Researchers observed an attack campaign exploiting CVE-2019-2725 and abusing certificate files to deliver a Monero miner.
Trend Micro discovered that the Monero miner campaign begins by exploiting CVE-2019-2725, a deserialization vulnerability that affects Oracle WebLogic Server, after arriving on a target machine. It uses this exploit to execute a command for implementing a series of routines. Among these, the attack uses a PowerShell script to download a certificate file from its command-and-control (C&C) server.
With the help of CertUtil, the campaign decodes the certificate file to ultimately reveal a PowerShell command. This resource downloads and executes another PowerShell script from memory that, in turn, downloads and executes various files. Those items include Sysupdate.exe, the payload for the Monero miner, and Update.ps1, a PowerShell script that executes every 30 seconds.
An Uptick in Cryptomining Attacks
This isn’t the only campaign involving a Monero miner in recent months. In April 2019, for instance, Trend Micro spotted a wave of attacks that leveraged EternalBlue and PowerShell to deliver a Monero cryptocurrency miner. It was less than two months after that when the company discovered BlackSquid, a new malware family capable of exploiting eight notorious vulnerabilities including EternalBlue and DoublePulsar to install the XMRig Monero-mining malware.
In May 2019, Guardicore Labs observed that the Nansh0u cryptomining campaign had successfully infected more than 50,000 servers belonging to companies in various industries.
How to Defend Against an Unwanted Monero Miner
Security teams can better avoid unwanted Monero miners by using threat feeds in tandem with a security information and event management (SIEM) tool to watch for malicious traffic that could be looking to exploit vulnerabilities. Organizations should also conduct a thorough risk assessment to measure and formulate an appropriate response to the cryptomining risks facing the network environment.