We found a new cryptocurrency-mining bot spreading through Facebook Messenger, which we first observed in South Korea. We named this Digmine based on the moniker (비트코인 채굴기 bot) it was referred to in a report of recent related incidents in South Korea. We’ve also seen Digmine spreading in other regions such as Vietnam, Azerbaijan, Ukraine, Vietnam, Philippines, Thailand, and Venezuela. It’s not far-off for Digmine to reach other countries given the way it propagates.
Facebook Messenger works across different platforms, but Digmine only affects Facebook Messenger’s desktop/web browser (Chrome) version. If the file is opened on other platforms (e.g., mobile), the malware will not work as intended.
Digmine is coded in AutoIt, and sent to would-be victims posing as a video file but is actually an AutoIt executable script. If the user’s Facebook account is set to log in automatically, Digmine will manipulate Facebook Messenger in order to send a link to the file to the account’s friends. The abuse of Facebook is limited to propagation for now, but it wouldn’t be implausible for attackers to hijack the Facebook account itself down the line. This functionality’s code is pushed from the command-and-control (C&C) server, which means it can be updated.
A known modus operandi of cryptocurrency-mining botnets, and particularly for Digmine (which mines Monero), is to stay in the victim’s system for as long as possible. It also wants to infect as many machines as possible, as this translates to an increased hashrate and potentially more cybercriminal income.
Figure 1: Digmine’s attack chain