Hackers can bring a cellular network to a standstill by flooding it with SMSs equivalent to spam, say computer researchers in the United States.
Researchers at Pennsylvania State University released a report in September claiming that cellular networks in large cities could easily be taken down by hackers who send up to 165 SMSs per second into one particular network.
The research analysed the Global System for Mobile (GSM) communication, the type of network technology that Cell C, MTN and Vodacom all use.
The report states: “Because text messages and mobile phone-call set-ups rely on the same limited resource, namely control channels, it is possible to attack this system.
“If enough text messages are sent … no more control channels are available and calls will begin blocking (ie, will not be connected).”
The New York Times reported on the research document, which evaluated the “security impact of internet-originated text messages on cellular voice and SMS services in the United States”.
The New York Times article quoted Patrick McDaniel, a professor of computer science and engineering at Pennsylvania State University and the lead researcher of the report, as saying that by pushing 165 messages a second into a network, “you can congest all of Manhattan”.
However, Pieter de Villiers, CEO of Clickatell — a South African mobile messaging company based in Cape Town — disagrees with the US report and told the Mail & Guardian Online that it would cost a hacker nearly $4 000 (about R26 200) per minute to deliver 165 messages.
“There’s no hacker that I know of whose got $4 000 just to pull a prank. There’s only two ways to deliver 165 SMSs per second. One is if you have 165 phones and the other is if you have 165 connected modems,” he said.
Even if a hacker manages to pull off the prank and send out 165 SMSs per second, the messages would only congest the network for a “couple of seconds”.
He responded to the New York Times article in a letter by saying: “An alternative scenario is gathering together 165 people to send an SMS at once. This too is unlikely due to the complicated logistics as well as SMS’s store-and-forward capability.
“This means that if a message is not delivered, it will wait until the network or phone is available to be delivered at a later stage.”
De Villiers admitted to the M&G Online that it is possible to congest a cellular network by overloading it, but says it’s virtually impossible because most networks cater for congestion by having “very advanced load-management systems” in place.
“These systems kick in and make sure that the system doesn’t get overloaded,” he said.
A huge disaster, such as Hurricane Katrina or the London bombings, is the exception, when phone networks are most likely to become congested because of the overload on voice calls.
Imagine phone networks as “pipes”, he says. “If it’s flooded, it will overflow.”
Voice calls take up more space on cellular networks than SMSs do, and “it’s silly to use an SMS service to break down a big network”.
De Villiers believes “people should be responsible” when releasing statements to the public and that “people shouldn’t be afraid of what the report is stating”.