More than 39,000 unauthenticated Redis servers connected to the internet have been discovered by Censys researchers to be targeted by an unknown attacker to facilitate cryptocurrency miner deployment, The Hacker News reports. "The general idea behind this exploitation technique is to configure Redis to write its file-based database to a directory containing some method to authorize a user (like adding a key to '.ssh/authorized_keys'), or start a process (like adding a script to '/etc/cron.d')," said Censys. While there has been no evidence indicating successful compromise of all hosts, Censys discovered that attackers sought to store malicious crontab entries in the "/var/spool/cron/root" file to facilitate shell script execution. The finding showed that China, the U.S., Germany, Singapore, and India had the most exposed and unauthenticated Redis services, while China and the U.S. had the most amount of exposed data. "Israel is one of the only regions where the number of misconfigured Redis servers outnumber the properly configured ones," said Censys.