Debug build of Jigsaw Ransomware contains SMTP email credentials


The SonicWall Capture Labs Threat Research Team observed reports of a new version of the Jigsaw ransomware.  The version analysed here appears to be an early debug build and sports a new interface, a significant departure from interfaces using clown images in previous versions.  As this is a test version of the malware, no encryption actually takes place.

Infection Cycle:

The malware exeutable file contains the following metadata:

Upon execution it displays the following messagebox:

It brings up the following dialog:


The “View encrypted files” button brings up the following page:


The following files are added to the system:

  • %APPDATA%\SkinSoft\VisualStyler\2.4.59444.6\x86\ssapihook.dll
  • {run location}\EncryptedFileList.txt
  • {run location}\FileSystemSimulation\NotTxtTest.nottxt
  • {run location}\FileSystemSimulation\TxtTest.txt.die (empty file)
  • {run location}\Newtonsoft.Json.dll
  • {run location}\SkinSoft.VisualStyler.dll


NotTxtTest.nottxt contains the following text:

I am NOT a txt test.


EncryptedFileList.txt contains the following text:

{run location}\FileSystemSimulation\TxtTest.txt


Nothing is actually encrypted on the system.  Presumably, this is because it is a debug version.


The malware executable file contains the following string:

  • C:\Users\Moises\Desktop\jigsawransomware2019-master\JigsawRansomware\obj\Debug\JigsawRansomware.pdb


The malware makes the following DNS requests:



The following network traffic was observed between the malware and the hosts listed above:


A further look into the executable file reveals credentials for 1455 SMTP email accounts:


The BTC address (3DCMs9XgBi6HDigyPggqhrpMYuwp3d81rM) has some transaction history.  However, it is not certain whether or not the transactions are directly related to ransom payments:


SonicWall Capture Labs provides protection against this threat via the following signature:

  • GAV: Jigsaw.RSM_26 (Trojan)

This threat is also detected by SonicWALL Capture ATP w/RTDMI and the Capture Client endpoint solutions.

Security News
The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.