While McAfee had no immediate comment, others in the industry were skeptical of Damballa's statements concerning the antivirus software testing.

Vendor statements about testing other vendors' products and finding them wanting always have to be deeply questioned, says Graham Cluley, senior technology consultant at Sophos. He adds that customers would do better to put more credence in testing done by independent labs such as West Coast Labs, ICSA Labs or AVtest.org.

(Separately, Sophos said on Monday that by analyzing the Conficker code, it believes the malware can be expected on Friday, March 13, to launch a search for a Web site URL owned by that directs traffic to the main Southwest site.)