[email protected]

[Content by Gemini 2.5]

Understanding & Defeating the “[email protected]” Ransomware

⚠️ This variant belongs to the GlobeImposter / Chaos / Void family that has been circulating since 2016 under many extensions and contact addresses.
At present no free universal decryption tool exists, but portions of files seized from older campaigns have been cracked in the past.
Time and a disciplined recovery approach matter—act fast!

Technical Breakdown

1. File Extension & Renaming Patterns

  • Extension applied: [email protected] (note: the string [email protected] is literally part of the injected dual extension).
  • Pattern example:
    Vacation2023.jpg → [email protected]
    Inside every folder you will also find two ransom notes:
    • how_to_back_files.html
    • info.hta opened via scheduled task on every logon.

2. Detection & Outbreak Timeline

  • First wave: GlobeImposter started using [email protected] in February 2022; the string [email protected] snuck into later source-code forks of Chaos/Xxx。
  • Ramp-up observed: March–June 2022 – hundreds of MSP/municipality infections after RDP brute-forcing campaigns in Spain and LATAM.

3. Primary Attack Vectors

| Vector | Technique | Real-world scenario |
|——–|———–|———————|
| 1. Brute-forced RDP | Uses leaked or reused passwords; attackers open port 3389 on the firewall or tunnel via ssh. | Typical for small-to-mid-size organisations that published 3389 to the internet. |
| 2. Phishing email with ZIP + ISO | Lure: “Banco-santander_devolverfactura.zip”; ZIP contains a 7 MB ISO; ISO mounts and launches a .NET loader which downloads the core PE file (SHA-256: 5f1e5903…). |
| 3. ProxyLogon / ProxyShell | After exploiting un-patched Exchange servers, attackers drop a Cobalt-Strike beacon, then PSExec svchosts.exe (GlobeImposter). |
| 4. Wrapped in fake cracks/tools | Telegram bots distributing malicious KMSAuto++ or Adobe cracks with the same malware file. |

Remediation & Recovery Strategies

1. Prevention (Must-Have Checklist)

  1. Remove RDP/TCP-3389 from external exposure; move to VPN with MFA.
  2. Patch Microsoft Exchange before May 2021 (MS17-010, CVE-2021-34527, etc.).
  3. Enable Windows Controlled-Folder-Access or equivalent ransomware-guard product.
  4. Create 3-2-1 backups: 3 copies, 2 different media, 1 off-site offline.
  5. E-mail gateway – block ISO, CHM, HTA macros; force attachments to detonate in a sandbox.
  6. Least-privilege with LAPS for local admin passwords; audit high-privilege accounts weekly.

2. Infection Cleanup (Run once you have image-level backups)

  1. Isolate: Power off every affected host; block lateral movement ports on the switch (TCP 139, 445, 3389).
  2. Boot a recovery OS (Windows PE or Linux LiveCD). Mount the disk read-only and copy the ransom notes for incident gathering.
  3. Scan offline:
    • Malwarebyte­s Offline, AVG Rescue CD, or Kaspersky AV Rescue Tool – both flag generic GlobeImposter components already.
    • Preference: Use PowerShell Get-FileHash to cross-check suspicious binaries in temp dirs or \Windows\System32\ where persistence is set (Winlogon\Shell, RunOnce).
  4. Clean persistence:
    • Delete registry keys:

    HKCU\Software\Microsoft\Windows\CurrentVersion\Run
    HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run

    • Remove scheduled tasks via schtasks /delete.
    • Empty %TEMP%\*.exe, %windir%\*.exe with random hex-like names.
  5. Change all credentials – especially domain admin accounts accessed during the breach interval.

⏱️ Only after the final clean scan, re-image or rebuild on known-good media.

3. File Decryption & Recovery

  • Current Status: There is NO publicly available decryptor for the [email protected] spinoff (encryption is RSA-2048 + ChaCha20).
  • Partial salvation:
    • If your variant reused the slightly older ChaCha20 hard-coded key (some chaos forks did), Dr.Web’s VirusDecryptor might recover 0–512 KB at the start of each file.
    • Test: Drag a single JPG into Dr.Web’s decryptor with “-detect” switch to see if it finds a static key.
  • If backups or shadow copies don’t exist, move encrypted material to cold storage—don’t delete them in case a flaw or future leak allows recovery. ⚠️ Do not pay – you may never obtain a working decryptor, payments finance further crime.

4. Other Critical Information

Unique Behavior Tips

  • Network propagation: Uses PSExec or PDQ Deploy to push itself to \\admin$\svchost.exe if it sniffs admin credentials (common chaos practice).
  • Ransom note language: appears in Spanish 🇪🇸, but campaigns have run in English, Portuguese and Chinese too—language alone is not a reliable pivot.

Wider Impact

  • A Spanish hospital (Virgen del Rocío) and multiple Latin-American state-owned oil companies were crippled in early 2022 chains—downtime ranging 72–240 hours in environments with sporty legacy Win-Server 2008 R2 boxes.
  • Supply-chain angle: once inside the MSA DC they pulled MSSQL .bak files (dumped credentials, payroll db, patents) before encryption—assume data exfiltration took place and report GDPR / HIPAA incidents accordingly.

Cheat-Sheet (one-print page)

□ Isolate hosts, pull cables  
□ Collect incident pack: notes, binaries, logs  
□ Use KasperskyRescue; nuke HKLM\…\Run  
□ Restore from offline backup  
□ Patch RDP/Exchange, rotate creds  
□ Store encrypted files offline → wait for future leak  
□ No decryptor – do NOT pay ransomware actors

This guidance is provided on a best-efforts basis; forensic triage may uncover case-specific keys or logs that change the landscape.