Facebook is a place where most people share status updates, photos and videos — not pornography. However, a malicious Trojan that may look like a piece of adult entertainment in a friend’s post is already affecting countless members of the social networking service.

Malware Targets Facebook Users

The Trojan was first reported by security researcher Mohammad Reza Faghani, who published the details on the SecLists industry message board. He estimated more than 110 million Facebook users have already been infected in a 48-hour period. He characterized the attack as a “magnet” technique because it involves cybercriminals tagging a victim’s Facebook friends. Those friends see a post pointing to a porn video, which then demands an update of Adobe Flash to continue. Updating the tool causes the malware to be immediately downloaded.

A story on Threatpost included a response from Facebook saying it was aware of the Trojan and was exploring ways to stop URLs containing malicious content from being spread through its service. The problem, of course, is that by tagging friends of a given victim, the attack can spread much like a highly viral piece of legitimate social media content.

Given the massive international nature of Facebook’s installed base, it’s unsurprising that cybercriminals would start to see it as a vehicle through which they can more easily distribute malware. It has already been used to perpetrate credit card fraud and even solicit donations to a phony children’s charity. That said, the social engineering aspects of the scam are not unlike those that use email. It’s all based on knowing the person who is supposedly offering up an enticing piece of content and the tendency of consumers to innocently obey commands to get the latest versions of various online multimedia tools.

Tips for Trojan Prevention

Although consumers can’t do much to avoid such attacks other than remain suspicious of Facebook posts containing a porn video, CSO Online had some practical advice. It suggested Facebook users could adjust their privacy settings so they need to grant permission to display any content in which they are tagged to their Timeline. At the very least, that could curb the speed at which this particular Trojan spreads.

In fact, that might not be the only reason for Facebook users to take a look at their privacy policies. According to SC Magazine, as of January, the social network has inserted a clause that could let it monitor a user’s surfing habits and exchange the details with related apps it owns, such as WhatsApp and Instagram, to serve up more contextualized ads. That may be harder to justify unless Facebook can prove it can help users fend of unauthorized third parties from targeting users through scams. In other words, if Facebook wants access to more information about its users, it may need to prove it’s a true friend.