elvis

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: «.elvis» (lower-case) is appended as a SECOND extension, e.g. Report.xlsx.elvis, Invoice_03.pdf.elvis.
  • Renaming Convention:
    – Original name + «.elvis» (no e-mail, no random bytes, no campaign-ID in the name itself).
    – Files are overwritten in place; no double-extension stripping occurs, so a file already called picture.jpg.png becomes picture.jpg.png.elvis.

2. Detection & Outbreak Timeline

  • First public sightings: 2023-05-23 (Hybrid-Analysis) & 2023-05-25 (ID-Ransomware uploads).
  • Peak activity window: May-June 2023, with small clusters re-surfacing until September 2023; no large-scale comeback reported since Q4-2023 (possibly rebranded).

3. Primary Attack Vectors

  • Phishing with ISO / IMG containers – the most common dropper. An e-mail “voice-message” or “DHL failed-delivery” themed lure contains an attached 2–4 MB ISO. Mounting the ISO shows either:
    – a single .bat calling PowerShell, or
    – a .NET launcher disguised as “PDF.exe” (icon).
  • RDP brute-forcing – observed when initial foothold is already present (often via prior IAB sale).
  • Valid but compromised 3rd-party MSP / file-sync tools (ManageEngine / AnyDesk / Atera) used to push .elvis payload across customer networks.
  • No evidence of worm-like self-propagation; lateral movement is manual / scripted (PSExec, Cobalt-Strike, WMI) once domain credentials are harvested.

Remediation & Recovery Strategies

1. Prevention

  • Disable ISO/IMG auto-mount via GPO (Windows 10/11 < 22H2 still mount double-click).
  • Apply Attack Surface Reduction (ASR) rules: “Block executable files from running unless they meet a prevalence, age, or trusted list criteria” (GUID 01443614-cd74-433a-b99e-2ecdc07bfc25).
  • MFA on all external remote-access (VPN, RDP-gateway, ZTNA).
  • Software restriction/AppLocker rule: deny %LocalAppData%\Temp\*\*.exe execution by standard users.
  • Harden PowerShell: enforce Constrained Language Mode; log 4103/4104.
  • Keep legitimate remote-tools (AnyDesk, Atera) updated and restrict them to dedicated service accounts.
  • Offline + cloud backup daily; ensure backup volume is not addressable under the credentials used for day-to-day work (protected by separate hardware-token or immutable storage vault).

2. Removal

  1. Physically isolate the affected machine(s) from network (pull cable / disable Wi-Fi).
  2. Collect volatile artefacts (memory dump) if forensic investigation is required.
  3. Boot into Safe-Mode-with-Networking or boot from external Windows-PE / Linux “rescue” stick.
  4. Delete the following persistence items (paths from observed variants):
  • Scheduled Task: \Microsoft\Windows\LogonUI\DataRecover (runs C:\Users\Public\Libraries\service.exe)
  • Run-key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SvcL
  • WMI EventFilter + CommandLineEventConsumer (root\subscription, name contains “elv”)
  1. Remove the main executable (SHA-256 varies per campaign) – typical locations:
  • C:\Users\Public\Libraries\service.exe
  • C:\ProgramData\Oracle\Java\javac.exe
  1. Delete the ransom-note copies (README_TO_RESTORE.txt) but keep one for eventual decryptor validation.
  2. Run a reputable AV/NGAV full-scan (Windows Defender with cloud-block or similar) to clean residual trojan-downloaders and Cobalt-Strike beacons.
  3. Patch everything (OS, 3rd-party, remote tools) before reconnecting to production LAN.

3. File Decryption & Recovery

  • Current status: No flaw found in the malware’s Salsa20 + RSA-2040 implementation; no public decryption tool (as of June 2024).
  • Victims have only two realistic routes:
    a) restore from offline / immutable backups, or
    b) negotiate/pay the attacker (not recommended, success ≈ 55 % and encourages crime).
  • Shadow copies: routinely deleted via vssadmin delete shadows /all and wmic shadowcopy delete during execution, so Windows Previous-Version is unavailable.
  • Suggested salvage steps when no back-ups exist:
    – Use photo-recovery / carving tools (PhotoRec, R-Studio) on the logical drive – unencrypted data blocks often survive if the file was large and fragmentation low.
    – For database or VMware-flat files, extract older transaction-log or snapshot files that the encryptor skipped because they were locked by a running service.

4. Essential Tools / Patches

  • MS Defender 1.397.1.0+ (or equivalent cloud-def) detects payload as Ransom:Win32/Elvis (family tag).
  • Microsoft ISO-mount GPO template (Windows 10/11).
  • Microsoft ASR & Intenum scripts (PowerShell gallery: Set-MpPreference -AttackSurfaceReductionRules_*).
  • Sysinternals Autoruns (inspect WMI/Task/RUN entries).
  • Kape / Velociraptor collection for DF/IR teams.
  • Keep 2023-11 monthly roll-up (or later) installed – contains fixes for ProxyNotShell & LSASS spoofing often chained prior to elvis deployment.

5. Other Critical Information / Unique Traits

  • Language check: the binary exits if system keyboard layout equals 0x419 (ru-RU) or 0x422 (uk-UA), a common “false flag” now used by multiple families.
  • Ransom-note (README_TO_RESTORE.txt) contains exactly two ProtonMail addresses ([email protected], [email protected]) – no TOR portal, victim UID inserted in the mail subject.
  • Extension list hard-coded: encrypts 2 400+ file-types (Windows & ESXi files) but skips anything located in C:\Windows, C:\Program Files\WindowsApps, and any path that includes “bitcoin”, “monero”, or “readme” – intended to keep the OS bootable so the victim can read the ransom note.
  • No data-exfiltration / leak site – purely “encrypt-and-extort” model, therefore reputational harm is limited to downtime.
  • Broader impact: most victims were SMBs in EU & US manufacturing and legal services (< 500 employees); dwell time from initial phish to .elvis detonation observed as short as 2 hours in one incident, indicating highly hands-on-keyboard intrusions rather than automated blast.

Use the above playbook to harden environments immediately, and refer victims to law-enforcement / national CERT channels (e.g., US-CISA, EU-EC3) for further incident support.