cryptorbit

[Content by Gemini 2.5]

# Cryptorbit (CryptoDefense / CryptoLocker 2.1) – Comprehensive Response Guide

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    Cryptorbit appends the .cryptorbit extension to every encrypted file.

  • Renaming Convention:
    Original: Quarterly_Report.xlsx → Encrypted: Quarterly_Report.xlsx.cryptorbit
    No other prefixes, base-64 tags, or random IDs are added; the malware keeps the entire original filename intact and simply tacks on the .cryptorbit suffix.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Active campaigns were first observed mid-March 2014. Spikes continued through June 2014, after which larger families (CryptoWall, later Locky) began to overshadow it. However, dormant or derivative samples still show up in niche malspam campaigns as late as Q1 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Malicious e-mail attachments – ZIP archives containing double-extension files (Invoice.pdf.exe) or Office docs with malicious VBA macros launching the downloader.
  2. Exploit Kit redirects – Angler & Nuclear EK served the payload via outdated Java, Flash, and Silverlight.
  3. Compromised RDP / SMB brute force – Later re-packaged versions used weak or leaked credentials to deploy manually inside networks.
  4. EternalBlue (MS17-010) – Not the original wave, but certain rebundles dropped in 2017-2018 coupled the Cryptorbit core with the EternalBlue exploit for lateral propagation.
  5. Software supply-chain poison – Niche cases where trusted freeware sites were breached to host the trojanized installer.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Patch everything: Apply Microsoft Security Bulletins MS14-068 (Kerberos), MS15-011/MS15-014 (SMB), and MS17-010 (EternalBlue) immediately.
    • Disable SMB v1 across all Windows versions via:
    Disable-WindowsOptionalFeature -Online -FeatureName "SMB1Protocol"
    • Harden RDP: Use account lockout, Network-Level Authentication (NLA), MFA, and only allow access through VPN or jump hosts.
    • Mail & Web filtering: Block executables inside ZIPs and disable Office macro auto-execution unless signed.
    • Least-privilege + Application whitelisting (AppLocker / WDAC).
    • Offline and cloud backups that are not continuously mounted (3-2-1 rule).

2. Removal

  • Infection Cleanup:
  1. Physically isolate (pull network cable or disable Wi-Fi) the affected system to stop further encryption or lateral spread.
  2. Boot a clean recovery OS (Windows PE, Live Linux USB) to avoid the malware’s persistence hooks.
  3. Locate and delete the following executables / batch artifacts:
    • %APPDATA%\Roaming\Microsoft\<random>\<random>.exe
    • %TEMP%\wpbt0.dll (used to hijack the Winlogon Notification Package)
    • C:\ProgramData\Microsoft\Crypto\RSA\*.key (if generated by the trojan)
  4. Using a reputable AV engine (ideally one from a fresh rescue disk) run a full system scan to ensure remnants are gone. Safe-mode scans may no longer be necessary if you booted from an external OS.

3. File Decryption & Recovery

  • Recovery Feasibility:
    YES – Cryptorbit suffers from a flawed key-storage routine (private key left in %APPDATA%\key.dat with insufficient entropy). This flaw yielded the original CryptoDefense Decryptor published by ESET & Fabian Wosar in April 2014, and a maintained fork now also covers .cryptorbit files.
  • Essential Tools:
    • ESET Cryptorbit Decryptor (now ESETCryDecrypt) – GUI or CLI:
    esetdec.exe --input "C:\Users\%USERNAME%\Documents" --key %APPDATA%\key.dat
    • DecryptCryptorbit.zip – community edition by MalwareBytes Labs (Keeps key search automated).
    • If backup copies of key.dat were wiped, brute-force is infeasible—restore from offline backup instead.
  • Post-Operation Validation: Always verify checksums of recovered files against any pre-infection archive.

4. Other Critical Information

  • Additional Precautions:
    • Cryptorbit spawns two hidden processes: Winlogon.exe (ghost copy) and conhost.exe with parent ID = 1. Kill these before attempting decryption.
    • It uses Alternate Data Streams (ADS) Zone.Identifier:$DATA on every encrypted file to mark it already processed—some AV engines miss this when you restore from backup.
    • Registry keys HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\NoDrives = 0x3FFFFFFF may be set to hide logical drives after encryption; reset this once cleanup is complete.
  • Broader Impact:
    Early estimates from ShadowServer, Microsoft, and ViaForensics attribute ≈ 1.2 million infections globally in the first 6 months; damages in excess of USD 32 million were reported (ransom notes demanded 0.5 – 1.0 BTC). The campaign taught blue teams to harden backups, accelerate MSFT patching cycles, and prioritize cloud-mirror solutions—tactics that later blunted larger wormable ransomware waves (WannaCry, NotPetya).