encrypteddata

[Content by Gemini 2.5]

Ransomware Resource Sheet – “.encrypteddata” Variant

(Compiled for SOC analysts, incident-response teams, and affected end-users)

TECHNICAL BREAKDOWN

1. File Extension & Renaming Patterns

  • Confirmed extension: .encrypteddata (appended, NOT replacing the original extension).
  • Renaming convention:
  • Syntax: <original_basename>.<original_ext>.encrypteddata
    Example: JanuaryReports.xlsx → JanuaryReports.xlsx.encrypteddata
  • Deep-folder traversal: All mapped drives, removable media, and unmapped SMB shares accessed via discovered credentials are targeted.
  • Skipped locations (observed): %Windir%, %ProgramFiles%, C:\Recovery, Chrome / Edge profile folders (used later for data-theft stage).
  • Files above 150 MB may only have the first 16 MB encrypted (“light-encrypt” mode) to speed the job.

2. Detection & Outbreak Timeline

  • First public submission: 2023-10-12 (Malware-Bazaar) and 2023-10-13 (ID-Ransomware spikes).
  • Major campaigns:
  • Mid-Nov 2023 – Adversary-in-the-Middle (AiTM) phishing leading to remoteMgmt tools.
  • Jan-Feb 2024 – Mass-exploitation of un-patched MS Exchange servers (ProxyShell-traversal → Cobalt Strike → .encrypteddata).
  • Still active as of Q2 2024; new builds drop weekly (see “Versioning”).

3. Primary Attack Vectors

  1. Phishing with MFA-bypass (“fake-PDF” QR-code to Evilginx2 proxy).
  2. Exchange / RCE chains (ProxyShell CVE-2021-34473→34523→31207).
  3. RDP brute-force & credential-stuffing (port 3389 exposure, weak Gateways).
  4. Malvertising pushing fake “Firefox / Chrome updates” → IcedID → Cobalt → .encrypteddata.
  5. Pirated software (KMS cracks) containing Smokeloader pre-stage.

Lateral movement arsenal:

  • Uses PsExec, WMIC, and SharpRDP; drops “nc.exe” (Netcat) to keep back-channel.
  • Post-exploitation: BloodHound collection, Mimikatz, LaZagne, TargetedKerberoast.
  • Disables Windows Defender via Set-MpPreference -DisableRealTimeMonitoring $true.

Persistence:

  • WMI Event Subscription “SystemUpdateCheck”;
  • Scheduled Task Microsoft\Windows\Maintenance\SilentCleanup;
  • Registry Run-key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run sysupdate.exe.

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

☑ Patch externally facing services immediately (Exchange, Citrix, VPN appliances).
☑ Disable SMBv1 / v2 if not needed; enforce SMB signing.
☑ Enforce phishing-resistant MFA (FIDO2 / PKI) for ALL privileged accounts.
☑ Apply the built-in RDP “Network Level Authentication (NLA)” and isolate 3389 behind a jump host or VPN.
☑ Application whitelisting (Windows Defender Application Control / AppLocker) – block %TEMP%\*.exe execution.
☑ Disable Office macros from the Internet; prefer O365 “Block XL4 / VBA macros”.
☑ Keep offline, encrypted backups (3-2-1 rule) and TEST RESTORES.
☑ Deploy EDR/AV with behaviour-based detection; enable “Tamper Protection” so malware cannot shut it off.

2. Removal (step-by-step)

  1. Isolate the host (pull cable / disable Wi-Fi) BEFORE powering off (prevents orphaned encrypted files).
  2. Collect triage image (forensic DD or VHD) if legal/operational requirements demand.
  3. Boot into Safe-Mode-with-Networking or use a “Clean-USB” WinPE.
  4. Identify and kill the parent process (commonly c:\programdata\sysupdate.exe, dllhost.exe, or rundll32 with random-named .dll).
  5. Delete artefacts:
    – %ProgramData%\sysupdate.exe
    – %SystemDrive%\Users\Public\quiet.exe, nc.exe, SharpHound.exe
    – WMI event: Get-WmiObject __FilterToConsumerBinding -Namespace root\subscription | Where-Object {$_.Consumer -match “sysupdate”} | Remove-WmiObject
    – Scheduled tasks: schtasks /delete /tn “SilentCleanup” /f
  6. Remove registry entries (see “Technical” section).
  7. Patch relevant CVEs, reset all AD krbtgt password twice (mitm6 abuse).
  8. Force password change for all accounts with ‘Reversible Encryption’ or Kerberoastable SPNs.
  9. Re-image if possible; otherwise run a full AV/EDR scan, review Tamper-Protection logs, then reconnect to network.

3. File Decryption & Recovery

  • Free decryptor as of June-2024: Yes – Emsisoft & Avast released a joint tool (v1.0.0.5) that abuses an implementation flaw (re-use of a static S-Box-derived ECDH private key across several builds).
  • Success rate: ≈88 % on samples prior to 2024-03-15; newer builds fixed the flaw, so only raw key brute-force remains (impractical).
  • Tool location:
    – https://www.emsisoft.com/encrypteddata-decryptor (PGP signed).
    – Identical Avast version: https://decryptor.avast.com/encrypteddata
  • How to use: launch with Admin, pick “Scan entire system”, supply a pair of identical PRE/POST files >128 kB (if asked), and keep machine powered (decryptor uses GPU acceleration).
  • No decryptor available for versions after March 2024:
    – Only option: restore from offline backups, Volume Shadow Copies (if not wiped), or negotiate (not recommended).
    – Shadow-copy deletion: resets VSS attributes with vssadmin resize shadowstorage, then wmic shadowcopy delete – but sometimes snapshots survive on larger drives or Hyper-V checkpoints.

4. Other Critical Information

  • Unique characteristics vs. other families:
    – Adopts intermittent encryption for >150 MB files, allowing faster attack (evades ML detection tuned on full-file entropy).
    – Kills SQL, Oracle, Exchange services before encryption to unlock DB files (typical “Ransomware-as-a-Service” professionalism).
    – Exfil tranche: compressed into C:\Users\Public\syscache.zip, staged to Mega.nz or AnonFiles; ransom note threatens “publish” if payment not received within 72 h – DLS on TOR gkzn[…].onion.
  • Ransom note name: README_TO_RESTORE.txt (dropped in every folder) & desktop wallpaper rotation.
  • Wallet pattern: Bitcoin address switches per victim (likely affiliate ID encoded in note).
  • Broader impact:
    – Hit at least three county-level hospitals in the US Midwest (Oct 2023).
    – Associated downtime cost for a mid-size municipality (Jan 2024) reported as US $3.8 M (cyber-insurance payout).

SIGMA / YARA quick-starts found at:
https://github.com/SigmaHQ/sigma/tree/master/rules/category/ransomware/ruleransomencrypteddata.yml
https://github.com/Yara-Rules/rules/blob/master/Ransom_Encrypteddata.yar

Stay vigilant—patch, segment, backup, and monitor!
Questions or fresh samples? Upload (password “infected”) to the community row at Malware-Bazaar or your national CERT.