The Windows operating system expert who exposed Sony BMG Music Entertainment use of "rootkit" cloaking techniques last year is now criticizing security vendors Symantec and Kaspersky Lab Ltd. for shipping software that works in a similar manner.

Mark Russinovich, chief software architect with systems software company Winternals Software LP, says that the techniques used by Symantec’s Norton SystemWorks and Kaspersky’s Anti-Virus products are rootkits, a term usually reserved for the techniques used by malicious software to avoid detection on an infected PC. There is "no good justification," for the use of such techniques, Russinovich said. "If the vendor believes that the implementation of their software requires a rootkit then I think they need to go back and re-architect it."

Both Symantec and Kaspersky concede that they have shipped software that hides information from system tools, but told IDG News Service they disagreed with Russinovich’s use of the term rootkit, saying that because their software was not designed with malicious intent, it should not be lumped into the same category.

Still, both companies appeared sensitive to Russinovich’s criticism.

Symantec on Tuesday issued a patch  to SystemWorks that disabled the cloaking feature. And on Thursday, a representative from Kaspersky said that it was possible that his company could take similar action. "I don’t know whether we’ve got a plan to do that, but that’s obviously one thing that we could do here," said David Emm a senior technology consultant with Kaspersky.

Unlike Sony’s XCP (Extended Copy Protection) software, the Symantec and Kaspersky products do not cloak the fact that certain pieces of software are running on the computer. Instead, they hide data.

Symantec’s Norton SystemWorks PC-tuning software uses cloaking techniques to hide a directory of backup files. This technique has been employed by SystemWorks since the 1990s in order to prevent users from accidentally deleting these files, according to Vincent Weafer, senior director for development for Symantec Security Response.

Symantec issued the patch because hackers could conceivably use the SystemWorks cloaking capability to hide files on the system. Weafer described this possibility as a "low risk" threat, saying that most security software would be able to detect these cloaked files. "The intent of this feature was for good," he said. "But we need to look at these technologies and say, ’What is the potential for harm?’ Even if it’s a low risk, the right thing to do is remove them."

Kaspersky’s use of cloaking software is more recent. With v