As market share of Apple's ARM based Mac computers has increased, so too have efforts to compromise them by previously uninterested hacker groups. A recent string of malware created specifically for macOS has shown that these groups are turning their gaze toward the generally well protected Mac ecosystem. One of these new malware threats, discovered by Jamf Threat Labs and dubbed 'RustBucket,' acts as a simple third-party PDF viewer. The application itself does nothing malicious until a specific PDF is opened which includes an encoded key that triggers a connection to be made between the attacker's server and the victim's Mac, and a small malicious payload to be downloaded. The initial payload begins running system recon commands to determine the machine information, and then downloads a third stage payload which gives the attackers further access to the underlying operating system. All stages after the user opens the PDF are run silently in the background. The PDF viewer used as the catalyst for this hack does require manually overriding Apple's Gatekeeper as it carries no signature, so the obvious step to mitigate this attack is to not use third-party apps or services aside from those curated on Apple's App Store.

The second macOS malware of the week was discovered by Cyble Research and Intelligence Labs (CRIL) being offered for a paltry $1,000 USD per month on a Telegram channel, with the malware going by the name "Atomic macOS Stealer" or "AMOS." This malware has capabilities to scrape keychain passwords, system information, files from the desktop and documents folders, the macOS user password, browser auto-fills, passwords, cookies, wallets, and stored credit card info. The malware is especially adapted to go after cryptowallets with Cyble citing examples such as Electrum, Binance, Exodus, Atomic, and Coinomi. Cyble notes that they've seen the malware receiving active development to improve its capabilities and the threat actors even offering management software and web panels for keeping track of victimized machines, all with a logging system that dumps to Telegram. The current attack vector is a simple Golang.dmg file which installs the malware, so this does appear to require direct machine access. However once installed, "AMOS" does its handiwork without detection and sends a compressed file off to the attacker's server with all the information it collected.