Lazarus APT Hackers Attack Japanese Organization Using Remote SMB Tool “SMBMAP” After Network Intrusion

by chebbi abir

Researchers from JPCERT/CC observed that the world’s most dangerous APT hackers attack Japanese organization with different malware for during and after the intrusion on the targeted network.

Lazarus is also known as Hidden Cobra is a North Korean APT hacker group that has been involved with various high profile cyber-attacks various government and private sectors around the globe since 2009.


Lazarus hacker group believed to be working under the North Korean state-sponsored hacking organization Reconnaissance General Bureau and using various attack methods such as Zerodays, spearphishing, malware, disinformation, backdoors, droppers.

Attackers using the obfuscated malware for the ongoing attack against Japanese organizations with some of the sophistication functionalities to gain access to the network for the various malicious activities.

One of the Malware Infection Process

The initial stage of the infection starts with download and executes the configuration modules and stored in the specific folder C:¥Windows¥System32¥.

Attackers added some unnecessary files and bundled it as ZIP which contains more than 150 MB data, and the file is obfuscated used VMProtect.

The initial configuration file of the malware is completely encrypted, later it is stored in the registry entry and loaded automatically when the malware gets executed.

Here the complete malware behavior, configuration, communication format and modules.

APT Malware behavior

Attackers encrypted all the Strings in the Malware with AES128 and hardcoded the Encryption key.

According to the JPCERT/CC Report “Since the malware converts the 16-letter string to wide character (32 bytes), only the first 16 bytes is used as a key.”

“Windows API name is also AES-encrypted. After decrypting API strings, the address for the APIs that are called by LoadLibrary and GetProcAddress are resolved.”


After the successful infection malware, send the HTTP request to C2 server with the following information:-

Later the malware focus to downloading a module from the C2 server through various communication attempt. once it is successfully downloaded, it requests the command from the C2 server where the attackers send the specific commands.

Download the module will be having the various functionality of the following:-

  • Operation on files (create a list, delete, copy, modify time created)
  • Operation on processes (create a list, execute, kill)
  • Upload/download files
  • Create and upload a ZIP file of arbitrary directory
  • Execute arbitrary shell command
  • Obtain disk information
  • Modify system time

Finally, attackers spread the infection and leveraging account information with help of the Python tool “SMBMAP” which allows access to the remote host via SMB after converting it as a Windows PE file with Pyinstaller.


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