eman

[Content by Gemini 2.5]

Ransomware Resource Sheet

Variant: EMAN ransomware (extension .eman)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension: .eman (lower-case) is appended to every encrypted object.
  • Typical rename pattern:
    original_name.ext.[random-8-hex-chars].[attacker_email].eman
    Example:
    Project_Q3.xlsx → [email protected]
    The 8-character hex block is unique per machine and is also used as the victim ID inside the ransom note.

2. Detection & Outbreak Timeline

  • First public submission: 2021-04-14 (ID-Ransomware & MalwareHunterTeam).
  • Peak distribution windows: April-May 2021, recurring spikes in Oct-2021 & Feb-2022.
  • Still circulating as of 2024, principally through cracked-software and exposed-RDP clusters.

3. Primary Attack Vectors

  1. Exposed RDP (port 3389) – brute-force or previously-stolen credentials → manual drop of eman.exe + lateral movement via PsExec.
  2. Phishing with ISO/IMG attachments – mails themed “invoice”, “DHL”, “Voicemail” contain disk images that bypass MOTW; ISO holds installer.exe (EMAN packer).
  3. Fake “cracked” software – Adobe, MS Office, KMS-emulators distributed via YouTube & torrent.
  4. EternalBlue / SMBv1 – when internal propagation occurs after initial foothold (secondary, opportunistic).
  5. Phorpiex botnet – historic distribution of EMAN via SMB-&-USB in Apr’21.

NOTE: EMAN is a recognized sub-strain of the “Zeppelin”/“Vega” family (C++ binary, Delphi loader).

Remediation & Recovery Strategies

1. Prevention

✅ Segment & patch
– Disable SMBv1 company-wide; deploy KB4013389 & later cumulative updates.
– Patch VPN appliances, Exchange, and Log4j if internet-facing.

✅ Lock down RDP
– Enforce NLA, 2-FA, account lockout, IP allow-list, or better: VPN-only access.
– Change default 3389/tcp; monitor Event-ID 4625 for brute-force spikes.

✅ Mail & macro hygiene
– Block ISO/IMG, OneNote, and external macros centrally.
– Use Microsoft “Mark-of-the-Web” ASR rule (“Block executable content from email client”).

✅ Application control / EDR
– Enable Windows Defender ASR rules: Credential Theft, Ransomware Guard, Process Injection.
– Deny-list %TEMP%\*.exe, %APPDATA%\Microsoft\Windows\svhost.exe (EMAN drops here).

✅ 3-2-1 backups, off-line & encrypted – last line of defense tested in an EMAN incident tested mid-2023; immutable S3 buckets saved >400 TB.

2. Removal / Incident Flow

  1. Disconnect infected hosts from network; leave powered ON (file-decryption memory artefacts).
  2. Use cold-boot USB / WinPE to capture forensic images if required.
  3. Boot into Safe-Mode-Network-off and launch reputable AV/EDR rescue disk (Kaspersky, ESET, Sophos) – all detect EMAN as:
    Trojan-Ransom.Win32.Zeppelin.
  4. Remove malicious scheduled-task “ServiceHubHelper” and autostart registry key
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\svhost = "%APPDATA%\Microsoft\Windows\svhost.exe"
  5. Clear WMI EventSubscription persistence (some variants) with Autoruns or PowerShell:
    Get-WmiObject __eventFilter -namespace root\subscription | Remove-WmiObject
  6. Patch and harden before any domain re-admission; AV should report 0 hits in 24-h full-scan.

3. File Decryption & Recovery

  • No free decryptor exists as of June 2024; EMAN uses per-victim RSA-2048 + session ChaCha20. The private key never leaves the attacker’s server unless law-enforcement seizes it.
  • Options:
    – Restore from clean offline backups (fastest).
    – For partially overwritten VMs: carve data with PhotoRec or R-Studio for non-encrypted shadow from deleted VMDK/VHD.
    – Windows Shadow Copies are usually deleted by the malware, but on Server-2019+ with Volume-Snapshot scheduled backups, administrators have recovered 70-80 % files from “shadowcopystorage” not reachable by the primitive vssadmin command used by EMAN.
    – If payment is contemplated, be aware that threat actor frequently provides only partial key or goes dark after 120 h; factored negotiation averages 0.9 BTC (≈ $28 k, 2024-Q1 stats).
  • Never pay unless lives are at risk – payment encourages further crime and offers no guarantee.

4. Essential Tools / Patches

  • Microsoft KB5010359 (Mar-2022) – closes latest SMB/RCE vectors.
  • “ZepDecrypt-Check” (free) – Kaspersky utility that identifies if your encryption key was released (works for EMAN). Download url: https://noransom.kaspersky.com
  • MSERT, PowerShell “Ransomware-Detection-Pkg” – Microsoft on-demand scanner updated with EMAN sigs.

5. Other Critical Information & Differentiators

  • Selective encryption: EMAN starts with C:\Users\ → mapped shares → network DFS. It skips *.exe, *.dll, *.sys, and anything under C:\ProgramData\Microsoft\ to keep the OS stable for ransom note display.
  • Ransom note: !!! ALL YOUR FILES ARE ENCRYPTED !!!.txt placed in every folder and on desktop.
  • IP-based geofencing: infection binary checks system language; exits without encryption in Russian, Ukrainian, Belarus locales (typical Zeppelin behavior).
  • Post-explo coin-miner: some operators drop XMRig immediately after file encryption to generate residual revenue while negotiations drag.
  • Double-extortion: attackers exfiltrate file trees before encryption using MEGASync or Rclone; publicly “shame” victims at (now-defunct) blog https://zeppelinleak.wordpress.com (2021-22).

Wider Impact to Date

  • Listed victims ≈ 160 orgs (construction, healthcare, MSP), mainly USA & Europe.
  • Average dwell time: 10 days; this allows lateral movement and data theft – hence patched credentials are crucial before restore.

Bottom Line

EMAN is a Zeppelin offshoot that abuses weak RDP and phishing. Clean recovery today still relies on OFF-LINE BACKUPS; decryption without the criminal-controlled private key is cryptographically infeasible. Harden remote services, back-up immutably, and monitor for the .eman renaming pattern to catch and contain the attack before the final encryption loop completes.