McDonald's fix: a single link to Trend Micro's "Housecall" (http://housecall.trendmicro.com/) online virus scanning service and an open offer to replace infected players for free also won praise over Apple's response: a bunch of links to free antivirus software trials, including Microsoft's OneCare program, Poon wrote.

"Steve, if you need someone to advise on how to improve your quality checks, feel free to contact me," Poon said, referring to Apple CEO Steve Jobs.

Software companies have long known about the potential to introduce viruses and other malicious code during the manufacturing process, and have developed procedures to catch such infections.

Two such episodes in a week might indicate that malicious hackers have figured out that consumer device makers are less vigilant in their oversight, said Dennis Szerszen, vice president of marketing and corporate strategy at SecureWave, an end point security software vendor.

Apple may have had more lax oversight around the iPod because it wasn't software and wasn't, in itself, targeted by malicious code, he said.