Security experts are warning Internet users about a new piece of software that poses as a spyware-removal tool but is actually being used to persuade unsuspecting Internet users to download spyware programs and Trojans.

The program, SpywareNo, is installed on Internet users computer without warning, can be difficult to remove and may be accompanied by malicious programs that hijack victims web browsers, according to interviews with spyware experts. The company behind the new tool claims that it is the victim of unscrupulous online advertisers who bundle the product with noxious wares.

But at least one spyware expert says the new application is just the latest example of so-called "rogue anti-spyware" programs that exploit user naiveté and frustration with spyware.

SpywareNo is advertised as a desktop security software suite, with integrated firewall, application security and intrusion detection features, according to spywareno.com, the program's official Web site.

The program was unknown to spyware experts such as Suzi Turner, who runs the Spyware Warrior Web site.

Turner first learned of the new program after users began complaining about it in a computer security discussion list run by BroadBand Reports, she said.

"These people said that it was running on their computers, but they didn't know how it got there, which is an immediate red flag," Turner said.

One contributor to the forum, who claims to be a U. K. resident and uses the online name "Skanxs," wrote in an e-mail that he has no idea how the program got installed on his system, but that the appearance of SpywareNo coincided with other strange behavior on his computer.

"I did not download any software off the Net when I [first] got infected … on May 14. On [May 18] pop-ups started, and on the 19th [SpywareNo] was in my [Windows] system tray," he wrote.

"When I used add/remove to remove it, it seemed to go, but when I restarted my computer, it was back".

Phillip Gagliardi, an IT administrator at Crobar, a nightclub with locations in New York, Miami and Chicago, and a contributor to the forum, had a similar story.

"The program installed by stealth. … The icon just appeared in my task tray and asked me to run it to make sure I was protected. I did not do so and just shut the program down," he wrote in an e-mail to eWEEK magazine.

Stories like that got SpywareNo added to a list of rogue or suspect anti-spyware products on SpywareWarrior.com, said Eric Howes, a spyware expert and frequent contributor to Spyware Warrior.

Howes said that he and researchers at anti-spyware vendor Sunbelt had a copy of the program installed on a test system while trolling "sleazy porn sites" for malicious software.

But SpywareNo claims that any untoward behavior is the fault of unscrupulous advertisers that the company contracts with to market its program.

"We use affiliated advertisers to [market SpywareNo]. It is a shame that some of our advertisers do not respect the law, but unfortunately we are unable to check them all at the initial stage," wrote a person claiming to be Jessica Simmons, SpywareNo's public relations manager, in an e-mail to eWEEK.