AhnLab Security Intelligence Center discovered ransomware disguised as a password cracker tool that encrypts files using AES-256 in CFB mode, making data recovery impossible even after ransom payment. This ransomware tricks users into running it by mimicking legitimate hacking tools, increasing the risk of infection. #AhnLab #PyInstaller #AES256CFB #snapReadme #ransomwaredisguise
Keypoints
- Ransomware is disguised as a password cracker tool to trick users into running it.
- Created with PyInstaller, the ransomware prompts users for a username and email to appear legitimate.
- It encrypts files using the AES-256 algorithm in CFB mode without storing or transmitting keys, preventing file recovery.
- Encrypted files receive a “.NS1419” extension and original files are deleted after encryption.
- The ransom note named “snapReadme.txt” demands Bitcoin payment but decrypting files is practically impossible.
- File encryption excludes directories containing “Program Files” or “Windows” and the ransom note itself.
- Users are advised to avoid downloading tools from unreliable sources and to use official or trusted websites.
MITRE Techniques
- [T1059] Command and Scripting Interpreter – The ransomware is executed through a Python program converted to an executable with PyInstaller, displaying terminal output to disguise its activity (‘the fake cracker displays a message in the terminal output window’).
- [T1047] Windows Management Instrumentation – The ransomware requests “Run as Admin” privileges to execute commands under elevated permissions (‘selects “Run as Admin” and clicks “START HACK (Admin Only)”)
- [T1486] Data Encrypted for Impact – Uses AES-256 encryption in CFB mode to encrypt victim files and add the extension “.NS1419” (‘The file encryption method is the AES-256 algorithm in CFB mode’).
- [T1530] Data from Information Repositories – The ransomware targets and encrypts multiple file types while excluding specific directories to avoid detection or disruption of system files (‘If the file path contains the string “Program Files” or “Windows”, it is excluded from the encryption’).
- [T1204] User Execution – Relies on victims voluntarily executing the disguised ransomware by presenting it as a password cracker tool (‘ransomware disguised as password cracker’).
Indicators of Compromise
- [File Hash] MD5 hash of the ransomware executable – c925c280d41a19ca4c1e89482b1ee508
- [File Extension] Encrypted file extension added by ransomware – .NS1419
- [File Name] Ransom note file created by ransomware – snapReadme.txt
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