CryptoWall 4.0 Released with a New Look and Several New Features

November 4, 2015  By Pierluigi Paganini


The fourth member of the CryptoWall family of ransomware, CryptoWall 4.0, has just been released, complete with new features and a brand new look.

We recently reported that CryptoWall 3.0 has allegedly caused over $325 million in annual damages. CryptoWall first emerged in April 2014. Its first major upgrade was dubbed CryptoWall 2.0, and first emerged in October 2014. CryptoWall 3.0 then emerged in January 2015 and terrorized organizations on a global scale. Now, in November 2015, CryptoWall 4.0 has emerged.

New Features

New features such as the encryption of the names and extensions of affected files have emerged with the 4th member of the CryptoWall family. Additionally, CryptoWall 4.0 has changed the name of its ransom notes to HELP_YOUR_FILES.TXTand HELP_YOUR_FILES.HTML.

The ransom note itself contains payment instructions and also mocks the infected user.

CryptoWall 4.0

Spread Method

The initially reported sample, provided by an infected user on the Bleeping Computer forums, was spread via e-mail through phishing e-mails with ZIP archive attachments claiming to be resumes. The file within the ZIP archive is a JavaScript file, that is obfuscated and beautified that downloads the CryptoWall 4.0 payload from a hard-coded URL.

CryptoWall 4.0 2

However, it’s likely that exploit kits will begin to deliver CW4 as a payload very soon, if they are not already (especially the Angler EK).

Technical Information

The C&C communication and behavioural activity of CryptoWall 4.0’s payload is quite similar to its earlier versions. The specific sample that I have analyzed performed the following actions, as can be evidenced by the below images.

Contacted Domains

CryptoWall 4.0 3 CryptoWall 4.0 4

Added Files

CryptoWall 4.0 5

Deleted Files

CryptoWall 4.0 6

Modified Files

CryptoWall 4.0 7

Added Registry Keys

CryptoWall 4.0 8

Process Tree

  • INITIAL SAMPLE
    • exe
      • exe -k netsvcs
        • EXE “C:UsersAdministratorDesktopHELP_YOUR_FILES.TXT”
        • exe “C:UsersAdministratorDesktopHELP_YOUR_FILES.HTML”
      • exe Delete Shadows /All /Quiet

 

About the Author Michael Fratello

Michael Fratello is a Senior Security Engineer employed by CipherTechs, Inc., a privately held information security services provider located in downtown Manhattan, New York.  Specializing in Penetration Testing and Digital Forensics, Michael, a St. John’s University graduate majoring in Computer Security Systems, has developed a passion for information security and often spends his free time studying, programming, and researching the exponentially growing number of threats found in-the-wild today.

Edited by Pierluigi Paganini

(Security Affairs –  CryptoWall 4.0, ransomware)



Pierluigi Paganini
Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.





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