If you get a text message out of the blue telling you you've won a free cruise to an exotic Caribbean location, don't start packing your bags. It's likely just a scam.In its most recent report on SMS spam, Cloudmark notes that scam spam was very popular during the month of May -- especially those "get something free" dodges.Something-for-nothing swindles have always been popular with spammers, because no matter how many times folks are told there's no such as a free lunch, they still believe there is. Last month, though, spammers departed from scam themes they've used in the past.[See also: FTC crackdown on text spammers highlights business threat]Online grifters milking win-free-stuff scams turned their focus to cruise fraud in May, capping what's been a slow decline in free gift card deceptions.Those scams started becoming scarce after the Federal Trade Commission cracked down on the practice in March. At that time, the FTC charged 29 gift card perps with collectively sending 180 million unsolicited SMS messages to consumers, 12% of whom had to pay for the texts.As popular as scams were during the month, bank phishing text spam was even more popular, making up more than 30% of the more than 480 million SMS junk messages sprayed on mobile phones in the United States during the period, according to the messaging abuse solutions provider."Bank phishing attacks tend to come in spikes," Cloudmark threat researcher Andrew Conway said in an interview. "Someone will run it for a few days or a week or so and then vanish."That's because bank phishing runs higher risks for spammers than other cons. "Typical SMS spam comes under the consumer telephone protection act," Conway explained. "It's a civil offense so you're liable for fines and not likely to face jail time."Bank phishing is bank fraud and that you can go to jail for," he said.Nevertheless, bank phishers continue to be drawn to SMS spam. "Phones are trusted devices," Conway noted. "People trust their phones more than they trust their email accounts. It gets more immediate attention, as well."Adult content spam was also popular with SMS spammers last month, making up to almost 25% of junk volumes.Adult content spam typically pretends to be from someone who wants to strike up a friendship with a target. If the target attempts to make contact, they're steered to an adult content site or webcam site where the site operator tries to persuade the target to buy services from the site.One enterprising spammer has tried referring their victims to a chat channel where an artificial person designed along the lines of the old "Eliza" chat bot tries to talk the target into visiting an adult content or webcam site. "It's pretty unsophisticated," Conway noted.Unlike computer spam, SMS spam doesn't contain as many malicious links, however. "With a malicious link in regular email, you can be taken to a site where you can get a drive-by infection," he said. "That doesn't happen as much on a phone."There are Trojans on Android phones, but you have to click on a link, download the app and go through the install process to actually activate it," he explained.Meanwhile, a curious SMS spam campaign was discovered this week by ThreatTrack Security. It masquerades as a message from Google informing its targets that either their Google or Gmail account has been hacked."The messages are being sent out to completely random phones," ThreatTrack Senior Threat Researcher Chris Boyd said in an interview. "A lot of people who have received the message have actually said that they don't have any sort of Google account whatsoever."What's puzzling about the spam is it doesn't seem to have any commercial purpose. People who respond to the message are asked to enter a verification code that was included in the spam, are told that voice mail has been activated and are disconnected."The Google account message may be irrelevant," Boyd said. "It may be a hook to verify that you have an active phone number. Once a number is verified, it can be bombarded with spam messages, scam offers and who knows what,."The problem is that, while the campaign has been going on since March, that kind of activity hasn't occurred yet. "It's quite a mysterious campaign because usually the answer would have appeared by this point," Boyd said.