Researchers spotted an attack campaign that seeks out publicly exposed Elasticsearch databases and servers to deliver a distributed denial-of-service (DDoS) botnet.

In an attack wave spotted by Trend Micro, the DDoS botnet campaign began by scanning for exposed or unsecured Elasticsearch databases and servers. One instance of the attack even went so far as to exploit CVE-2015-1427, an older vulnerability that affects the Groovy scripting engine of Elasticsearch. Either way, the campaign used a dropper to run the script s67.sh so it could define which shell to use and where to find it before attempting to stop the firewall. The campaign then ran s66.sh, a second-stage script that removed traces of the initial infection and killed any other cryptocurrency mining processes before downloading the final binary.

The campaign’s binaries revealed a backdoor variant that functioned similarly to BillGates malware. Researchers observed this threat stealing system information, enslaving infected machines and launching DDoS attacks. The backdoor also came with the ability to exploit CVE-2017-5638, a remote code execution (RCE) vulnerability in Apache Struts 2.

A Growing List of Elasticsearch Security Incidents

This isn’t the first attack to prey on exposed Elasticsearch databases and servers. In November 2018, for instance, HackenProof unearthed an IP with a publicly accessible Elasticsearch cluster that exposed the personal data of nearly 57 million U.S. citizens. Two months later, Security Discovery observed an unprotected Elasticsearch server containing 24 million records of personal information.

Most recently, in April 2019, The Hacker News reported on tens of thousands of exposed Kibana instances that, in turn, made the Elasticsearch databases and servers with which they worked publicly accessible.

How to Defend Against a DDoS Botnet

Security professionals can help defend against attack campaigns that seek to deliver a DDoS botnet by using a comprehensive vulnerability management program to prioritize software patches based on the level of risk posed by known security weaknesses. Companies should also work to defend their systems against DDoS attacks using next-generation firewalls, anomaly detection and other tools.