One such campaign targeted the 786 area code in Florida. According to census figures, the average household income in that area is around $40,000 and 18 percent of the population is below the poverty line. In other words,a good geographic area for people looking to buy junkers at cut-rate prices.
"They buy cars from poorer neighborhoods and then ship them to South America where second-hand cars still carry a substantial premium," Bradley said in an interview.
Diet tips lure, too
One of the fastest growing spam categories during the second quarter, according to Cloudmark's report, was diet-themed SMS spam. Volumes of that kind of spam tripled during the period, as it reached 12 percent of all spam at the end of the quarter.
Diet spam has a common thread, the report said. All of it contains links to compromised websites. "With a plethora of hacked sites at their disposal, spammers are able to keep their URLs fresh," the report said. "Using these fresh URLs also helps keep spam message bodies fresh to avoid blocking and filtering."
Another trend spotted this year is the use of "over-the-top" services to confuse junk warriors. Those services allow spammers to disguise their campaigns by sending a few messages from many phone numbers.
"Instead of blasting out thousands of messages from a few SIM cards, the spammers are creating large numbers of accounts and then sending smaller volumes per account," AdaptiveMobile's Bradley said.
"Because the volumes are lower, they're much harder to detect. But if you add them all up, they're still sending out significant amounts of SMS spam," he said. "We believe that's a sign that the spammers have had to adapt to carrier improvements in detecting spam and stopping it."
There are those, however, who believe the carriers could do more to stop SMS spam. "I don't think they're doing enough," Dodi Glenn, director of the antivirus lab for ThreatTrack Security, said in an interview.
"They need to work more closely with security vendors, as well as with the manufacturers of the phone, so that a phone has protections installed on it out of the box," he said.
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