Cryptominer Poses as Fake Java Utility

Overview

The SonicWall Capture Labs threat research team analyzed a malware purporting to be a Java utility. It arrives as an installer for Java Access Bridge, but ultimately installs the popular open-source cryptominer, XMRig.

Infection Cycle

The sample arrives as a Windows installer package (msi) file using the following file name:

• JavaAccessBridge-64.msi

Figure 1: Malware installer’s file properties showing Java Access Bridge

Upon execution, a typical installation window pops up.

Figure 2: Fake Java Access Bridge installation window

Meanwhile, the following files are created in these directories:

• /User/Public/Music/ContentStore.bat
• /User/Public/Music/DMIDD11.tmp (certificate file)
• /User/Public/Music/DMIDD12.tmp (certificate file)
• /User/Public/Music/DMIDD13.tmp (certificate file)
• /User/Public/Music/DMIDD14.tmp (certificate file)
• /User/Public/Videos/JavaAccessBridge-64.exe (main XMRig executable)
• /User/Public/Videos/config.json (miner config file)
• /User/Public/Videos/WinRing0x64.sys (WinRing0 driver file used by XMRig)

The Windows command prompt utility is then spawned to execute the batch file name ContentStore.bat which runs the commands seen on the screenshot below.

Figure 3: Contents of the batch file ContentStore.bat

The .tmp files created are all certificate files as shown in the screenshot below.

Figure 4: DMIDD14.tmp contains a certificate

The main cryptominer file is then executed via the command line.

Figure 5: Initial execution of JavaAccessBridge-64.exe via the command line.

XMRig is ran using the configuration in the config.json file.

Figure 6: Configuration in the config.json file

Figure 7: XMRig window running in the background

We urge our users to only use official and reputable websites as their source for software downloads. Always be vigilant and cautious when installing software programs – particularly if you are not certain of the source.

SonicWall Protections

SonicWall Capture Labs provides protection against this threat via the following signatures:

• GAV: Malagent.JAV (Trojan)
• GAV: XMRig.XMR_4 (Trojan)

This threat is also detected by SonicWall Capture ATP w/RTDMI and Capture Client endpoint solutions.

Security News

The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.