Mobile security firm Lookout has found a botnet as of December 3, which it is calling SpamSoldier. The threat was detected with the help of one of Lookout's carrier partners, though which has not been said. The botnet spreads through text messages and has not been detected on any major app store.
Two, of many, spam campaigns are shown below:
You've just won a $1000 Target gift card but only the 1st 1000 people that enter code 7777 at hxxp://holyoffers.com can claim it!
Download Grand Theft Auto 3 & Need for Speed Most Wanted for Android phones for free at hxxp://trendingoffers.com for next 24hrs only!
The link downloads an app which installs SpamSoldier and removes the icon from the launcher so you won't see it. Often it installs the free version of the game so that you won't notice that it has been installed. SpamSoldier, meanwhile, is sending out spam in the background through your SMS functions.
The malware attempts to remain hidden by deleting the outgoing texts and by attempting to intercept incoming replies to the texts it sent out. It gets a list of 100 US numbers and the message from a Command & Control server, spams those numbers, then connects back to the C&C for more numbers.
Of course, the main message here: never trust those unsolicited text messages, especially if they contain links.