A ransomware-based malware scam allowed Russian cybercrooks to fleece an estimated 2,500 surfers to the tune of almost $30k.
Unwary smut-seekers visiting a porno site found their machines disabled by a Trojan. They were told to solve the problem by sending an SMS to a premium-rate number at a cost of $12 (360 roubles), and a substantial minority did so.
Surfers might have protected themselves by regularly backing up important data, using anti-virus defences or (perhaps best of all) avoiding the temptation to trawl the web's lower depths.
Such ransomware campaigns crop up periodically, often in Russia. However, an analysis by Trend Micro, published on Wednesday, is the first we've come across to put a figure on the number of victims or profits from this type of illicit activity.
The malware strain associated with the scam, identified by Trend as the Rixobot-A worm, was apparently downloaded for one location more than 137,000 times in December 2010 alone. The security firm was able to get into a website database used by the crooks to chart the success of their campaign, in particular its "conversion rate" between malware click through rates and revenues.
The scam brought in almost $30K - US$29,435 or 901,245 RUR - in revenues in just five weeks.
"In our research, we were able to access a panel that was used to keep track of the specific income generated by at least 60 phone numbers used in ransomware campaigns," writes Nart Villeneuve, a senior threat researcher at Trend Micro.
"The list contains 60 phone numbers displayed by the ransomware and used to receive funds from victims."
"Based on our findings, this campaign was able to generate 901,245 RUR (US$29,435) over the last five weeks. With a payment of approximately US$12 per transaction, this indicates that 2,500 people paid the ransom. Users are thus advised to be more wary about their online activities."
Trend Micro's write-up of the scam, containing screenshots of the control panel and a screenshot from an infected machine, can be found here. ®