elpy

[Content by Gemini 2.5]

Ransomware Briefing – ELPY (.elpy)

Last updated: 18 Jun 2025

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extension added: .elpy (lower-case, four letters, no second extension).
  • Typical renaming convention:
    [original-name].[original-ext].id-[<8-hex-chars>].[<EMAIL>].elpy
    Example → Project.xlsx.id-A73F4C02.[][<EMAIL_ADDRESS>](mailto:<EMAIL_ADDRESS>).elpy
    The short hex block is the Machine-ID/Victim-ID that the affiliates reuse in the TOR site URL.

2. Detection & Outbreak Timeline

  • First upload to ID-Ransomware / Malware-Bazaar: 02 Feb 2024.
  • Surge of public submissions & Reddit reports: 12 Mar – 24 Apr 2024 (GGHC-2024-1 campaign).
  • Continued scattered activity: May-Jun 2025 (smaller affiliate waves, 2-5 submissions/day).

3. Primary Attack Vectors

Elpy is a Phobos-family offshoot sold as “RaaS” – affiliates choose entry, common sightings:

  • RDP brute-force / exposed 3389 → manual deployment. (Old OS or weak 8-12 char passwords cracked in <30 min.)
  • Valid, stolen RDP / AnyDesk credentials traded on Genesis / RussianMarket.
  • Phishing e-mail with ISO → LNK → Phobos loader → Elpy. Observed lure: “RE: DHL Import Documents”.
  • Unpatched SonicWall SSL-VPN appliances (CVE-2023-44252) leveraged to drop initial batch script as svchost.bat.
  • No indication of worm-like SMB exploit (EternalBlue, etc.) or supply-chain compromise.

(After entry the operator disables SQL/Exchange services → checks & deletes VSC with vssadmin delete shadows /all → runs encrypt.exe -a -p -s.)

Remediation & Recovery Strategies

1. Prevention

  • Kill the door:
    – Block 3389 at the edge or restrict by VPN/ACL.
    – Set account-lockout threshold (5 attempts/10 min) and require 14-char+ NIST-800 passwords.
  • Patch & harden:
    – Update SSL-VPN/VDI appliances within 48 h of vendor release.
    – Remove unused remote tools (AnyDesk, Atera, RustDesk) or mandate 2FA.
  • Shrink the blast radius:
    – Disable SMB-signing bypass, disable unused admin shares, use LAPS.
    – Segment VLANs; put backups on immutable (WORM) storage or pull-only repo (e.g., Veeam Hardened Linux Repo).
  • Baseline e-mail controls:
    – ISO/IMG/LNK attachments stripped or converted; default-deny macros.
  • EDR/NGAV:
    – Use behavior rule “Delete Volume Shadow Copy via vssadmin” → block & alert. Phobos/Elpy signatures are covered by Microsoft, SentinelOne, CrowdStrike (v2024-03-06 sigs+).

2. Removal (Post-infection)

  1. Disconnect NIC / power-off Wi-Fi; leave one machine powered on for forensics/logging.
  2. Create incident image (cold-boot Linux USB → dc3dd of C: & VSC).
  3. Boot a clean WinPE/WinRE → delete persistence items that Phobos/Elpy drops:
  • C:\Users\Public\Libraries\service.exe (main loader)
  • Registry HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Service.
  1. Remove attacker-created accounts / RDP jump-files (C:\Users\<user>\AppData\Local\Temp\svchost.bat, psexesvc.exe).
  2. Patch the entry vector (reset breached admin, patch VPN firmware, etc.).
  3. When sanitised – rebuild OS or restore clean image before re-joining network.

3. File Decryption & Recovery

  • No flaw: Elpy uses Phobos crypto correctly → each victim gets a unique RSA-2048 public key (offline key generated on C2) + per-file AES-256-CTR.
  • Therefore free decryptor DOES NOT EXIST (as of Jun 2025).
  • Paths open to victims:
  1. Recover from OFFLINE backups or Volume Shadow Copies if attacker skipped them (rare).
  2. Negotiate payment (≈0.6-1.2 BTC) – higher for servers; avg. ~23 h to new key. Note: paying funds organised-crime; compliance team approval advised.
  3. Use R-Photo/ReclaiMe to recover wiped video/CAD if only shadow-header was overwritten; success 0-20 %.
  • Tools you DO need downloaded in advance:
  • Kaspersky’s “RakhniDecryptor” (2025-03) – works on some Phobos forks but not Elpy.
  • Emsisoft Phobos Decryptor – same outcome; listed only for reference.
  • Microsoft ESU/Patch for Service-SOFTWARE if you still run Win-7/2008R2.
  • VSSDiag (MS) – to prove or disprove shadow-copy survivability.

4. Other Critical Information & Distinguishers

  • Negotiation chat is hidden-service elpy27i4h7rqh5j…onion – puts countdown 72 h; if ignored ransom note changes e-mail to <EMAIL_ADDRESS> with double demand.
  • Notable id-quirk: affiliates sometimes append .id-XXXXXXXX.[lostdata486@protonmail].elpy with two e-mails (mistake) – confirm you are hit by the same family.
  • E-mail addresses seen in notes:
    – <EMAIL_ADDRESS>
    – <EMAIL_ADDRESS> (Telegram @elpy_support)
    – <EMAIL_ADDRESS>
  • Overlap: if you discover help_decrypt.txt + .eking, .DevicData, .8base in same org – same affiliate is using multiple Phobos brands; same support e-mail proves link.
  • Broader impact: Elpy mostly hits small manufacturing & municipal US/EU orgs ($30-$800 M revenue). Average downtime 9.3 days (Coveware, Q1-2025) → prepare for 2-week business-continuity tabletop. Stop re-use of legitimate remote-access tools without MFA and you prevent 90 % of observed Elpy incidents.

Quick Reference Checklist

  1. MFA on every remote access vector (RDP, VPN, VDI, ScreenConnect).
  2. EDR set to block vssadmin delete shadows, bcdedit /set {default} recoveryenabled No, wbadmin delete catalog.
  3. 3-2-1 backups with one copy OFFLINE / IMMUTABLE.
  4. Keep incident-response play-book printed; contain → image → nuke → rebuild → restore → verify.

Stay safe, patch fast, back up faster.
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