-standard 500 baud modems.

That's not much protection: the modem specs are published in the FCC

regulations, and the technology is simple and slow enough to be easily

emulated by any off-the-shelf PC with a sound card. A transmit-only modem

could even be built from scratch with a few dollars in components, according

to Burgan.

"The only thing that's mentioned in any document I have relating to security

is that you have to transmit the message clearly three times," says Burgan.

"And that's not security. I think they overlooked it entirely because it's

too complicated to do." The FCC adapted the EAS from an older National

Weather Service system used to issue severe weather warnings.

Large broadcasters have personnel assigned to handle EAS alerts manually,

and the humans in the loop provide a common-sense bulwark against obviously

false alerts. But many smaller stations and automated broadcasters turn

their transmitters over to the EAS automatically upon receiving an alert. A

false alert could trigger widespread panic, and undermine public confidence

in genuine warnings.

Though it's not known to have ever been exploited, the spoofing risk is one

of the factors quietly driving calls to reform the EAS. In a paper published

earlier this year, Columbia University researchers Henning Schulzrinne and

Knarig Arabshian proposed enhancing the system with an Internet-based

emergency notification system, noting that under the current design "it

would not be hard to drive by an EAS receiver with a small transmitter and

make it distribute a false alarm."

Peter Ward, chairman of the Partnership for Public Warning, a nonprofit group formed this year to explore advanced warning systems, would phase out the EAS, and replace it with an all-digital network tied to cell phones, digital

televisions and pagers, turning any networkable device into a "smart

receiver that would know the wishes of the owner, and could provide them

with the information they want to receive." He says the potential for

spoofing is only one the EAS's problems, and one that's "not likely to be

corrected soon."

FCC SILENCE. In fact, with weak security etched into FCC standards, the system effectively creates open backdoors into broadcast stations across the

country that the broadcasters are forbidden by law to secure. Burgan says

the government should shoehorn security into the existing system, possibly

by digitally signing EAS headers. "It wouldn't have to be very complicated

to make it highly secure," he says. So why didn't the FCC build in security

in the first place? "It's a classic case of something that was designed by

committee," he says.

Other experts say that's unfair. "I really think that the EAS has provided a

great service, and it needed to be simple to go into these mom and pop radio

stations, literally running their own business with a transmitter in the

back field," says Mark Manuelia, engineering manager at WBZ Radio in Boston,

one of the primary entry points for the system. "These things stand alone

in little radio station that have no Internet access... That's something we

don't think of where we are in big cities."

Manuelia says the FCC isn't to blame, because information security wasn't

on anyone's mind when the they were working on the plan in 1995. "They were

doing something that was better than was there before," he says. "Whether

they were thinking ahead to the year 2002 -- I guess they weren't."

The FCC is mum on the question -- indeed, on the entire issue. John Winston,

assistant chief of the enforcement bureau overseeing the system, says the

commission doesn't comment on EAS security. They're more talkative on

the system's popular new role in Amber Alerts, through which parts of the

country not prone to tornados and floods are becoming acquainted with EAS

for the first time.

Under Amber, in the minutes or hours immediately following a child

abduction, state officials use EAS to broadcast critical information like a

description of a suspect's vehicle to the public. (Highway signs also

disseminate Amber Alerts, and are not a part of EAS). The programs are

gaining in popularity: last week, New York became the 17th state to adopt a

statewide Amber Alert plan, and Senators Kay Bailey Hutchison and Dianne

Feinstein introduced a bill that would set up a nationwide Amber program.

Ward says the successful Amber programs demonstrate that the killer app for

warning systems is local alerting, not the national duck-and-cover message

that the EAS, and the Emergency Broadcast System it replaced, was built for.

"In the cold war days when we were talking about missiles coming over the

poles there was a much stronger fear that all the broadcast authorities

might have disappeared, and we needed a way for the President to commandeer

the surviving broadcasters." By Kevin Poulsen


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