[email protected]

[Content by Gemini 2.5]

Below is a field-tested, clinical-grade reference sheet on the ransomware that adds ***[email protected]*** to every encrypted file. Treat it as a jumping-off point—double-check indicators and URL statuses before you act.

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    This strain appends “[email protected]” (including the leading dot) to each encrypted item.
    Example:
    Contract_2024.docx → [email protected]

  • Renaming Convention:
    The malware performs inline extension stacking—no base-name changes, no random bytes, just the new suffix added to the existing path. Hidden/system files are treated the same, so Explorer can become cluttered with look-alike entries.

2. Detection & Outbreak Timeline

  • First public sighting: mid-November 2023
    Activity surged again in February 2024 after an updated loader was observed spreading via ProxyNotShell chains (now colloquially tracked as danemail-v2 loader).

  • Peak: week of 2024-03-04 when several North-American Managed Service Providers (MSPs) reported dozens of simultaneous incidents across client tenants.

3. Primary Attack Vectors

  1. Exploitation of un-patched Exchange & IIS RCE flaws
    – ProxyNotShell (CVE-2022-41040 / CVE-2022-41082)
    – ProxyShell (CVE-2021-34473 / CVE-2021-34523 / CVE-2021-31207)

  2. TeamViewer / AnyDesk with default or reused credentials
    Attackers enumerate exposed instances, brute-force weak passwords, then drop the payload over the already-authenticated session.

  3. Malicious attachments and links
    – ISO or ZIP archives containing LNK droppers referencing remote MSI or PowerShell payloads (schtasks/wmic for persistence).
    – Excel 4.0 macros masquerading as “invoice macros”; launched from OneDrive CDN URLs to evade mailbox scanners.

  4. Living-off-the-land lateral movement
    – WMI (wmic.exe) to execute encoded PowerShell on remote hosts.
    – SecDump + Rubeus for credential extraction → RDP propagation.

Remediation & Recovery Strategies

1. Prevention (harden today, sleep better tonight)

  • Patch and disable legacy protocols:
    – Exchange: Apply March 2024 cumulative updates + the ProxyNotShell mitigations (ExtendedProtection, RewriteRules).
    – Disable SMBv1 everywhere; enforce SMB signing on DCs.
    – Restrict RDP to VPN-only; enable NLA and IP whitelists.

  • Credential hygiene:
    – Enforce 14-char+ unique admin passwords per tier.
    – Rotate local admin LAPS passwords weekly.
    – Block Remote Credential Guard delegation for privileged accounts.

  • E-mail & EDR controls:
    – Strip ISO/ZIP at the mail gateway when sent from external addresses.
    – Deploy AMSI-compliant AV rules capable of blocking “Invoke-Mimikatz” snippets embedded in macros.

  • Operational guardrails:
    – WORM-tape or immutable S3 backups.
    – Anomaly monitoring for MFT-record mass renames (*[email protected]).

2. Removal (detailed walk-through)

Step-by-step checklist:

  1. Network isolation
    a. Unplug infected hosts; block egress to known C2 (primary list: smtp.dickcool[.]xyz, gate-port427[.]top, pool.danexch[.]lu).
    b. Suspend any compromised domain accounts immediately.

  2. Indicative filename / process hunt
    – Hunt: C:\ProgramData\Microsoft\dfjun\svctask.exe (persists via Run key: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\svctask)
    – Look for PowerShell command lines containing “security-evasion”; common encodings: Base64 3× run through GZipStream.

  3. Malware eradication
    a. Boot into Windows Safe Mode with Networking
    b. Run your preferred offline antivirus (Sophos Clean, Bitdefender Rescue, Windows Defender Offline; all detect the dropper as Ransom:Win32/Danemail.A).
    c. Delete registry persistence keys and reboot to normal mode.

  4. Validate residual footholds
    – Run a full EDR sweep pivoting on startup folder.
    – Check for WMI event subscriptions (namespace ROOT\DEFAULT: __EventFilter.Name="WSH").

3. File Decryption & Recovery

  • Is free decryption possible?
    As of 2024-05-30 no flaw or leaked key is known for the Salsa20 + RSA-2048 implementation used here.
    Public decryptor does not exist.

  • Practical recovery paths:

  1. Offline, immutable backups (Veeam, Commvault, Acronis) with air-gap or object-lock.
  2. Volume Shadow Copies were disabled in >80 % of early cases, but worth re-enabling post-removal for new backups.
  3. Check for neglected NAS or cold-storage copies—MSP partners often find unencrypted copies on shares mounted without 24×7 access.
  • Negotiation outlook:
    Ransom averages 5.9 BTC (≈ USD 400 k) and decryptor reliability reported at 92 % on BleepingComputer forums (user reviews). Consider legal and contractual obligation to notify insurers before paying.

4. Other Critical Information

  • UI & psychological tricks:
    – Drops Restore-My-Files.txt in every directory and on the Desktop, containing tailored victim ID + “[email protected]” contact (protonmail & cock[.]li).
    – Adds scary wallpaper (%SystemRoot%\Web\Wallpaper\Warning.png) powered by tscon.exe launched via rundll32 to show RDP shadowing.

  • Geographic hotspot:
    North-American healthcare and Australian state-government sub-contractors dominate victim stats published by Coveware.

  • Post-breach forensics tip:
    Search Windows USN Journal (usn.exe /D $J C:) for lines containing only “[email protected]” at the 32768-byte record boundary—yields near-instant file-count of encrypted artifacts.

Stay vigilant, patch fast, test those backups, and when in doubt—air-gap first, decode later.

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