In January 2016 we published our analysis of a spearphishing attack against energy companies in Ukraine. That attack probably has a connection to the infamous BlackEnergy attacks in 2015 because the attackers used exactly the same mail server to send spearphishing messages. However, the attacks in January 2016 were different. Instead of using the BlackEnergy malware family, the attackers used a relatively simple open-source backdoor, written in the Python programming language, called GCat. The Python code of the GCat backdoor was obfuscated, then converted into a stand-alone executable using the PyInstaller program