Pierluigi Paganini November 02, 2015

Security researchers of the Cyber Threat Alliance have conducted an investigation into the cybercriminal operations leveraging CryptoWall 3.0 ransomware.

Brief Background

Ransomware, specifically crypto-ransomware, is a malware classification that encompasses Trojans that enumerate the file system of an infected host, in order to discover and compromise any and every document possible. Crypto-ransomware encrypts the contents of supported data files, rendering these files useless to their rightful owner.

This malware classification is quite self-explanatory; ransomware will often drop ransom notes in many areas within the affected file system, in varying formats and/or languages, that demand that the victim pays a ransom in order to recover their files. This ransom is usually paid in Bitcoin, with a (sometimes empty) promise of providing a decryption utility in order to recover all affected files, as a result of a successful, cleared ransom payment.

The CryptoWall family of ransomware first emerged in April 2014. Its first major revision came with the upgrade to CryptoWall 2.0, in October 2014. The most recent variant of the CryptoWall ransomware, CryptoWall 3.0, emerged in-the-wild beginning in January 2015.

The sophistication of CryptoWall 3.0 has skyrocketed exponentially since its initial inception; CryptoWall 3.0 is the most advanced, and the most prevalent ransomware actively distributed in-the-wild today.

Statistical Information

Through a collaborative effort between several large, well-respected information security firms, several CryptoWall 3.0 campaigns were able to analyze with great granularity, revealing a wealth of information behind the threat actor(s) and their effectiveness. The information security firms that participated in this analysis includes: Intel Security, Fortinet, Symantec, Palo Alto Networks, and several other members of the Cyber Threat Alliance.

Monetary Damages: Approximately $325 Million
Analyzed Malware Samples: Over 4,000
Discovered C&C URLs: Approximately 839
Discovered 2nd-Tier C&C IP Addresses: Approximately 5
Total Infection Attempts: Over 400,000 Across 49 CryptoWall 3.0 Campaigns
Region Most Affected: North America

Across 49 analyzed CryptoWall 3.0 campaigns, over 400,000 infection attempts were logged. CryptoWall 3.0 is commonly delivered via phishing e-mail, but it is also quite commonly delivered as a payload of an exploit kit. Specifically, CryptoWall 3.0 seems to be the most commonly delivered payload by the Angler EK; the most active, sophisticated exploit kit found in-the-wild today. CryptoWall 3.0 ransom payments accounted for an estimated total of more than $60 million in revenue for an Angler EK group exposed by Cisco’s Talos Group earlier this year.

Closing

It just goes to show that the prevalence of ransomware in-the-wild is on the uprise, and the exponential growth of ransomware in sophistication and quantity of variants is not slowing down. Malware authors have been leveraging exploit kits to deliver their ransomware; a very effective infection method that is only becoming increasingly hard to defend against.

About the Author Michael Fratello

Pierluigi Paganini

(Security Affairs – CryptoWall  3.0, ransomware)