Sirius XM Radio has quietly fixed a bug in its satellite radio system that provided a way for former subscribers to gain free access to the Sirius service since 2002, according to security vendor TippingPoint Technologies.

TippingPoint found out about the issue when it was reported to the company's Zero Day Initiative, which pays hackers for technical details on security bugs, said Terri Forslof, TippingPoint's manager of security response. TippingPoint relayed its information on the issue to Sirius on July 10, she added.

The situation shines a light on what could become a new problem for the radio network, following the July merger of Sirius and XM: satellite piracy. Industry watchers say that with a combined audience of more than 18.5 million Sirius XM subscribers, pirates may now have the incentive they need to create illegal devices that can receive Sirius XM signals.

The July 10 problem, which Sirius has apparently now resolved according to TippingPoint, was in the deactivation process used to cancel subscriptions. "It's really an oversight on Sirius's side," she said. "It's just kind of sloppy, and in the end it really hurts their bottom line."

For example, the flaw could have been exploited to build black market satellite radio receivers that would never be deactivated, Forslof said. Although TippingPoint does not know how many people are aware of the issue, the person who reported the bug to TippingPoint said that "multiple people were doing this," she said.

TippingPoint, a division of 3Com, lists the issue on its Web site as having medium severity, but the flaw does not affect the security of Sirius users, Forslof said. Also, it does not affect devices designed to use XM Satellite radio, which was recently acquired by Sirius XM.

Sirius XM had little to say about TippingPoint's findings. "Sirius XM does not comment on security issues though we do invest in our technologies to insure our service is protected for our subscribers," the company said in an e-mailed statement. "We are confident in the effectiveness of our technology."

It is not clear exactly when Sirius fixed the bug or for how long it was possible to exploit it. Sirius first began offering service under that name in 2002 and the bug apparently existed then, according to TippingPoint.

A search of online forums turns up anecdotal evidence that some Sirius subscribers may have been able to evade the company's deactivation signals and at least one reference to a cracked Sirius Sportster radio, selling for US$400.

Whether that US$400 Sportster actually works is doubtful, according to Jim Shelton, an independent consultant who finds and tests illegal satellite equipment. He said he has not seen Sirius or XM devices for sale recently from the sources he uses for his investigations. "If there was something legitimate out there, I would have come across it by now," he said.

But he said that pirates are probably paying close attention to any new radio equipment that comes out following the XM-Sirius merger. "They're definitely a big target," he said. "That's definitely a base that you could sell into."

Piracy already costs the satellite TV industry hundreds of millions of dollars each year, according to Jimmy Schaeffler, chief service officer with The Carmel Group, a digital entertainment consulting firm. With some TV packages priced at close to $100 per month, (Sirius Everything Plus service is $16.99 per month) pirates have focused on satellite TV.

However, Schaeffler views a move to satellite radio piracy as "inevitable," now that Sirius and XM have merged. That's because pirates can now reach a much larger market of nearly 20 million Sirius XM radio subscribers. "A pirate can find true value from figuring out how to hack them," he said.