The United States Emergency Alert System (EAS) in 1997 replaced the older and better known Emergency Broadcast System (EBS) used to deliver local or national emergency information.
The EAS is designed to “enable the President of the United States to speak to the United States within 10 minutes” after a disaster occurs. In the past these alerts were passed from station to station using the Associated Press (AP) or United Press International (UPI) “wire services”, which connected to television and radio stations around the U.S. Whenever the station received an authenticated Emergency Action Notification (EAN), the station would disrupt its currentbroadcast to deliver the message to the public.
DASDEC is one of a small number of application servers that now fill the role of delivering emergency messages to television and radio stations. DASDEC encoder/decoders receive and authenticate EAS messages delivered over National Oceanic and Atmospheric Administration (NOAA) radio or relayed by a Common Alerting Protocol (CAP) messaging peer.
After a station authenticates an EAS message, the DASDEC server interrupts the regular broadcast and relays the message onto the broadcast preceded and followed by alert tones that include some information about the event.
An attacker who gains control of one or more DASDEC systems can disrupt these stations’ ability to transmit and could disseminate false emergency information over a large geographic area. In addition, depending on the configuration of this and other devices, these messages could be forwarded to and mirrored by other DASDEC systems.