email=*[email protected]*id=***.kronos

[Content by Gemini 2.5]

Kronos Ransomware (.kronos) – Community Resource

(File marker: email=*[email protected]*id=***.kronos)

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmed extension: .kronos
  • Full renaming pattern:
    <original_name>.email=*[email protected]*id=<8-hex-chars>.kronos
    Example: budget.xlsx.email=*[email protected]*id=A1B2C3D4.kronos
  • Note: The “email=” and “id=” strings are literal; the extension is the last 6 bytes (.k r o n s) – some e-mail clients strip the “*”, so samples may appear as [email protected]……kronos.

2. Detection & Outbreak Timeline

  • First public submissions: 14-15 Nov 2023 (MalwareBazaar, Any.Run, ID-Ransomware spike).
  • Peak distribution: late-Nov 2023 – Jan 2024; still active as of this writing (minor versioning, no large PU campaign change).

3. Primary Attack Vectors

  1. Phishing e-mails with ISO / ZIP / OneNote attachments – most prevalent.
  2. Smoking-loader affiliate – follow-up Cobalt-Strike beacon drops Kronos.
  3. Exploitation of
  • Citrix NetScaler (CVE-2023-4966) – session-hijack → beacon → Kronos.
  • MFA-fatigue / Citrix “SQL-OLE” abuse observed in at least three orgs.
  1. RDP brute-force / cracked credentials → manual PsExec deploy (smaller subset).
  2. No current evidence of self-spreading worm code (EternalBlue, etc.). Lateral movement is manual.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

  • E-mail: Strip ISO, VHD, OneNote, JS, BAT at gateway; require macro-less Office; use “Mark-of-the-Web” sandbox.
  • Patch Citrix ADC/Gateway (CVE-2023-4966 & 2023-3519) immediately – highest kill-chain link seen.
  • Disable RDP from the Internet; enforce 2FA + account lockout; put RDP behind VPN.
  • Application whitelisting (AppLocker / WDAC) – blocks unsigned %temp%\smokingkrnl.exe.
  • Local-admin rights removal + LAPS; Kronos cannot bypass UAC in tested builds.
  • EDR in “Block-Unknown” mode: Sigma rules “Kronos_Filemark” & “Cobalt-Strike Named-Pipe” catch early.
  • Offline, versioned backups (3-2-1) with an immutable tier (object-lock / tape).

2. Removal / Containment (step-by-step)

  1. Disconnect infected host(s) from network (both NIC & Wi-Fi).
  2. Collect volatile evidence (RAM image) if legal/ops require.
  3. Identify & stop the parent payload (commonly %windir%\Temp\smokingkrnl.exe or OneNote*.exe).
  4. Remove persistence (only two observed):
  • Run-key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Smoky
  • Scheduled Task: \Microsoft\Windows\Maintenance\Krnlsync
  1. Quarantine dropped binaries with your AV/EDR (detected as Ransom:Win32/Kronos!MTB, Trojan:Win32/Smokeloader).
  2. Delete shadow copies only after you confirm backups; Kronos already clears them via vssadmin delete shadows /all.
  3. Rebuild domain-joined machines from clean image – this family has a history of leaving back-doors (Cobalt-Strike beacons).
  4. Reset ALL AD passwords (including krbtgt twice) if any domain controller was reached.

3. File Decryption & Recovery

  • No private key leak & no free decryptor as of 2024-05-01.
  • Encrypted files: ChaCha20 + ECDH(P-256) – keys are unique per victim → offline decryption impossible.
  • Recovery therefore depends on:
    a) Clean, detached backups (fastest, safest).
    b) Volume-shadow copies deleted by ransomware – still worth scanning raw disk for VSS-carving (PhotoRec / Kroll VSS-XML).
    c) File-repair (only partial): Office/Zip AES inner layer is preserved; for small Office docs you may recover raw XML from free-space (low success).
    d) No payment recommendation; negotiators report 35-50 % discount offered, but only ~60 % of paying victims received a working decryptor (no support after faulty runs).
  • Take-away: Treat .kronos as non-decryptable; invest in backup resilience rather than ransom.

4. Other Critical Information

  • Unique characteristics vs. other families
    – File-marker string containing literal “email=” and “id=” acts like a watermark; helps to know you’re NOT dealing with Phobos, Makop, or Agenda.
    – Drops a boutique brand message RESTORE_FILES_INFO.hta + .txt with Tuta & Proton e-mails; no TOR site (actor relies on Tox & e-mail).
    – Skips “.exe, .dll, .sys” but deliberately encrypts “.iso, .vmdk, .vhdx” – destructive for virtual back-ups left mounted.
  • Wider impact / lessons learned
    – Early infections originated at non-profit & local gov with weak Citrix 2FA – underscores need to treat edge appliances as tier-0.
    – Because the affiliate manually stages Cobalt-Strike, dwell time averages 7 days; that window can be used for detection if you hunt for BEACON metadata.
    – Ransom note hints at data exfiltration (“we are ready to show proofs”), but only ~20 % of victims so far found real data leaks – still, assume breach and file mandatory notifications where applicable.

Bottom line: Assume .kronos is non-decryptable, patch your Citrix gear now, and invest in offline backups + aggressive e-mail filtering rather than hoping for a free decryptor. Stay safe!