The internet mayhem is thought to have been linked to fake or leaked nude celebrity photos, in the wake of a scandal which saw nude photos of a number of female celebrities hacked from a cloud storage system and posted to an online message board.
Spark said it was aware that when people clicked on some celebrity nude snaps, they inadvertently installed the kind of software that created distributed denial of service (DDoS) attacks such as this weekend's.
However, today a spokeswoman said services were coming back online.
"The return to a normal browsing experience is due to a combination of, one, us taking a number of steps to mitigate the issue over the past two days, and, two, the pressure on our network, which has been coming from some customer's devices being used in Denial of Service attacks aimed at overseas networks, subsiding," she said.
"Our work has included identifying and neutralising the effect of the small number of customer connections that had been exploited by cyber criminals to send vast amount of traffic through our network to overseas destinations.
"We are now reaching out to the identified customers to work with them on closing any vulnerabilities on their devices."
The company also offered its "sincere apologies" to the customers who had been affected by the outage.
But the spokeswoman said there was no guarantee it would not flare up again.
"These sorts of incidents are dynamic in nature ? tactics by international cyber criminals are constantly changing and so we'll continue to remain vigilant and monitor the situation," she said.
"Like all ISPs [internet service providers], we don't guarantee that these sorts of incidents won't intensify again or take a different form."
She urged customers to keep their devices and security suites up-to-date to ensure they are not vulnerable to malware or viruses.
