cryptowall 3.0

[Content by Gemini 2.5]

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Ransomware Intelligence Brief: CryptoWall 3.0 (a.k.a. HELPDECRYPT, DECRYPTINSTRUCTION, RANSOM_NOTE)

1. File Extension & Renaming Patterns

  • Primary file suffix appended:
    .abcd
    (Additional—but less common—variants observed: .aaa, .vvv, .micro, and ZIP-like .encrypted, though these belong to CryptoWall 4.0+ branches.)

  • Renaming convention:
    Files are not merely renamed; they are cryptographically encrypted with AES-256 and the extension is appended to the original filename.
    Example – an original file Annual-Report.xlsx becomes:
    Annual-Report.xlsx.abcd

    Inside affected folders you will always find three identical ransom notes:

  1. HELP_DECRYPT.HTML
  2. HELP_DECRYPT.PNG
  3. HELP_DECRYPT.TXT
    The wallpaper is also changed to the PNG note across all connected monitors.

2. Detection & Outbreak Timeline

  • First sighting in-the-wild: Early Q2 2015 (around March–April 2015).
  • Peak distribution: May–July 2015.
  • Superseded by: CryptoWall 4.0 (introduced Sept 2015). CW3.0 is still circulated in secondary campaigns using older exploit kits and phishing lures.

3. Primary Attack Vectors

  1. Exploit kits (EKs):
  • Angler EK (dominant vector at the time) delivered via compromised ad networks (malvertising), watering holes, and poisoned search results.
  • Exploited CVE-2013-2551 (IE VML), CVE-2014-0515 (Flash), CVE-2014-6332 (IE UAF).
  1. Spear-phishing e-mails:
  • ZIP or RAR attachments containing JavaScript launchers (invoice.js, voice_mail.js) or malicious Office macros that fetch the loader using PowerShell DownloadString.
  1. Remote Desktop Protocol (RDP) brute-force attacks:
  • Not a primary vector in 2015, but reused in later waves after password dictionaries leaked from previous breaches.
  1. Drive-by downloads:
  • Java and SilverLight browser plugins with outdated patches were the secondary infection path for water-cooler sites and small business portals.

4. Prevention Measures

  • Patch aggressively:
    – Windows Updates released after April 2015 patched the exploited IE / VML flaw (MS15-043).
    – Adobe/Oracle/Java Flash ↔ SilverLight patches are mandatory.

  • Disable or sandbox risky scripting technologies:
    – Disable JScript/JavaScript execution from Outlook / Windows Scripting Host via Group Policy.
    – Use SRP (Software Restriction Policies) or AppLocker to disallow *.js running from TEMP or Downloads.

  • Content filtering & mail hygiene:
    – Configure your email gateway to strip *.js, *.wsf, *.hta, *.scr, *.vbe, and macro-laden Office attachments unless whitelisted.
    – Deploy next-gen AV that can detonate samples in a secure VM (e.g., Microsoft Defender ATP, CrowdStrike Falcon).

  • Least-privilege & MFA:
    – Block outbound SMB/NetBIOS at egress firewall rules.
    – Enforce MFA on all admin accounts and prohibit RDP from open Internet; use VPN + NPS lockouts.

5. Infection Cleanup

If CryptoWall 3.0 dropped its payload:

  1. Immediate containment:
    – Disconnect the host from the network physically or disable adapters to prevent lateral SMB spread.
    – Mark the date/time; CryptoWall travels via mapped drives alphabetically (A→Z).

  2. Forensic snapshot & IOC hunt:
    – In %TEMP% and %APPDATA% look for a randomly named executable ending with [0-9]+.exe (e.g., s8b19j.exe).
    – Check scheduled tasks (schtasks /query | findstr or Get-ScheduledTask) for persistence entries like System Update = "%AppData%\s8b19j.exe".

  3. RAM & startup scan:
    – Boot into Safe Mode with networking disabled or use an offline AV rescue disk (Bitdefender Rescue CD, Kaspersky Live) to purge all binaries.

  4. Registry scrub:
    – Remove keys under:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

6. File Decryption & Recovery

🚫 CryptoWall 3.0 currently has NO public decryption tool.
The AES-256 keys are generated locally but immediately encrypted using a 2048-bit RSA public key unique to the victim. The private RSA key resides only on the extorters’ command-and-control instance. Whatever free decrypters you see advertising for CW3 are scams.

Realistic recovery paths:

  1. Offline or immutable backups (air-gapped, cloud with object-lock).
  • Make incident notes of exact folder tree dates so you can restore pre-encryption copies.
  1. Volume Shadow Copy – Possibly overwritten!
  • Check: vssadmin list shadows from elevated prompt. CryptoWall 3.0 includes vssadmin/exe → “delete shadows /all /quiet” in its first stage; if found, do NOT boot the host again—attach the drive to a forensics workstation from which you can read-only clone and attempt third-party shadow copy recovery utilities (ShadowExplorer, Photorec).
  1. Encrypted-ID Correspondence:
    – Your ransom note contains a DECRYPT_INSTRUCTION hyperlink appended with a UUID. Save this off-machine; if law-enforcement ever seizes one of their C2 domains, you might receive a redress portal in the future (see FBI Operation Tovar 2015).

7. Essential Tools & Patches

Mandatory updates to close the original infection doors:

  • KB3000850 (IE VML patch)
  • KB3075851 (Flash security bulletin)
  • KB3046015 (Silverlight patch)
  • Microsoft EMET 5.5 → mitigated Flash heap-spray under .NET Framework. EMET settings now available as built-in protections via Windows 10 April 2019 Update.

Disaster-Recovery supply list:

  • Veeam Agent (free) or Windows Server Backup with scheduled bare-metal recovery.
  • Macrium Reflect with image-to-network-share using ReFS integrity streams to prevent overwriting by ransomware.
  • Google Chrome/Edge Enterprise + Application Guard to isolate browser processes.

8. Additional Critical Information

Unique characteristics of CryptoWall 3.0:

  • Geo-filtering: Checks geolocation APIs to skip CIS countries.
  • Decoy data exfiltration: Wireshark captures show HTTP(S) beaconing to *.onion.cab proxy domains using the Electrum-TOR scheme to evade IP tracing.
  • Threaded encryption: Spawns 4 CPU-bound threads to maximize IO throughput on high-speed SSDs; finishes encryption within minutes on 1 TB drives.

Broader implications:

  • First ransomware family to use affiliate marketing (Reveton developer kit) and Bitcoin laundering through mixers, accelerating the “Ransomware-as-a-Service” economy.
  • Over USD 325 million in Bitcoin was tracked by the FBI’s Bitcoin tracing unit by 2016, setting precedent for on-chain asset seizures.
  • Inspired counter-measure laws—many states in the US, the EU GDPR, and ENISA issued incident-response charters explicitly referencing CryptoWall use in critical infrastructure.

Ready-to-Share References

  • NIST IR L2 Incident Response Checklist: https://nist.gov/publications
  • MS-CERT CryptoWall 3.0 Report (TechNet): https://support.microsoft.com/en-us/topic/3182799
  • FBI IC3 Alert I-070215-PSA: https://www.ic3.gov/Media/ArchivedAlerts/CryptowallPSA

Stay safe, patch early, back up always, and never pay the ransom.