Trend Micro Facebook TrendLabs Twitter Malware Blog RSS Feed You Tube - Trend Micro
Search our blog:

  • Recent Posts

  • Calendar

    June 2014
    S M T W T F S
    « May   Jul »
    1234567
    891011121314
    15161718192021
    22232425262728
    2930  
  • About Us
    TrendLabs Security Intelligence Blog(breadcrumbs are unavailable)

    Archive for June 1st, 2014




    We highlighted in our quarterly threat roundup how various ransomware variants and other similar threats like CryptoLocker that now perform additional routines such as using different languages in their warning and stealing funds from cryptocurrency wallets. The addition of  mobile ransomware highlights how these threats are continuously improved over time.

    We recently encountered another variant that used the Windows PowerShell feature in order to encrypt files. This variant is detected as TROJ_POSHCODER.A.  Typically, cybercriminals and threat actors have used Windows Powershell to go undetected on an affected system, making detection and analysis harder. However, once detected, using PowerShell made it easier to analyze as this malware is also hardcoded. Decrypting and analyzing this malware was not too difficult, particularly compared to other ransomware variants.

    Since it uses Powershell, TROJ_POSHCODER.A is script-based, which is not common for ransomware. It uses AES to encrypt the files, and RSA4096 public key cryptography to exchange the AES key. When executed, it adds registry entries, encrypts files, and renames them to {filename}.POSHCODER. It also drops UNLOCKYOURFILES.html into every folder. Once all files on the infected system are encrypted, it displays the following image:

    Figure 1.  Instructions on how users can supposedly retrieve their files

    Once users followed the instructions stated in the ‘ransom note,’ they will see the image below informing them to install the Multibit application that will allow them to have their own Bitcoin-wallet account for 1 Bitcoin. When they purchase the application, they are instructed to submit the form that contains information like email address, and BTC address and ID. Users will supposedly get the decryptor that will help encrypt the files.

    Figure 2. Users need to fill this form once they avail of the Multibit application

    Currently, POSHCODER uses English for its ransom notes and primarily affects users in the United States.

    Ransomware and other similar threats are continuously improving as exemplified by the emergence of POSHCODER.  Trend Micro protects users from this threat via its Smart Protection Network that detects the malicious file.

     
    Posted in Bad Sites, Malware | Comments Off


     

    © Copyright 2013 Trend Micro Inc. All rights reserved. Legal Notice