A Tweet posted recently by AVG researcher, Jakub Kroustek, suggested that a new ransomware, written entirely in Python, had been found in the wild, joining the emerging trend for Pysomwares such as the latest HolyCrypt, Fs0ciety Locker and others.
This Python executable comprises two main files. One is called boot_common.py and the other encryptor.py. The first is responsible for error-logging on Windows platforms, while the second, the encryptor, is the actual locker. Within the encryptor are a number of functions including two calls to the C&C server. The C&C is hidden behind a compromised web server located in Israel. The Israeli server was compromised using a known vulnerability in a content management system called Magento, which allowed the threat actors to upload a PHP shell script as well as additional files that assist them in streaming data from the ransomware to the C&C and back.
A notable point to mention is that the server was also used for phishing attacks, and contained Paypal phishing pages. There are strong indications that a Hebrew-speaking threat actor was behind these phishing attacks. The stolen Paypal credentials were forwarded to another remote server located in Mexico and which contains the same arbitrary file upload technique, only with a different content management.
It is a known practice for attackers to look for low-hanging fruit into which they can inject their code in order to hide their C&C server. One such example was the CTB-Locker for web servers reported last March.