The Dallas City Council voted to spend up to $100,000 to add security upgrades to the emergency siren system that was hacked late Friday night.

Little was said about the emergency action item because of security concerns. But downtown council member Philip Kingston said shortly before the vote on Wednesday that the deal with Michigan-based West Shore Services is "something I have confidence will ensure the siren system is secure in the future."

The council was briefed behind closed doors about the signal spoof and the city's contract with West Shore, which, last November, was awarded a $567,368, six-year contract to maintain and repair all 156 of the city's emergency sirens. Company executives were on the phone with city officials at 2 a.m. Saturday morning trying to figure out what had gone wrong.

Initially, the city said the sirens, which are radio-controlled via encoded transmitters that send tones, had fired off because of a malfunction. But by Saturday afternoon it had become clear: The system was hacked by someone who had managed to replicate the signal that triggers the system.

City spokeswoman Sana Syed said Wednesday that no one has stepped forward to take responsibility for the hack. Rocky Vaz, Dallas' director of emergency operations, said over the weekend that officials believe the sirens were activated locally -- likely because they are radio-activated, with receivers attached to each of the sirens.

One security consultant said earlier his week that it's possible the hack was the result of an inside job committed by someone who knows the tones needed to turn the sirens on and off and has the equipment to pull off such a job. But others, among them former government officials, told The Dallas Morning News on Wednesday that might not be the case.

After all, said Brandon McCrillis, principal information security consultant for Rendition InfoSec, these sirens rely on "old technology" that is "pretty archaic."

McCrillis said anyone who can hack a computer can certainly crack a system relying on radio transmissions.

"You're modulating using two tones -- ones and zeroes," he said. "It's similar to how bits on the wire are transmitted. If you're good at computer hacking, you would have an aptitude for looking at things in the binary sense."

Fact is, said James Norton, founder and president of cybersecurity firm Play-Action Strategies, municipal governments' security systems are popular and easy targets -- because cities often don't have the money to pay for the latest and greatest in security upgrades. They also don't think they're vulnerable to attack, as evidenced by Dallas' hack: City officials told The Dallas Morning News earlier this week that the siren system was never encrypted simply because the city and the manufacturer, Illinois-based Federal Signal Corp., to whom the city paid upwards of $3 million for an upgrade beginning in 2007, didn't think it could happen here.

"It's probably not a one-and-done," said Norton, who was a deputy assistant secretary of the U.S. Department of Homeland Security under President George W. Bush. "I think you will see more of it as it goes on, as organizations look to target major cities and find gaps. It could have been some folks wanting to send a signal ... or a lead-up to something else. It's hard to speculate.

"But it's a warning to the state and locals to update their systems and become more sophisticated."

Dallas City Manager T.C. Broadnax said Monday that the siren system was encrypted within 48 hours of the hack, and that other security measures had been taken. He also said the city was going to bring in an outside consultant to review all of its vulnerabilities, from the 911 call center to Dallas Water Utilities.

Mayor Mike Rawlings said Saturday that the siren hack proves there is a "need for us to upgrade and better safeguard our city's technology infrastructure ... a costly proposition."

The $100,000 approved by the council Wednesday is but the beginning of that spend.