Facebook scammers have started redirecting victims through Amazon's cloud in order to bypass malicious URL filters, according to security researchers from antivirus vendor F-Secure.
One Facebook survey scam recently analysed by F-Secure uses malicious browser extensions to hijack Facebook accounts and post spam messages on their walls.
The messages contain Bit.ly shortened links that appear to lead to interesting videos. However, in reality they point to redirect scripts hosted on Amazon's S3 service that send victims to a fake Facebook page.
The rogue page displays a video player image, which when clicked, prompts a window asking users to participate in a survey. Scammers earn money through affiliate marketing schemes for every user who agrees to participate.
The scam is distributed through fake extensions for Google Chrome and Firefox that are passed to victims as YouTube player updates. Users are asked to download and install these in order to watch the videos they clicked on.
According to F-Secure's chief research officer, Mikko Hypponen, scammers prefer to redirect users through links on Amazon's cloud because its domain name and corresponding IP addresses have a high trust rating. This increases their chances of tricking malicious URL filters like those used by Bit.ly or Facebook.
While the use of Amazon S3 links in Facebook scams is a relatively new technique, the hosting of malware on the popular cloud service is not a new practice. The Amazon S3 hosting service is not very expensive and a lot of cybercriminals are probably able to afford it.
However, some of them prefer to steal login credentials from existing Amazon customers and abuse their accounts, Hypponen said. "Some of the malcreants exclusively use accounts belonging to other people. Others create new accounts with stolen credit cards. Some create valid accounts and pay for them."