Apple has updated its Xprotect anti-malware blacklist tool to address a new trojan for OS X that surfaced just two days ago. The trojan, aptly named SMSSend, looks like a normal program installer, but tricks users into sharing their cell phone number and then entering a code sent via text. After doing so, the user is signed up for a subscription service that charges their monthly phone bill. Although similar trojans have been found on other operating systems, this is the first of its kind to target Mac users — though it does require a lot of effort from the user to fall victim. Apple recently softened its previous marketing claims that Macs are immune to viruses, and even attended this year's Black Hat conference. Combined with the company's quick response to this trojan, Apple has proved that it's both serious and quick on its toes when it comes to user security.