Hackers exploit Apache Solr instances with cryptocurrency miner

Hackers have attacked over 1,400 Apache Solr servers late last month to install a cryptocurrency miner.

Apache Solr is a popular open source program for building search functionality into websites and is based on a Java library called Lucene.

Researchers say the attack resembles a similar campaign discovered back in January that targeted systems running unpatched Oracle WebLogic software. In that attack, hackers installed a mining rig used to mine Monero cryptocurrency.

In the latest attack, hackers targeted unpatched Apache Solr systems via a critical remote execution vulnerability (CVE-2017-12629), that was since patched by Apache back in October. Also, see Red Hat’s security advisory.

According to SANS security researcher, Renato Marinho, the campaign exploited 1416 vulnerable Apache Solr servers in just 9 days between February 28 to March 8. The attacker used the exploit to install Monero XMRig miners across the globe.

An excerpt of the Solr vulnerability (CVE-2017-12629):

“Remote code execution occurs in Apache Solr before 7.1 with Apache Lucene before 7.1 by exploiting XXE in conjunction with use of a Config API add-listener command to reach the RunExecutableListener class. Elasticsearch, although it uses Lucene, is NOT vulnerable to this. Note that the XML external entity expansion vulnerability occurs in the XML Query Parser which is available, by default, for any query request with parameters deftype=xmlparser and can be exploited to upload malicious data to the /upload request handler or as Blind XXE using ftp wrapper in order to read arbitrary local files from the Solr server. Note also that the second vulnerability relates to remote code execution using the RunExecutableListener available on all affected versions of Solr.”

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