everest

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    The Everest ransomware family appends the fixed suffix .EVEREST to every encrypted file (e.g., Budget_2024.xlsx → Budget_2024.xlsx.EVEREST).
  • Renaming Convention:
    Original name is preserved; only the single extension is added. No e-mail address, victim ID, or random hex-string is inserted, making quick visual triage easy.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First samples submitted to public repositories on 22 Dec 2021. Notable SMB-focused campaigns appeared March–April 2022; still circulating in 2024 (latest large wave reported 18 Jan 2024).

3. Primary Attack Vectors

  1. RDP brute-force / credential stuffing (still #1 – port 3389 exposed to Internet).
  2. Phishing e-mails with ISO/IMG attachments containing the .NET loader.
  3. Weaponised PSExec & WMI once inside the LAN (lateral movement).
  4. Exploitation of un-patched Citrix ADC/Gateway (CVE-2019-19781) and occasional SonicWall VPN flaws.
  5. Mimikatz + Kerberoasting to harvest domain admin hashes before deployment.

Remediation & Recovery Strategies:

1. Prevention

  • Close or shield RDP (port 3389) behind VPN + MFA; enforce 15-char+ complex account-lockout policies.
  • Disable SMBv1 company-wide—Everest’s internal spread module still tries SMB1 pipes first.
  • Patch externally facing apps: Citrix, SonicWall, Fortinet, Exchange, Log4j.
  • Application whitelisting (WDAC/AppLocker) blocks the unsigned .NET launcher Everest drops.
  • Mail-gateway rules to quarantine ISO, IMG, and “.one” attachments.
  • Secure, offline (immutable) backups (3-2-1 rule, Veeam hardened repo, AWS S3 ObjectLock, Azure immutable blobs).
  • EDR / Next-AV with behavioural detection (CrowdStrike, SentinelOne, Defender for Endpoint, etc.) tuned for MITRE T1486 “Data Encrypted for Impact”.

2. Removal

  1. Physically disconnect the box from LAN/Wi-Fi → stop encryption in progress.
  2. Boot into Safe Mode with Networking or mount drive offline.
  3. Delete persistence artefacts:
  • C:\Users\Public\Libraries\service.exe (primary dropper)
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run → “EverestMonitor”
  • Scheduled Task “EverestSysHelper”
  1. Remove malicious service “EverestHelpService” (sc stop & sc delete).
  2. Wipe Volume-Shadow copies only AFTER verifying you have clean offline backups (Everest runs vssadmin delete shadows /all).
  3. Run a full scan with updated AV/EDR; then rebuild/re-image if root-cause analysis shows credential theft & lateral movement.

3. File Decryption & Recovery

  • Recovery Feasibility:
    No flaw found so far; Everest uses Curve25519 + AES-256 in ECIES mode, keys are uniquely generated per victim and only the attackers hold the private key.
    There is NO free public decryptor.
    Only recovery paths:
    a) Clean offline backups
    b) Paying the ransom (not recommended – no guarantee, may violate regulations)
    c) Voluntary release of master keys by the actor (historically never done for Everest)
  • Essential Tools/Patches:
  • Kaspersky VirusRemoval Tool, ESETOnlineScanner or MS Defender Offline for removal.
  • CVE-2019-19781 / CVE-2020-1472 etc. vendor patches to block re-entry.
  • GPG-based backup verification scripts to ensure backup integrity before restore.

4. Other Critical Information

  • Additional Precautions:
    Everest is “human-operated”, not an automated worm. Operators spend 2-7 days inside networks harvesting data with rclone, MegaSync, and FileZilla before triggering encryption. Expect double-extortion: they publish stolen documents on their Tor blog “Everest-News”. Negotiation chat is handled via the Tox ID left in the ransom note (!!!READMYTOX!!!.txt).
  • Broader Impact:
    Posted leaks have included law-enforcement files, hospital PHI, and DoD supplier data, leading to U.S. federal advisories (Alert AA22-120A). Because of their tendency to re-sell network access to other ransomware crews, cleaning an Everest incident frequently prevents a follow-on Conti or Zeppelin attack.

Stay vigilant, patch fast, and keep those backups immutable!