Last week, Russian anti-virus firm Doctor Web disclosed a newly discovered piece of OS X malware known as Mac.BackDoor.iWorm that at the time had affected roughly 17,000 machines around the world. While the exact mechanism of infection was unclear, an interesting twist to the story involves compromised machines running search queries on Reddit to obtain instructions about which command and control servers should be used to manage the botnet.
Once connected to a command and control server, the backdoor opened by the malware on the user's system can receive instructions to perform a variety of tasks, from stealing sensitive information to receiving or spreading additional malware.It is worth mentioning that in order to acquire a control server address list, the bot uses the search service at reddit.com, and -- as a search query -- specifies hexadecimal values of the first 8 bytes of the MD5 hash of the current date. 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.
In an effort to address the threat, Apple has now updated its "Xprotect" anti-malware system to recognize two different variants of the iWorm malware and prevent them from being installed on users' machines.
Article Link: Apple Updates Malware Definitions to Protect Against Botnet Threat Coordinated Via Reddit