OzEmail yesterday revealed it has tracked the source of a hacker attack on its international network last Friday to two US-based service providers.
According to company spokesman Michael Ward, OzEmail users were denied access to Internet and e-mail services last Friday afternoon as the company's Internet links were flooded with data from an unknown source.
Ward said OzEmail discovered the attack - known as a "denial of service" - travelled across its Concentric and UUNet links from the US.
However, he said while the networks could be identified, it was difficult to source the individual attacker.
"We think we know what it is," he said. "Someone got pretty pissed off, one of our users."
Ward said OzEmail is considering the installation of e-mail filters to protect its users against further attacks in the future.
When asked what effect the attack had on OzEmail's corporate Internet access business, he said: "We had virtually no complaints, but that reflects this is not a busy time of year."