The threat, known as SpamSoldier, hides in fake messages offering free games
Researchers at security company Cloudmark have discovered a new Android phone spam botnet which uses infected handsets to send bulk SMS spam messages without the user's permission.
The threat, dubbed SpamSoldier, was also detected by Lookout Security earlier this month. The company said that SpamSoldier is primarily spread through SMS messages that advertise free versions of popular paid games like Need for Speed or Angry Birds Space.
Researchers at Cloudmark added that SpamSoldier first appeared on 26 October this year, and was being spread under the guise of antimalware for mobile, which was downloaded from sites on a server in Hong Kong offering free games.
According to researchers, the schemer behind the attack changed its approach in November, with the free games scam which simply attempts to get the botnet to spread.
Researchers found that the malware communicates with the C&C server using HTTP, and a message as well as a list of 50 numbers are returned. It then checks with the C&C server every 65 seconds for more numbers.
Cloudmark security researcher Andrew Conway said that compared with PC botnets this was an unsophisticated attack.
"However, this sort of attack changes the economics of SMS spam, as the spammer no longer has to pay for the messages that are sent if he can use a botnet to cover his costs," Conway said. "Now that we know it can be done, we can expect to see more complex attacks that are harder to take down."