According to a Check Point Research finding, a new malware package designed to mine cryptocurrency is attacking web servers in an effort to infect them. The malware uses a variation of an open-source Monero miner (XMRig), possibly because the software required does not require an extremely powerful server to operate. According to the article, the attack uses vulnerabilities from 2012 and 2013. Systems targeted included those running PHP, Ruby on Rails, and Microsoft IIS. The vulnerability in Ruby on Rails is CVE-2013-0156. This vulnerability provides the attacker a means to inject objects into the system that can execute arbitrary code. The malware flushes the crontab (on a Unix system) and then installs its own crontab entry. This entry runs one minute past the hour, every hour. The command downloads a robots.txt file from a web server under the control of the attackers. This downloaded file is then executed each time crontab executes the command. The article postulates this could be so that the attackers could execute a kill switch if desired or possibly to update the malware. The open-source package XMRig normally donates five percent of the earnings to XMRig’s author. Apparently, the individual(s) behind this attack were not inclined to lose any potential gains and removed the donating code from the version used in the infection.
Indicators of Compromise:
It is recommended to patch the operating system,patch the applications and check crontab for unusual entry.