The CIS Controls advocate "a defense-in-depth model to help prevent and detect malware".[21] A May 2017 study showed that "on average, organizations fail 55% of compliance checks established by the Center for Internet Security", with more than half of these violations being high severity issues.[22] In March 2015, CIS launched CIS Hardened Images for Amazon Web Services, in response to "a growing concern surrounding the data safety of information housed on virtual servers in the cloud".[23] The resources were made available as Amazon Machine Images, for six "CIS benchmarks-hardened systems", including Microsoft Windows, Linux and Ubuntu, with additional images and cloud providers added later.[23] CIS released Companion Guides to CIS Controls, recommendations for actions to counter cybersecurity attacks, with new guides having been released in October and December 2015.[24] In April 2018, CIS launched an information security risk assessment method for to implement CIS Controls, called CIS RAM which is based upon the risk assessment standard by the DoCRA Council.[25]