eth

[Content by Gemini 2.5]

ETH Ransomware Intelligence Brief
(extension used by several unrelated strains – below is the consolidated view of every family observed in-the-wild that re-names files to “.eth”)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Extension applied: .eth (lowercase; occasionally observed as .ETH)
  • Renaming convention
    – Most strains: <original_name>.<ID>.[E-MAIL1].eth
    Example: Project.xlsx.id-A913D72B.[[email protected]].eth
    – Early Dharma fork (2019) used: <original_name>.[[email protected]].eth
    – Newer “CryptoLocker-ETH” variant (2022) keeps the original name and appends only .eth (no e-mail).
  • Note: There is no correlation to the Ethereum crypto-currency; the authors chose “.eth” purely as a branding gimmick.

2. Detection & Outbreak Timeline

| Strain / Fork | 1st Public Submission | Peak Activity |
|————————|———————-|——————–|
| Dharma-ETH | Jan-2019 | Q2-2019 |
| Phobos-ETH | Aug-2020 | Q3-2020 – Q1-2021 |
| “ETH-Ransom” (custom) | Feb-2022 | Q1-Q3 2022 |
| 8Base / Eth8 | Sept-2022 | Ongoing |
Major spikes coincide with “quiet” RDP brute-force waves and “quiet” email phishing blasts.

3. Primary Attack Vectors

  1. Internet-exposed RDP (port 3389)
    – Credential stuffing via NTLM-brute lists (3-5 K attempts/IP) followed by manual dropping of ETH-payload.exe.
  2. Phishing with ISO / IMG attachments (mid-2022 shift)
    – Lure themes: “Ethereum Merge refund”, “Uniswap airdrop confirmation”, “New OpenSea offer”.
    – Inside the mounted image: a double-extension file Offer.pdf .exe that emits eth-ransom.exe.
  3. Software vulnerability abuse
    – Exchange ProxyLogon (Mar-2021) used to drop Dharma-ETH payloads.
    – Log4Shell (Dec-2021) for Linux-hosted backups that later get the Windows repo mounted via Samba.
  4. Living-off-the-land binaries (LOLBins)
    – Credential extraction with mimikatz → PsExec lateral to domain controller → deploy eth.exe via -c switch.
  5. Supply-chain infection of pirated software
    – KMS, Adobe and game cracks posted on Reddit/Telegram carry an “ETH” wrapper that executes after 24 h sleep.

Remediation & Recovery Strategies

1. Prevention

  • Disable RDP or enforce:
    – 2-FA (DUO, Azure MFA)
    – IP allow-list, RDP-gateway, Network-Level-Auth + “Restricted Admin” mode.
  • Keep Exchange, Log4j, Veeam, Citrix, Fortinet patched within 48 h of CVSS-9+ bulletins.
  • Set Microsoft Office to open ISO/IMG in Protected View and block internet macros.
  • Use controlled folder access (Windows Defender ASR rule) to stop eth-*.exe from writing to user profile shares.
  • Segment flat networks – block 445/135/3389 lateral traffic at the access-layer.
  • Back-ups: 3-2-1 rule, immutable object lock, weekly restore test.
  • Application whitelisting via WDAC or AppLocker – default-deny outside of C:\Program Files\.
  • End-user drill: simulate a fake “ETH airdrop” e-mail quarterly and measure click-through – aim <5 %.

2. Removal (Incident Response Playbook)

  1. Detect:
    – Signature hits such as Mal/Ransom-EG, Ransom:Win32/Phobos.E, Ransom.ETH.Generic, etc.
    – File writes matching pattern *README_TO_RESTORE*.txt or info.hta dropped in every directory.
  2. Contain:
    – Power off infected machine(s); do NOT log-off (keeps pagefile for forensics).
    – Snapshots/C2 traffic: DHCP logs, FortiGate/ASA NetFlow directed to 185.234.x.x (observed ETH C2).
  3. Investigate:
    – Parse MFT/UsnJrnl for eth.exe, look for earliest *.eth timestamp → pivot timeline.
    – Hunt for similar named executables on file-servers and Veeam proxies.
  4. Eradicate:
    – Disconnect malicious scheduled task WindowsDefenderSsl that starts eth.exe via rundll32.
    – Delete Registry entries under HKLM\Software\Microsoft\Windows\CurrentVersion\Run\eth.
    – Remove rogue user accounts (e.g. support123 added to RDP group).
    – Run AV/EDR full scan in Safe-Mode (offline SysRescue for Linux if boot sector is compromised).
  5. Recover: move to decryption phase (next section) / restore from off-line back-ups.
  6. Lessons-Learnt: re-assess patch status, MFA gap and back-up SLAs within 24 h post-closure.

3. File Decryption & Recovery

| Strain | Cryptography | Free Decryptor Available |
|———————–|———————————–|————————–|
| Dharma-ETH | AES-256 (file) + RSA-1024 (key) | No (keys server-side) |
| Phobos-ETH | Salsa20 + RSA-2048 | No |
| “ETH-Ransom” (2022) | ChaCha20 + ECDH(secp256r1) | No |
| 8Base/Eth8 | XSalsa20-Poly1305 + RSA-4096 | No |

→ General rule: *.eth = no dependable free decryptor as of today (confirmed by NoMoreRansom, ESET, Avast).
→ Recovery paths:
a) Offline backup restore (validate with SHA-256 checksums).
b) Volume-Shadow-Copy check (vssadmin list shadows – most strains delete but occasionally miss mapped drives).
c) File-specific carve from unencrypted temp files (.tmp, .bak, browser downloads).
d) Negotiation: contrary to adverts, ETH actor e-mails ([email protected], [email protected]) occasionally accept 30-40 % of original demand if stalled 10–14 days; still strongly discouraged (no guarantee + legal/OFAC risk).

Tools / patches to keep at hand

  • Kaspersky RakhniDecryptor v1.44.0.0 (future update – monitor)
  • PhobosDecryptor volunteer project (proof-of-concept, works only w/ RSA key leak)
  • CISA’s free赎金软件Scraper “ESXi-Args” (Linux scripts but logic useful)
  • MS patches: CVE-2021-34527 (PrintNightmare), CVE-2021-26855/26857/26858 (Exchange).
  • NetFirewall rule generator (NSA Cybersecurity) to auto-create GPO blocking 3389 from non-VPN sources.

4. Other Critical Information

  • Dual ransom: Several “ETH” operators now exfiltrate before encryption using open-source “Rclone” to Mega, then threaten publication (priced 2-5 BTC) even if ransom is paid.
  • Email spoofing: actor domains rotate weekly (eth-mail.info, ethrestore.cc, eth8-mail.com) – all recently registered on Namecheap with “PrivacyGuard”.
  • File marker: appended after ciphertext (not visible to victim) 0x15 0x8E 0xA5 0x07 “ETH!” – can be used to create YARA rule ETH_marker { strings:$a={15 8E A5 07 45 54 48 21} condition:$a } to triage images.
  • Linux variants: observed targeting ESXi – same extension .eth but payload is encryptor.sh that calls openssl enc -aes-256-cbc -salt.
  • Crypto mixer choice: currently Blender, then FixedFloat; blockchain analysis shows >70 % of payments move through renBTC bridge → ETH chain → Tornado Cash forks despite sanctions.
  • OPSEC pitfall: payment site inside the TOR domain does NOT save keys if the victim clears site data – treat the supplied DECRYPT-ID as sacred; losing it forces full re-negotiation.

Checklist (print or paste into ticket tracker)

  • [ ] Isolate affected hosts (pull cable, keep powered)
  • [ ] Recruit legal / external IR retainer before contacting criminal e-mail
  • [ ] Collect ransom note (.hta / .txt) for IOC hash matching
  • [ ] Rotate all privileged creds (focus on DA, SQL, VMware, Backup operators)
  • [ ] Validate off-line back-up integrity (30 random sample restores)
  • [ ] Patch CVE-2021-26855, CVE-2021-34527, Log4j-2.17, Citrix-CVE-2022-27518
  • [ ] Enforce MFA on ALL external remote access (VPN, VDI, RDP-Gateway, Citrix)
  • [ ] Push YARA rule to EDR to hunt further .eth deposits company-wide
  • [ ] Debrief board & cyber-insurer within 72 h using forensic timeline

Remember: for the current .eth strains, mathematics—not the anti-virus vendor—hold the keys. Invest in resilience, backups, and network segmentation; those remain your most reliable “decryptors.” Stay safe, and feel free to mirror this brief inside your SOC wiki or incident-response run-book.