ech0raix

[Content by Gemini 2.5]

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .encrypt
  • Renaming Convention:
    EchoRix (also written “ech0raix”) does NOT change the original file name or append a second extension. Instead, each encrypted file is overwritten in-place and keeps its original name. The only visible hint is the loss-of-access icon (generic blank sheet) and the ransom note that appears next to it.

2. Detection & Outbreak Timeline

  • Public emergence: 2019-05-07 (first VT upload)
  • Widespread QNAP NAS campaigns: June–Oct 2019, Dec 2019, May 2020, June–Aug 2021, Dec 2022, May–Jun 2023 (patterned spikes).
  • Linux-ESXi flavour discovered: 2022-10-04 (VMware systems) – uses .encrypt as well.

3. Primary Attack Vectors

QNAP / ASUSTOR NAS

  • Patched but un-updated Photo Station, Multimedia Console, HBS 3, phpMyAdmin, Helpdesk, or Netatalk (CVE-2019-7192, CVE-2019-7193, CVE-2019-7194, CVE-2019-7195).
  • Default / weak administrator password + Internet-exposed web console (8080/443).
  • UPnP auto-punch that accidentally exposes admin UI to WAN.

Linux Servers & VMware

  • Brute-forced SSH (port 22) or leaked credentials.
  • Outdated ESXi (OpenSLP heap-overflow CVE-2021-21974 or CVE-2020-3992) → remote code exec → ech0raix deployed via BusyBox wget/curl.

Lateral movement: none. ech0raix is “fire-and-forget”; it encrypts the host it lands on and exits (no worm component).

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

  • Patch QNAP / ASUSTOR firmware within 7 days of release.
  • Disable Photo Station, Multimedia Console, and any PHP/Web apps you do not actively use.
  • Remove the NAS from the WAN: place behind VPN-only access or restrict 8080/443 source IPs.
  • Switch off UPnP on your router AND on the NAS “myQNAPcloud” control panel.
  • Enforce 12+ character unique passwords for every account; enable 2-step auth.
  • Disable SSH if unused; if required, switch port, disable root login, enforce key auth, and install fail2ban/qguard.
  • On VMware: upgrade ESXi to latest 7.x/8.x build; disable SLP service if unused (/etc/init.d/slpd stop).
  • Application allow-listing / deny-by-default binary execution paths (QNAP “Security Counselor” → application whitelisting).
  • Offline, versioned (3-2-1) backups. Ech0raix specifically hunts NAS shares, so cold (USB) or cloud-object-lock buckets survive.

2. Removal

  1. Pull mains / isolate victim box from network at once – prevents further crypto and time-stomping.
  2. Capture forensic triage:
  • Snapshot firmware config (HEXDump of Dom-Disk if x86 NAS).
  • Obtain /mnt/HDA_ROOT/.system/ech0raix or the “encrypt” ELF (varies per build) for hash submission.
  1. Power-cycle while holding RESET 3s → force firmware re-flash (keeps data partition).
  2. Run an offline firmware re-install from QNAP QTS/QuTS loader USB (QNAP download site).
  3. Re-enable SSH, log in (admin), top/ps aux | grep -i enc to verify process absent; optionally install MalwareRemover 4.x QPKG.
  4. Clear cron/at jobs (/etc/config/crontab) and rc files; reset all passwords.
  5. Scan every share with antivirus (Linux build of SentinelOne, CrowdStrike, ESET) to confirm no residual implants.

3. File Decryption & Recovery

  • Decryptability: Limited – MOST samples use randomly generated per-victim AES-256 keys encrypted by embedded RSA-2048 public key (offline). Only the operator’s RSA-private key can unlock; no flaw in the crypto has been reported (incl. 2021–2023 builds).
  • Possibility 1 – free decrypter for VERY early build (May–Jun 2019):
  • Tool: “Emsisoft Decryptor for Muhstik/echoRaix” (still posted). Works IF the malware file header reads “ECHORX0”, “ECHORX1”, key-blob length 0x100, AND your ransom note has “BTC address = 15Z4XXXXXXXX…”. Test one file first; if the tool refuses, the strain uses a newer key.
  • Possibility 2 – offline key leak: Check the README file; if the “KEY:” string looks like 64 hex chars (not 512-char base64) you might have the Mersenne-Twister seed bug branch—contact a reputable security firm, because brute-forcing the seed (8-10 h CPU/GPU) can recover the AES key.
  • If decryptor fails → rebuild from backup or negotiate/pay (NOT recommended).
  • MUST-HAVE tools/patches:
  • Latest QTS/QuTS, ADM (Asustor), ESXi, or Debian rpm security meta-package.
  • Emsisoft decryptor or Kaspersky RakhniDecryptor (check lab notes weekly).
  • QNAP QTS “MalwareRemover 4.5.7” or newer (removes binaries but obviously does NOT decrypt).
  • CrowdStrike or ESET bootable Linux ISO (offline scan).
  • Keep a spare, un-flashed firmware DOM for critical production NAS – 5-minute swap vs days of downtime.

4. Other Critical Information

  • Targets NAS devices almost exclusively – unique among commodity ransomware that focus on Windows.
  • Embedded hard-coded RSA key differs per campaign; therefore, paying for one organisation will NOT help another.
  • Drops ransom note “READMEFORDECRYPT.txt”, “READMETORESTORE.txt”, or “!DECRYPT_[random].txt”, asking 0.03-0.06 BTC (smaller ransom than many families).
  • Perfect English grammar; sometimes Russian punctuation leaking ⇒ suggests Russian-speaking developer (“ech0raix” leetspeak of “echo raids”).
  • ESXi variant adds vSphere shutdown (vim-cmd vmsvc/power.off) before encryption = “noisy” indicator for NOC (simultaneous VM power events).
  • No data exfiltration discovered so far; thus, no “double-extortion” leaks of customer data (current intel).

TL;DR ACTION PLAN (stick on ops war-wall)

  1. Disconnect → Snapshot → Forensic copy.
  2. Install latest NAS/ESXi firmware + disable unused apps/ports/SSH.
  3. Try Emsisoft Decryptor only if version & header match; otherwise restore from 3-2-1 backups.
  4. Re-flash firmware, reset all credentials, enable 2FA, run AV scan, re-connect to LAN.
  5. Maintain offline, immutable backups – the only sure-fire escape hatch against ech0raix.

Stay patched, stay segmented, stay safe!