Security researchers report that the newest version of NRSMiner crypto-mining malware is causing problems for companies that haven’t patched the EternalBlue exploit.

Last year, the EternalBlue exploit (CVE-2017-0144) leveraged Server Message Block (SMB) 1.0 flaws to trigger remote code execution and spread the WannaCry ransomware. Now, security research firm F-Secure reports that threat actors are using this exploit to infect unpatched devices in Asia with NRSMiner. While several countries including Japan, China and Taiwan have all been targeted, the bulk of attacks — around 54 percent — have occurred in Vietnam.

According to F-Secure, the newest version of NRSMiner has the capability to leverage both existing infections to update its code on host machines and intranet-connected systems to spread infections to machines that haven’t been patched with Microsoft security update MS17-010.

Eternal Issues Facing Security Professionals

In addition to its crypto-mining activities, the latest version of NRSMiner is also capable of downloading new versions of itself and deleting old files and services to cover its tracks. Using the WUDHostUpgrade[xx].exe module, NRSMiner actively searchers for potential targets to infect. If it detects the current NRSMiner version, WUDHostUpgrade deletes itself. If it finds a potential host, the malware deletes multiple system files, extracts its own versions and then installs a service named snmpstorsrv.

Although this crypto-mining malware is currently confined to Asia, its recent uptick serves as a warning to businesses worldwide that haven’t patched their EternalBlue vulnerabilities. While WannaCry infections have largely evaporated, the EternalBlue exploit/DoublePulsar backdoor combination remains an extremely effective way to deploy advanced persistent threats (APTs).

How to Curtail Crypto-Mining Malware Threats

Avoiding NRSMiner starts with security patching: Enterprises must ensure their systems are updated with MS17-010. While this won’t eliminate pre-existing malware infections, it will ensure no new EternalBlue exploits can occur. As noted by security experts, meanwhile, a combination of proactive and continual network monitoring can help identify both emerging threats and infections already present on enterprise systems. Organizations should also develop a comprehensive security framework that includes two-factor authentication (2FA), identity and access management (IAM), web application firewalls and reliable patch management.

EternalBlue exploits continue to cause problems for unpatched systems. Avoid NRSMiner and other crypto-mining malware threats by closing critical gaps, implementing improved monitoring strategies and developing advanced security frameworks.