OSX/CreativeUpdater Cryptominer Distributed via MacUpdate

OSX/CreativeUpdater is a macOS cryptominer that was distributed in early February 2018 via compromised download links on the popular MacUpdate website. The attack involved modifying download links for applications like Firefox, OnyX, and Deeper to point to a hacker-controlled URL (download-installer.cdn-mozilla.net) serving a trojanized version of the application. This trojanized application, disguised as a legitimate application and signed with an Apple Developer ID (Ramos Jaxson), bypasses Gatekeeper’s default security settings. Once executed, the malware installs a persistent payload designed to mine Monero, impacting system performance and potentially allowing for future customized payloads. The use of MacUpdate as an infection vector allowed the malware to potentially infect a large number of macOS users.

Attack Chain

1. User visits MacUpdate and downloads a popular application (e.g., Firefox) from a compromised link.
2. The user downloads a signed disk image (.dmg) containing a trojanized application bundle.
3. The user mounts the disk image, bypassing Gatekeeper due to valid developer signature (Apple Developer ID: Ramos Jaxson).
4. The user executes the trojanized application (e.g., Firefox.app), which in turn executes a script file located within the application’s Resources directory.
5. The script downloads a zip file (mdworker.zip) from a remote server (https://public.adobecc.com/files/1U14RSV3MVAHBMEGVS4LZ42AFNYEFF) and unzips it into the user’s Library folder (~/Library/mdworker/).
6. The script creates a LaunchAgent file (MacOSupdate.plist) in ~/Library/LaunchAgents/ to achieve persistence.
7. The LaunchAgent loads, which in turn downloads another plist file (MacOS.plist) from a remote server (https://public.adobecc.com/files/1UJET2WD0VPD5SD0CRLX0EH2UIEEFF).
8. The second plist file (MacOS.plist) executes the ‘mdworker’ binary, which is the MinerGate command-line cryptominer (minergate-cli), configured to mine Monero (XMR) using specific email addresses and, in some cases, a SOCKS proxy.

Impact

Successful infection leads to the installation of a Monero cryptominer on the victim’s macOS system. This results in high CPU usage and reduced system performance. The malware periodically connects to minergate.com, passing the email address as a login. The compromised applications included Firefox, OnyX and Deeper. Although the exact number of victims is unknown, the use of the popular MacUpdate platform as a distribution vector suggests a potentially wide impact.

Recommendation

• Deploy the Sigma rule “Detect Suspicious MacOSupdate.plist Launch Agent” to detect malicious launch agent files in the ~/Library/LaunchAgents/ directory.
• Block the following domains at the DNS resolver to prevent the downloading of malicious payloads: public.adobecc.com and minergate.com (IOC table).
• Monitor process execution for ‘mdworker’ running from the ~/Library/mdworker/ directory and alert if found (Sigma rule).
• Inspect network connections for connections to the IP address 104.236.13.101 on port 1080, as this was used as a SOCKS proxy (IOC table).