Spurred by security researchers' concerns, Symantec reevaluated a feature of Norton SystemWorks that creates a folder hidden from the Windows operating system and released a patch this week to make it visible.

The feature, part of Norton Protected Recycle Bin, hid a directory from the Windows operating system to protect temporary copies of files that the user had deleted or modified from accidental erasure. Because a malicious attacker could hide files within the folder and avoid antivirus scanning, Symantec, which owns SecurityFocus, reconsidered the value of hiding the folder and designed a patch to make the folder visible to Windows functions and applications, the security company said in an advisory.

The security implications of the issue were brought to the company's attention by the same two security research groups that raised issues with the surreptitious hiding features of music giant Sony BMG's copy protection software. Antivirus firm F-Secure warned Symantec about the issue nearly 10 months ago and Mark Russinovich, the chief software architect of Winternals, discovered the same problem more recently.

While the effects of Symantec's decision to hide the folder are similar to the Sony BMG case, the antivirus company used stealth techniques similar to the "rootkits" used by malicious attackers to protect the user, not its own intellectual property, Mikko Hyppönen, chief research officer for F-Secure, said in a blog post. F-Secure has discovered other legitimate applications that also use stealth techniques to hide files for one reason or another.

Sony BMG recently agreed to a settlement to six lawsuits against the company filed in the Southern District of New York.