Plink.exe is a tool from the Putty-Tool suite that the Change Auditor agent uses and it is part of the agent installation files to facilitate remote connections to devices such as EMC or NetApp when these types of auditing configurations are used. If this application is being flagged as malware or a threat, this could be considered a false positive and whitelisted, or you could delete it if you do not have these devices or use these types of templates. However, the next time you upgrade or reinstall the agents it will show again.