Apple updated its XProtect security feature to block malware that hit and compromised of Mac computers.
The iWorm malware had infected more than 18,500 OS X machines as of Sept. 29, said researchers at security company Dr. Web. A majority of the computers were in the United States and Canada.
In response, Apple updated its XProtect anti-malware system to detect variants of the worm.
Mac security site The Safe Mac reported the malware infects users via pirated software.
“The moral of the story? Never engage in software piracy,” said The Safe Mac’s Thomas Reed. “This single piece of malware is FAR from the only thing you can get infected with while installing stolen software. Torrents and sites like PirateBay should be avoided at all costs. If you cannot afford to pay for a piece of software or a movie or something similar, do without. Downloading such things for free often come with LOTS of strings attached.”
The malware can collect information on infected systems as well as download files, execute system instructions and take other actions. According to Dr. Web, the worm leverages Reddit to get a list of command and control servers.
“The reddit.com search returns a web page containing a list of botnet C&C servers and ports published by criminals in comments to the post minecraftserverlists under the account vtnhiaovyd,” Dr. Web researchers said. “The bot picks a random server from the first 29 addresses on the list and sends queries to each of them. Search requests to acquire the list are sent to reddit.com in five-minute intervals.”
“While establishing a connection to the server whose address is picked from the list using a special routine, the backdoor attempts to determine whether the server address is on the exceptions list and engages in a data exchange with the server to employ special routines for authenticating the remote host,” Dr. Web researchers said. “If successful, the backdoor sends the server information about the open port on the infected machine and its unique ID and awaits directives.”