Security house Kaspersky Lab scored an impressive legal win that saw it not only beat a patent troll, but actually collect money from the plaintiff in the process.

The Russian antivirus vendor said that it collected a $5,000 payment to agree to drop a patent infringement case where it was the defendant, after the litigator agreed they had no hope of winning their claim.

Founder Eugene Kaspersky said his company was first notified of the infringement claim in 2016, when Wetro Lan told the security vendor they were infringing on US Patent 6,795,918.

The patent, described has a method for "filtering data packets by providing non-user-configurable authorization data," has been long known as a favorite cudgel for dubious patent claims and was decried as being almost identical to the description of an ordinary firewall.

Suspecting Wetro Lan was just looking for a quick settlement payout, Kaspersky said his company responded instead by preparing to fight the case and refusing the plaintiff's offers to settle out of court. This meant that if Kaspersky won, the patent would be invalidated and the company would be entitled to reimbursement of legal costs.

The key, said Kaspersky, was the knowledge that US courts require both parties to agree when a case is dismissed, meaning Kaspersky could keep the matter tied up in the court at least through trial.

"Now, as per the usual script, this would have gone on until its demand was for a pittance. But this time we decided to tear up the rule book: we issued it with a counter demand sum – $10,000 – for us to drop the lawsuit (remembering that the court only dismisses a lawsuit if both parties agree thereto)," Kaspersky explained.

"And at just $10,000 it was a bargain for the price, for otherwise we would continue our meetings in court on which the troll would spend a lot more money and energy (on an unwinnable case), and run the risk of having to pay our court costs."

Eventually, as Kaspersky tells it, Wetro Lan was able to get away with only paying Kaspersky a $5,000 fee. The founder conceded that was less than the company's own legal costs, but says the message he sent was the most important thing in a time when many others will simply pay off patent trolls.

"These are very unusual results in the USA. Accordingly, they are results that tend to keep the shrewder trolls off our back," Kaspersky wrote.

"The less shrewd, however, still keep coming, not even taking the time to find out about our successful anti-troll reputation – or even just our basic anti-troll slogan: 'We fight them to the last bullet – their last bullet.' Perhaps if they did, they too would stay away. But they don't. So they get stung."

Kaspersky is not alone in its efforts to turn the table on patent trolls. Earlier this year, network services giant Cloudflare kicked off a legal campaign to completely wipe out a law firm it saw as a particularly threatening patent troll.

The Kaspersky tactic, by comparison, is far more tame, but could be a much easier blueprint for other companies to follow in dealing with patent troll claims. ®