JS/Nemucod.8511!tr.dldr

Analysis

JS/Nemucod.8511!tr.dldr is a generic detection for a type of JavaScript downloader trojan that downloads and runs the Locky ransomware onto the compromised computer. Since this is a generic detection, files that are detected as JS/Nemucod.8511!tr.dldr may have varying behavior.
Below are examples of some of these behavior:

• It downloads the Locky ransomware as the following file:
  
  • undefinedTempundefined\jsxudshmr2.exe : This file is detected as W32/GenKryptik.APXF!tr.


• It adds the ".lukitus" extension to encrypted files.


• It attempts to connect to the following URL:
  
  • hxxp://ani{Removed}.net/jbYUF6D

Recommended Action

• Make sure that your FortiGate/FortiClient system is using the latest AV database.
• Quarantine/delete files that are detected and replace infected files with clean backup copies.