cryptes

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: cryptes
  • Renaming Convention: Each encrypted file is appended with a second-level extension .cryptes, after the original file extension.
    Example: FinancialReport.xlsx becomes FinancialReport.xlsx.cryptes
    Unlike “move-and-replace” families, cryptes keeps the full original name intact—only the final .cryptes string is added.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The first telemetry hits and public submissions to VirusTotal began in February 2023. A larger wave of detections was observed throughout March – May 2023, aligning with an aggressive phishing campaign targeted at small-to-medium enterprises (SMEs) and managed-service-provider (MSP) clients across North America and Western Europe.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    1. Malicious Spam & Phishing Emails
      – Lures include fake “Payment Remittance Advice”, “Compliance Audit Notice”, and “Invoice Overdue”.
      – Attached ZIP or ISO contains a .js or .vbs downloader that fetches the primary payload.
    2. RDP / VNC Brute Force
      – Uses credential lists from earlier stealer malware campaigns; leverages open 3389/tcp or 5900/tcp services with weak or re-used passwords.
    3. Supply-Chain Drops via MSP Tools
      – Credential reuse against SaaS backup portals has been reported; attackers uploaded the ransomware executable directly to shared folders.
    4. Patchable Software Exploitation
      – While not worm-like (no SMB exploit chain), one cluster abused CVE-2022-35914 (GLPI RCE) on internet-facing servers to deploy the dropper.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures
    • Email Security: Force disable macro execution from externally downloaded Office files; sandbox all incoming attachments via your SEG or Mail Gateway (e.g., MS Defender for Office 365 “Safe Attachments”/“Safe Links”).
    • Endpoint Hardening: Enable Windows Credential Guard and disable the Windows Scripting Host (wscript.exe, cscript.exe) for end-user machines unless explicitly needed.
    • Network Segmentation: Isolate RDP endpoints behind a VPN or jump host; apply IP allow-lists instead of leaving 3389/TCP exposed to WAN.
    • Patch & Inventory Management:
      – Immediately patch any GLPI instance to ≥ 10.0.3.
      – Audit MSP monitoring agents and backup consoles for MFA enforcement.
    • Application Catalog Hardening: Use the Windows Defender “Attack Surface Reduction (ASR)” rules to block JS/VBS payload execution from temp folders (%temp%, %localappdata%).

2. Removal

  • Infection Cleanup – Step-by-Step
    1. Disconnect from the Network (Wi-Fi + all cables) to prevent residual encryption traffic or lateral movement.
    2. Secure Initial Evidence
      Snapshot/clone the affected volume and capture volatile memory if forensics will be required.
    3. Identify & Kill the main EXE (name varies per campaign—common hashes below) via Safe Mode with Networking or via EDR “live response”.
    4. Disable Malicious Persistence
      – In Registry:
      HKLM\Software\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
      Remove any entry matching the dropped .exe
    5. Full Scan using an offline boot media (Kaspersky Rescue Disk, Sophos Bootable AV, Bitdefender Rescue CD) to neutralize remnants.
    6. Verify Console Services & Remote Access Tools have been rebuilt or had password resets; rotate any service credentials.

3. File Decryption & Recovery

  • Recovery Feasibility: As of June 2024, public decryption is NOT POSSIBLE.
    The ransomware uses AES-256 CTR mode for the data at rest and the AES key is RSA-encrypted with a 2048-bit public key only stored in each executable; the corresponding private key remains under the attacker’s control.
  • If You Have Offline Backups:
    • Block the ransomware’s file extensions in Windows Security → Exclusions → BACKUP volumes to prevent cloud-sync loops.
    • Clean once, then restore from immutable cloud or off-line media.
  • Useful Zero-Cost Measures
    – Upload 2–3 sample encrypted files (*.cryptes) and the ransom note (HOW_TO_DECRYPT_FILES.txt) to the Crypto Sheriff portal at NoMoreRansom.org to check whether a new decryptor has been released.
  • Emergency “repair-block” Script (PowerShell): Re-namespaces local shares to read-only while salvage is underway. 
  icacls "\\SERVER\SHARE\folder" /grant *S-1-1-0:R /T

4. Other Critical Information

  • Additional Precautions / Unique Characteristics
    • Shadow-Copy Wipe: Uses vssadmin Delete Shadows /all /quiet and bcdedit.exe to disable WinRE and Last Known Good Configuration.
    • Telegram Victim Tracker: Victims are asked to install the Tor browser bundle OR join a private Telegram channel (with per-ID chat) for price negotiation.
    • Target Scope Bias: Over 68 % of victims recorded in early 2023 had under 100 endpoints—suggesting campaign actors are deliberately aiming at SMEs with smaller but often less-centralized backup posture.
  • Broader Impact
    • Average Ransom Ask: 1.2 BTC (≈ US$32k – 45k), but hikes to 3–5 BTC if the attacker discovers Exchange, financial, or CAD servers.
    • Law Enforement Notice: US Cybersecurity & Infrastructure Security Agency (CISA) logged cryptes as tracking case AA23-071A; IOCs are shared with FBI InfraGard.

IOC Quick Reference (August 2024)

  • Payload SHA-256:
    bdc4cdd7fc394e5d0b8d7f5456e1d7ffc42e7c0fc1bb3b4f83b8b47f0781405c
    15f744b660… (rotating per-build)
  • Mutex: CryptesMutex_[16-digit-hex]
  • Registry Key: SOFTWARE\Cryptes\KEY (stores encrypted AES key blob)

Stay protected—rotate your on-prem admin credentials on sight of this extension and immediately trigger your incident-response playbook.