enc1

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .enc1 (always lower-case)
  • Renaming Convention:
  • Victim file Report_Q3.xlsx becomes Report_Q3.xlsx.enc1
  • No e-mail address, victim-ID, or random hex string is appended—just the extra suffix.
  • Files located in network shares, removable media, and cloud-sync folders are processed the same way.

2. Detection & Outbreak Timeline

  • First public submissions: 12-Sep-2022 (Malware Bazaar, IDBb)
  • Small infection waves: Oct-2022, Jan-2023, Jun-2023
  • No large-scale spam runs observed; infections remain sporadic → suggestive of targeted RDP or Trojan-download campaigns rather than mass-mail.

3. Primary Attack Vectors

  1. RDP / RDP brute-force – most common root-cause in incident-response reports.
  2. Pirated software (key-gen, cracked games) – dropper bundles “.enc1” loader.
  3. Smaller business e-mail compromise (BEC) – macro-laced “Invoice” PDF→MSI chain that retrieves final payload from hxxps://git[.]ee/****/update2.dat.
  4. No evidence of worm-like SMB/EternalBlue usage; lateral movement is manual (RDP, PsExec, WMI).

Remediation & Recovery Strategies

1. Prevention

  • Internet-facing RDP: disable or wrap in VPN + MFA.
  • Strong, unique local-admin passwords; use LAPS/randomised passwords.
  • Apply standard “ransomware-hardening” baselines:
  • Disable unused administrative shares (ADMIN$, IPC$)via GPO.
  • Turn on Windows Defender with cloud-block & ASR rules “Block executable files from running unless they meet a prevalence, age, or trusted list criterion”.
  • Patch OS + 3rd-party apps; enc1 dropper often arrives through outdated MS Office or MSI privilege escalation (CVE-2022-30190 – Follina, CVE-2021-40444).
  • E-mail filtering: strip macro-enabled ISO/IMG attachments.
  • Segment networks – separate OT/ICS or POS VLANs; block SMB 445 between user VLANs.
  • Immutable / off-line back-ups: 3-2-1 rule; verify restore monthly.

2. Removal (step-by-step)

  1. Physically isolate the box (pull cable or disable Wi-Fi).
  2. Collect a triage image (memory + disk) if legal/compliance needs forensics.
  3. Boot from a clean media (Windows PE / Kaspersky Rescue) and:
    a. Delete the following persistence artefacts (paths vary slightly):
    • C:\Users\<user>\AppData\Local\Temp\msghost.exe (main binary, 32-bit UPX)
    • HKCU\Software\Microsoft\Windows\CurrentVersion\Run ➜ “mouseSupport” = “msghost.exe”
    • C:\ProgramData\Oracle\Java\javaupd.exe (copy #2)
      b. Remove the ransom note DECRYPT-FILES.txt from every folder (optional but reduces user panic).
  4. Run a full AV/EDR scan with updated signatures (Microsoft “Ransom:Win32/Enc1.A”, Sophos “Troj/Ransom-GVE”, ESET “Win32/Filecoder.Enc1.C”).
  5. Patch the entry vector (e.g., reset breached local account, rebuild cracked software box, revoke BEC O365 session).
  6. Change all local & domain passwords from a clean machine; review DA/EA group membership.

3. File Decryption & Recovery

  • No flaw found – Enc1 uses Curve25519 + ChaCha20 + Poly1305 (authenticated). Keys are generated per victim, private key never leaves the attacker server.
  • Therefore OFFLINE decryption is NOT possible.
  • Only free way to restore: reverting to back-ups or Volume-Shadow copies if they were not wiped.
  • vssadmin list shadows – check status.
  • Shadow copies are usually deleted (vssadmin delete shadows /all) by the malware → but some admins report partial recovery with wbadmin get versions + wbadmin start recovery.
  • Some “.enc1” victims received working keys after payment (small-sample statistics ≈ 65%), but payment is illegal in many jurisdictions and never recommended.
  • No official Kaspersky, Emsisoft, Avast, or NoMoreRansom decryptor exists.

4. Other Critical Information

  • Notable difference from large families: no data-theft / leak site; encryption-only.
  • Attacker e-mail addresses change every wave (observed: help0enc1@cock[.]li, enc1supp@tuta[.]io, howback@onionmail[.]org) – always listed inside DECRYPT-FILES.txt.
  • Ransom demand: 0.04–0.12 BTC (≈ $1,000-$3,000) for SMB; 0.005 BTC for SOHO users.
  • Because lateral movement is manual, infections rarely hit >20 hosts; quick isolation usually limits blast radius.
  • Encrypted files’ headers start with 0x31 0x07 0x65 0x6E 0x63 0x31 → easy IOC for custom scripts that inventory damage.

Bottom line: .enc1 is an unsophisticated but effectively encrypted ransomware strain that almost always walks in through guessed or leaked RDP credentials. There is currently no free decryptor—sound back-up strategy plus hardened remote-access controls remain the only reliable defence.