Issue
Praying Mantis attacks are a type of malware or vulnerability. It is malware based around IIS servers through a number of different vulnerabilities. One set of vulnerabilities they are targeting has to do with the Telerik Library which K2 uses.
Resolution
There are other vulnerabilities which these "praying mantis" attacks target in the IIS application but the K2 Development team has worked diligently to make use of security protocols to avoid these vulnerabilities. One such vulnerability that was patched out of K2 is found in the following KB article. To ensure the most security, it is recommended to stay up to date on all fix packs and versions of K2.