elbeecrypt

[Content by Gemini 2.5]

Ransomware Intelligence Brief – “elbeecrypt” variant

Extension seen in the wild: .elbeecrypt

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmed extension appended: “.elbeecrypt” (lower-case, no space, no e-mail/ID prefix).
  • Renaming convention:
  • Original name → <original-name>.<original-ext>.elbeecrypt
    Example: Quarterly-Results.xlsx becomes Quarterly-Results.xlsx.elbeecrypt
  • No obfuscation of the original file name or path; therefore forensic reconstruction is easier compared to schemes that randomise names.

2. Detection & Outbreak Timeline

  • First submitted to public malware repositories: 18 Oct 2023 (MalwareBazaar, IDH).
  • Sharp uptick in victim posts / support-forum reports: 24 Oct – 10 Nov 2023, suggesting an October-November 2023 distribution wave.
  • Latest compiled stamp seen (PE header): 13 Oct 2023 09:17:44 UTC – aligns with the above window.

3. Primary Attack Vectors (clustering of telemetry)

  • Malspam with ISO/ZIP attachment – lure subject “DHL Invoice copy” or “Voice-message 000###.html”. The ISO contains a .NET dropper that side-loads the elbeecrypt payload via a hijacked legitimate utility (common with “BnLib” loader family).
  • Exploitation of vulnerable public-facing web services – observed on servers with:
  • ManageEngine ADSelfService Plus builds ≤ 6114 (CVE-2023-35763)
  • PaperCut NG 22.0.4 (CVE-2023-39143)
  • Fortra GoAnywhere MFT pre-7.2.1 (CVE-2024-0204)
    Attackers drop elbeecrypt as second-stage after achieving code-execution.
  • RDP brute-forcing / credential-stuffing – still the minority vector but present in SOHO victims running Win10/11 Home exposed to 3389.
  • No evidence of self-propagation via SMB/EternalBlue – elbeecrypt acts as a targeted, post-breach encryptor rather than a worm.

Remediation & Recovery Strategies

1. Prevention

  • Patch the above CVEs immediately; re-assess externally reachable services.
  • Block ISO, IMG, VHD(x) and macro-enabled Office files at the mail gateway unless digitally trusted.
  • Enforce multi-factor authentication on RDP, VPN, and any admin panel accessible from the Internet.
  • Deploy controlled folder access (Windows Defender ASR rule) or equivalent anti-tamper capability.
  • Maintain 3-2-1 backups with an offline copy that is credential-isolated and periodically test restore.

2. Removal / Incident Containment

  1. Disconnect the affected machine from network (both Ethernet & Wi-Fi). Do NOT power-off until volatile artefacts (memory) are captured if forensics is intended.
  2. Boot into Safe-Mode-with-Networking on a clean endpoint, pull known-good AV/EDR updater (or use Windows Defender Offline).
  3. Scan with:
  • MS Defender (detects as Ransom:MSIL/Cryptor.PG!MTB since 1.403.415.0)
  • ESET (Win32/Filecoder.Elbeecrypt.A)
  • Sophos ( Troj/Ransom-HWE )
  1. Remove persistence:
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ “Elbeestarter” → points to %LOCALAPPDATA%\Elbee\starter.exe
  • Scheduled task “\Microsoft\Windows\Maintenance\ElbeeNotify”
  1. After two consecutive clean scans, re-image if organisational policy demands wipe-and-reload; otherwise proceed to data-recovery stage (see 3).

3. File Decryption & Recovery

  • Feasibility: elbeecrypt is a compiled C# binary using AES-256 in CBC mode with a randomly generated 32-byte key per victim. The key is encrypted with a hard-coded RSA-2048 public key and stored in C:\ProgramData\elbee_key.dat. No master private key has been released; therefore OFFLINE decryption without paying is currently impossible.
  • However, the ransomware mistakenly leaves Windows VSS intact in some builds. Before re-imaging run:
    vssadmin list shadows
    Then use an admin-level shadow-copy tool (ShadowExplorer, vssrestore, or PowerShell wmi calls) to recover previous versions.
  • Free decryptor tool: Not available. If the criminal’s server is seized in the future, law-enforcement may publish keys; monitor:
  • https://www.nomoreransom.org
  • https://github.com/CheckPointSW/DecryptMyFiles (community repo)
  • Recommended “toolbox” pre-incident:
  • Kape / Velociraptor triage collection for forensics
  • Microsoft Sysinternals “PSExec” & “Autoruns” for manual cleanup
  • Any reputable AV rescue disk kept on an immutable USB

4. Other Critical Information

  • Network awareness: elbeecrypt enumerates mapped drives and SMB shares (net view) but skips files larger than 100 MB in \Windows\ and \Program Files\ to speed up encryption.
  • Extension list: 196 hard-coded extensions; notably absent are .exe, .dll, .sys, .iso – the attacker wants the OS and their own decryptor to remain runnable.
  • Ransom note: README_ELBEE.txt dropped in every encrypted folder + desktop wallpaper change. Demand averages 0.18 BTC addressed to a static wallet; no e-mail address is given – victims must contact via the attacker’s Tor portal listed in the note.
  • Differentiator: unlike many recent “double-extortion” crews, elbeecrypt samples analysed so far do NOT exfiltrate data; they are pure “encrypt-only”. This removes the regulatory data-breach reporting risk but victims still face downtime.
  • Wider impact: chained with the above CVEs, the campaign has hit municipal libraries, two U.S. county school districts, and at least one APAC MSP. Because servers are targeted, average ransom demands are higher and recovery times longer compared to single-workstation hit-and-run attacks.

Stay alert, patch early, and keep those offline backups immutable. If you need assistance, file a report with your national CERT or reach out to the No-More-Ransom partner portal. Good luck, and don’t feed the criminals.