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Mac Malware Delivered via Firefox Exploits Analyzed

A researcher has conducted a detailed analysis of the two pieces of Mac malware delivered recently by threat actors to cryptocurrency exchanges via two Firefox vulnerabilities.

Updates released by Mozilla last Tuesday and Thursday for Firefox addressed two actively exploited vulnerabilities. The flaws, CVE-2019-11708 and CVE-2019-11707, allow an attacker to remotely escape the sandbox and execute arbitrary code.

The macOS malware delivered to Coinbase and other organizations involved with cryptocurrencies has been analyzed in detail by Patrick Wardle, a researcher who specializes in the security of Apple products.

Wardle has obtained samples of the malware and performed an analysis of their installation routines, persistence mechanism and capabilities.

The first piece of malware, delivered as a file named Finder.app, is tracked as OSX.NetWire.A. Netwire, also known as Wirenet, is a piece of malware that emerged in 2012, designed for stealing passwords from Linux and OS X systems.

According to Wardle, the malware involved in the recent Firefox zero-day attacks is designed to run on many versions of the Apple operating system, including all the way back to OS X 10.5 Leopard, released in 2007.

Once it infects a device, the malware collects information about the compromised system. It allows the attacker to take full control of the system and send commands for performing file-related actions, interacting with processes, capturing screenshots, generating synthetic keyboard and mouse events, and uninstalling itself.

The second piece of malware has been linked to Mokes, a threat that Kaspersky first analyzed in 2016. The original Mokes was a cross-platform malware capable of capturing screenshots, spying on the user through the built-in webcam and microphone, logging keystrokes, and stealing files.

The new malware, which Wardle has dubbed OSX.Mokes.B, has many of the same capabilities, along with significant similarities in code.

Despite the fact that both malware samples have been used in high-profile attacks, they still have fairly low detection rates on VirusTotal at the time of writing (Netwire, Mokes). On the other hand, that does not necessarily mean that advanced cybersecurity products would not detect them once they landed on a machine. Furthermore, Apple’s XProtect system can detect the Netwire sample based on a Yara signature added by the company in 2016 for an older version of the malware.

Security researcher Vitali Kremez has found some links to previous campaigns, along with some evidence suggesting that Windows malware may have also been delivered in the recent Firefox attacks.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.