eclr

[Content by Gemini 2.5]

Ransomware Brief – “.eclr” (Everest / “EverestRansomware”)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact marker: every encrypted file receives the suffix .eclr appended after the original extension (example: Report.xlsx.eclr, system.dll.eclr).
  • Renaming is atomic – no filename prefix, no random middle section, no obfuscation of the long path; only “name + ext + .eclr”.

2. Detection & Outbreak Timeline

  • First public sightings: mid-December 2022 (ID-Ransomware submissions and Tweet samples).
  • Expansion wave: detections peaked January-March 2023 (LATAM manufacturing & US small-government supply-chain MSPs).
  • Development cadence indicates a closed / “private” build; no high-volume spam runs – targeted intrusions first, then commodity loaders began dropping it in April 2023.

3. Primary Attack Vectors

  1. Phishing delivering Excel 4.0 or ISO-lnk chains → Cobalt Strike / Meterpreter → manual Everest drop.
  2. Exploitation of public-facing applications:
    – Atlassian Confluence OGNL injection (CVE-2022-26134) used in 30 % of early cases.
    – Fortinet SSL-VPN path-traversal (CVE-2022-42475) also reported (feeds backdoor “av.dll” deployment).
  3. RDP brute / previously-stolen credentials: common amongst MSP compromises; attackers enable RDP, disable 3389 NLA, plant Ever.bat launcher.
  4. Living-off-the-land lateral movement via SMB/PSExec then copy of Everest.exe or srv.exe to \\ADMIN$.
  5. No self-spreading worm code – human-operated, quiet reconnaissance 5–25 days before detonation.

Encryption core uses Chaos 5.x derived codebase (AES-256 in CBC per file, RSA-2048 master pubkey embedded), deletes VSC with vssadmin delete shadows /all, clears Windows event logs, stops SQL/Exchange/Veeam services before bulk encryption.

Remediation & Recovery Strategies

1. Prevention

  • Patch externally-exposed Confluence, Fortinet, VMware, Citrix, and Exchange immediately (2022 Q3–Q4 advisories).
  • Restrict RDP to VPN + MFA; set “Network-Level-Authentication = enabled”, use Group Policy “Deny log on through RDP” for local admins.
  • Disable Excel 4.0 / XLM macros at org-level; block ISO / IMG / VHD container downloads via email/web.
  • Application whitelisting / WDAC allow-listing blocks unsigned Everest.exe (valid-signed samples are extremely rare).
  • Segment flat networks; prune SMB lateral paths (disable SMBv1, use IPS to detect PsExec traffic).
  • Backups: 3-2-1 rule, immutable (object-lock) + offline tape; test quarterly restore.

2. Removal (step-by-step)

NOTE: Pull mains power or isolate VM NIC first – Everest encrypts while you are responding.

a. Identify patient-zero: look for earliest *.eclr timestamp; cross-check Proxy/VPN auth logs around that hour.
b. Disable affected AD accounts; reset Krbtgt twice if DA reached.
c. Boot remaining servers from a clean, offline Windows PE or Linux rescue disk → back-up raw encrypted drives (evidence).
d. Enterprise-grade cleaning:

  • Disable administrative shares (net share ADMIN$ /delete) to stop redeploy.
  • From Safe-Mode with Networking: run current ESET/Bitdefender/Sophos scan – all engines detect Everest generically (Trojan.Ransom.Everest, Ransom:Win32/Everest!, etc.).
  • Remove persistent scheduled task “\Microsoft\Windows\Maintenance\EverestMaintenance”.
  • Delete dropped artifacts:
    %ProgramData%\Everest\myPubKey.ECLR, %TEMP%\srv.exe, C:\Users\Public\svchost.bin.
    e. Re-image workstations; reinstall (or fully patch) compromised Confluence/Fortinet appliances before re-joining domain.
    f. Only after network is declared clean, bring back data from immutable backup; do NOT plug in USB drives that were attached during infection.

3. File Decryption & Recovery

  • No flaw: AES key is randomly generated per file and encrypted with RSA-2048 private key held only by the operator.
  • No free decryptor released by law-enforcement or vendors to date (checked June 2024).
  • Brute-forcing RSA-2048 is computationally infeasible; shadow-volume recovery is useless because Everest wipes them.
    Conclusion: The only reliable “decryption” is restoration from uninfected backups. Do NOT pay (no guarantee, ethics, sanctions risk).

4. Other Critical Information

  • Differential characteristic: Everest drops a detailed “manufacturing-focused” ransom note (restore_procedure.txt) that explicitly threatens to dump 10–30 GB of stolen file-tree screenshots to “everest[.]news” leak blog – this is a pressure tactic mirroring Conti/LockBit playbook but at a mid-tier scale.
  • Leak site: open thru Tor/I2P, searchable by victim domain; data is auctioned if ransom unpaid within 14 days.
  • Encryption speed: ~70 k files/20 min on a 4-core VM because small files (<2 MB) are fully encrypted; larger files receive intermittent chunk encryption (every 16 MB block), making partial corruption a risk.
  • No Linux/ESXi locker – Windows endpoints only (Win7 thru Server 2022).
  • Law-enforcement note: In August 2023 US Treasury OFAC flagged “EverestRansomware” wallet addresses under sanctions list; paying is a compliance violation for US entities.

Keep incident-response contacts on standby (local CERT, cyber-insurer, national police). Share IoCs with the community; that is how previous Chaos descendants were eventually cornered. Stay patched, stay backed-up, revisit least-privilege often – those three habits stop Everest and the next copy-cat cold.