While Craigslist has always been a favorite social engineering theme for scammers, Symantec has identified another on-going SMS spam campaign abusing Craigslist’s popularity. The scam tricks users into installing free and legitimate open source software on their PC by leveraging phone numbers posted on Craigslist ads. The software comes bundled with additional software that will allow scammers to make money through affiliate programs.
Figure. How the SMS spam redirects users to download open source software
The first stage of the scam involves the victim receiving an SMS text message on their device. Online research suggests that the scammers are harvesting phone numbers directly from online Craigslist postings for this scam campaign. The sale of spamming and harvesting tools, which automate the harvest of phone numbers, is common on underground forums.
When a user follows the link provided in the SMS sent to them they are informed: "Device not compatible. Please view from a desktop or laptop computer." If a user then navigates to the link from their PC, they are informed that they need to install the GIMP Viewer legitimate open source software). Attempting to install GIMP does not take the user to the official GIMP website, but instead to a different website offering to install GIMP with the option to install several other pieces of software. If the additional software is installed, the scammers make money from affiliate commissions.
In this scam users are being tricked into installing unwanted software onto their computers and affiliate programs are being abused by scammers. The scammers could also easily switch tactics and trick victims into installing malware on their computers.
To avoid being a victim of this and other scams, be cautious when receiving any unsolicited SMS text messages and avoid downloading and installing any type of software unless it comes from an official and reputable site. Symantec also recommends users everywhere install a mobile security app and desktop antivirus protection, such as Norton Mobile Security and Norton antivirus.