A Microsoft Corp. employee impersonated a private technology consultant in order to smear America Online Inc.

But Richard Smith, a security expert who received the message via e-mail, said today that if the allegations against AOL are true, then users' computers could be at risk.

The New York Times reported Friday that Microsoft (MSFT) officials acknowledged one of its programmers sent an e-mail accusing AOL (AOL) of irresponsible behavior in the battle over instant messaging.

Microsoft officials could not immediately be reached for comment this morning.

Battle of the superpowers

Microsoft and AOL have been at each other's throats since Microsoft released a program last month that allowed users to contact consumers using AOL's popular Instant Messenger service.

AOL has accused Microsoft of improperly accessing its servers. Microsoft replied that AOL was unfairly closing off its technology to developers.

The two have since been playing a cat-and-mouse game, with AOL putting up blocks against Microsoft's program, and Microsoft workers developing workarounds to get access.

Smith, president of Phar Lap Software, said Friday that he got an e-mail Wednesday night from someone claiming to be Phil Bucking of Bucking Consulting. The e-mail accused AOL of commiting a "heinous and risky action" and putting users at risk in its attempts to block Microsoft.

"I did some Web searches on Bucking and it came up blank. That set off some alarm bells," Smith said.

Smith said he was able to trace the e-mail back to a Microsoft proxy server.

While Smith decried "being used" by the Microsoft employee, he said he was concerned about the claims made in the e-mail.

The e-mail alleges that, in its attempts to block Microsoft, AOL sent snippets of code to AIM clients, exploiting a "buffer overrun" to execute the code.

If that's true, Smith said, then "what that means is AOL has a back door into customers' computers where they can run stuff."

"I don't think any software should have a back door," he added. "They need to come clean. They've got to say yes or no."