Highly evasive cryptocurrency miner targets macOS

Pierluigi Paganini February 24, 2023

Researchers warn of an evasive cryptojacking malware targeting macOS which spreads through pirated applications

Jamf Threat Labs researchers reported that an evasive cryptojacking malware targeting macOS was spotted spreading under the guise of the Apple-developed video editing software, Final Cut Pro. 

Trojanized versions of legitimate applications are being used to deploy XMRig cryptocurrency miner on macOS systems.

“Further investigation revealed that this malicious version of Final Cut Pro contained a modification unauthorized by Apple that was executing XMRig in the background.” reads the analysis published by the experts.

At the time of its discovery, the sample analyzed by the experts was not labeled as malicious by any security vendors on VirusTotal. Today, many malicious applications continue to go undetected by most AV vendors.

This malware relies on the i2p (Invisible Internet Project) anonymization network for communication. The malicious code uses i2p to download malicious components and send mined currency to the attacker’s wallet.

The researchers noticed similarities with other examples reported by Trend Micro in February 2022. However, the Jamf Threat Labs pointed out that there were still discrepancies and unanswered questions, such as why the sample they found was so evasive.

“We downloaded the most recent torrent with the highest number of seeders and checked the hash of the application executable. It matched the hash of the infected Final Cut Pro we had discovered in the wild. We now had our answer.” continues the analysis. “We observed that the torrent was uploaded by a user with a yearslong track record of uploading pirated macOS software torrents, many of which were among the most widely shared versions for their respective titles”

The Jamf’s report revealed that the tainted app was distributed through Pirate Bay since at least 2019.

Jamf was able to identify the various samples of the malware distributed through pirated applications, determining when they appeared in the torrent community, when they started being submitted to VirusTotal, and when security vendors started to detect the malware. This allowed the cyber security firm to understand the malware evolution and the tactics and techniques used by the authors to avoid detection. The experts identified three generation of malware since August 2019.

macOS cryptocurrency miner

The first-generation samples were using the AuthorizationExecuteWithPrivileges API to gain elevated privileges and install the Launch Daemon to gain persistence. Later first generation samples changed to a user Launch Agent, which would not require the conspicuous password prompt. The second-generation samples started relying on the user launching the application bundle to start the mining process, instead of gaining persistence.

The most recent variants of the miner hide the malicious i2p components within the application executable using base64 encoding.

The report states that despite the security improvement introduced with the latest macOS version Ventura, it was still possible to execute cryptocurrency miners on the infected system.

“On the other hand, macOS Ventura did not prevent the miner from executing. By the time the user receives the error message, that malware has already been installed.” concludes the report. “It did prevent the modified version of Final Cut Pro from launching, which could raise suspicion for the user as well as greatly reduce the probability of subsequent launches by the user.”

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Pierluigi Paganini

(SecurityAffairs – hacking, malware)

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