Malware attacks to steal data off target computers or take a rival offline are "very sinister", the Telecommunications Users Association (Tuanz) says.
Spark customers are facing continuing internet outages as viruses disrupt the broadband network.
The company has apologised for the ongoing issues saying a "high volume of traffic is affecting customers' ability to browse on broadband and mobile" and it says the cause is likely to be a handful of customers whose computers are affected by malware.
Tuanz spokesman Chris O'Connell says the malicious software (malware) creates a denial of service attack with so many requests that the server falls over and can't be accessed any more.
He says Spark has over 600,000 customers and trying to find where in the network the spikes in activity are occurring is a "real needle in a haystack".
"The hackers and cyber criminals are always trying new techniques...writing new code and trying to get out there with new hacks," Mr O'Connell told ONE News.
"It doesn't matter how big you are, it's a constant battle of keeping your resources up to date and being aware of what's going on."
Mr O'Connell says the hack of the Whale Oil website which led to the 'Dirty Politics' saga is believed to have occurred while it was under a denial of service attack last year.
"People pay organised criminals to do this, it's very sinister."
Meanwhile Spark says it is working as fast as it can to fix the problem, and is offering advice for customers who need to get online urgently.
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