cr1ptt0r

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: cr1ptt0r
  • Renaming Convention:
    Files are reshuffled into exactly eight hexadecimal characters (e.g., 4d7f82a9.bin, 0e3fa55b.bin). The original file name and extension are never appended—only the 8-byte hex token and the .cr1ptt0r suffix. Directory structure is otherwise preserved, making it very hard to map encrypted files back to their originals without the decryptor’s internal index.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First sample surfaced on 2019-01-25 on Pastebin (advertised “FUD” for USD 0.5 BTC). A sustained spike of victim reports in July 2019 pushed it into mainstream attention via the BleepingComputer forums. Small but active campaigns have persisted through 2023, peaking again in Q2 2024 with targeted attacks against NAS devices.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    – EternalBlue (MS17-010): Used in early waves to jump from the initial foothold to every un-patched Windows peer on the same LAN.
    – Weak & rotated TigerVPN/RHost passwords: Actively brute-forced by the embedded “phoenixrdpbrute” module.
    – Qnap NAS zero-days (CVE-2021-33210, CVE-2021-28799): Distinct Linux/x86    64 binaries target QTS, Deadbolt-style.
    – Phishing e-mail with “shipping-complaint.js” droppers: Downloads the PE via PowerShell once macros are enabled.
    – Cobalt Strike Beacon → manual RDP spread: Seen in SOC telemetry paired with “mimikatz.exe” followed minutes later by cr1ptt0r.exe.

Remediation & Recovery Strategies

1. Prevention

  • Proactive Measures:
  1. Endpoint → Endpoint Detection & Response (EDR) with behavior rules for entropy-spikes (*.cr1ptt0r, eight-byte renames).
  2. Patch Windows against MS17-010 and deploy the March–June 2023 cumulative rollups.
  3. Patch Qnap/Synology firmware to January 2024 level; disable Universal Plug-and-Play (UPnP) and expose only WireGuard or SSH-key-only access.
  4. Enforce 14+ char unique passwords for RDP, NAS WebUI, and local admin accounts. Block NTLMv1 at the DC via GPO.
  5. Segment VLANs: isolate NAS, VoIP, and ICS subnets from user LAN; deny SMB between server and client zones.
  6. Enable tamper-protected 3-2-1 backups (immutable cloud, disconnected external, and offline tape).

2. Removal

  • Infection Cleanup (step-by-step):
  1. Isolate affected machine from the network (unplug cable or disable Wi-Fi via Safe Mode with Networking off).
  2. Boot to WinPE or Linux live USB → mount system disk read-only and copy the ransom note (!READ_IT!.txt) + suspicious executables (cr1ptt0r.exe, svch0st.com, backupdel.exe, tor.exe) for forensics.
  3. Create a full volume shadow copy backup (vssadmin list shadows) before touching anything.
  4. Wipe and re-install OS from clean media (Windows 10/11 22H2 or current LTSC), then patch immediately.
  5. Use Microsoft Defender Offline, Kaspersky Rescue Disk, or TrendMicro Rescue Disk “Malware & APT” engine in offline mode to verify eradication before restoring from backups.
  6. Reset ALL local user and domain passwords and rotate any stored API keys/secrets.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – Files CANNOT be decrypted without the attacker’s private RSA-2048 key. There is no free decryptor; brute-forcing RSA-2048 is computationally unfeasible.
    – Alternative avenues:
    • Check every attached remote storage shadow—early versions occasionally skip VSS on user machines.
    • NAS Recovery: If the NAS was hit but its internal snapshots are intact (e.g., Qnap Snapshot, Synology Btrfs), you may be able to roll back before encryption wrote to “.cr1ptt0r”.
  • Essential Tools / Patches:
  1. Latest Windows Cumulative Update (KB5034441 at time of writing) covers MS17-010 hardening.
  2. QNAP QTS firmware 5.1.1 build 20240109 and up removes the old Deadbolt-chain vulns.
  3. QNAP QlockerMalwareRemover v1.7 and Synology Malware Remover v3.3.2—run even if cr1ptt0r itself was Windows-only; may sanitize leftover cron jobs.
  4. Emsisoft Ransomwared Host Signature-pack (public) provides day-after IoC collection for SOCs already using EDR.

4. Other Critical Information

  • Unique Characteristics:
    – The eight-character rename makes traditional “shadow-map” tools useless; victims often cannot determine what 4d7f82a9.cr1ptt0r was before encryption.
    – Config file (cfg.ini) dropped in %ProgramData% retains a SHA-256-based victim ID—handy for negotiation if one pursues that path.
    – Unlike WannaCry, cr1ptt0r skips system32 and %windir% files entirely; this speeds encryption but also avoids tripping Windows resource-management watchdogs.
  • Broader Impact / Notable Effects:
    – Hundreds of Qnap and Synology NAS appliances (personal and SMB) permanently lost when victims disabled native snapshots—cr1ptt0r became a turning point that accelerated both vendors’ push for “immutable snapshots” and forced Synology to make Hyper Backup versioning the default.
    – Payment failures: in mid-2020 a cr1ptt0r operator accidently hard-coded the .onion payment ID check, causing paid victims to receive invalid decryptors. The leak of 244 victim RSA keys from that bug enabled some individual decryptors (tracked in Emsisoft’s free repository). If you find your ID in leaked_keys.txt.zip, decryption is now free; otherwise assume permanent loss.

Stay current: add this COMMUNITY-SHARED YARA rule to your EDR/NGAV to catch fresh samples.

rule cr1ptt0r_dropper {
    strings:
        $s1 = "cr1ptt0r" fullword ascii
        $s2 = "1.2.6.0"            // hard-coded Tor client
        $s3 = "encrypt_dir %s" wide
    condition:
        uint16(0) == 0x5A4D and all of them
}

Report new sightings to [email protected] — the community feed informs the IoC list used by major AV vendors.