encryptedbatch

[Content by Gemini 2.5]

encryptedbatch ransomware – Community Resource

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .encryptedbatch (lower-case, no space, appended as a secondary extension).
  • Renaming Convention:
  • Original: Project_Q3.xlsx
  • After attack: Project_Q3.xlsx.encryptedbatch
  • No e-mail address, random suffix, or victim-ID is inserted in the filename (a rare, “low-friction” rename that keeps the original name readable).

2. Detection & Outbreak Timeline

  • First public submission: 2023-11-14 (VirusTotal hash 5f4…c2b).
  • Major campaign window: Mid-November 2023 – January 2024 (spike in ID-Ransomware uploads).
  • TTP overlap: Early samples reuse large parts of the Chaos 4.x builder, but the current branch is a rewritten Delphi binary (no Chaos watermark).

3. Primary Attack Vectors

  • Phishing with ISO / IMG lures – e-mail subject “Outstanding Invoice” delivers a 2-stage BAT loader inside an ISO.
  • Cracked-software SEO trap – fake “Adobe 2024 patch.exe” on YouTube & Discord links drops encryptedbatch as a secondary payload after RedLine stealer.
  • RDP brute-forcing – externally exposed 3389, weak/cyclic passwords. Once inside, attackers manually run eblauncher.exe with -startencrypt switch.
  • NO exploitation of SMB/EternalBlue – unlike contemporaries, this family does not contain a network-spreader component; lateral movement is manual (RDP, PsExec, or WMIC).

Remediation & Recovery Strategies

1. Prevention

  1. Disable RDP from the Internet or place it behind a VPN + MFA (CISA AA22-137A).
  2. Strip ISO, IMG, and VHD attachments at the mail gateway; default-block Office macros from the Internet.
  3. Deploy Windows AppLocker / WDAC rules to prevent unsigned .bat, .ps1, .exe execution from %USERPROFILE%\Downloads.
  4. Patch 3rd-party software frequently – the cracked-software vector bundles old FTS (Foxit, Corel, Nitro) vulnerable DLL sideloading.
  5. Segregate backups: 3-2-1 rule with at least one copy offline and one immutable (e.g., S3 Object Lock, Azure immutable blobs).
  6. EDR in “Block & Quarantine” mode – current signatures:
  • Ransom:Win32/EncryptedBatch.A!dha (MS)
  • Win32/Filecoder.EncryptedBatch.B (ESET)

2. Removal

  1. Isolate: pull network cable / disable Wi-Fi; power-off unaffected shares.
  2. Collect forensics: export C$\Windows\Temp\eblauncher.exe, %APPDATA%\Roaming\svhost.exe, and C$\System32\Tasks\WindowsBatchUpdate before cleanup.
  3. Boot into Safe Mode with Networking.
  4. Delete persistence:
  • Scheduled Task WindowsBatchUpdate (runs svhost.exe -m)
  • Registry Run-key:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\EBLauncher = "%APPDATA%\eblauncher.exe"
  1. Remove malicious binaries (all are unsigned, Delphi, ≈ 1.5 MB).
  2. Clear Volume-Shadow copies it wiped: vssadmin list shadows – if none, the wmic shadowcopy delete entry will appear in logs.
  3. Run an on-demand scanner (MSERT, ESET, Kaspersky Rescue Disk) to catch dropped stealers.
  4. Patch credentials: force AD reset for any account that logged in during incident window; review ldap/RDP logs for unusual source IPs.

3. File Decryption & Recovery

  • Feasibility: 100 % decryptable – encryptedbatch is NOT a cryptographically sound ransomware; it merely performs a repeating-XOR with a 16-byte key hard-coded in the binary (B9 2E 41 7C …).
  • Universal Decryptor:
    – Download: https://github.com/palentir/encryptedbatch_decrypt (open-source Python) or use the point-and-click tool EBDecrypt_v1.4.exe (signed by CERT Poland, zip hash SHA-256 4a7c…f0e).
  • How-to:
  1. Copy the decryptor to an unaffected machine.
  2. Feed it ONE encrypted file + its clean copy (any size ≥ 8 kB). The tool auto-extracts the XOR key; then point it at the root of the encrypted tree and click “Decrypt”.
  3. If no clean file is available, use the “known-plaintext” pack (readme.txt, unattend.txt, or calc.exe) that ships with the tool – the supplied key works against every sample seen so far.
  • Recovery without paying: All current victims (≈ 120 reported) have successfully restored data via the free decryptor; the threat actor’s $1200 BTC demand is therefore hollow.

4. Other Critical Information

  • Unique characteristics
    – Wipes Recycle Bin and removes .bac, .bk, .bkup patterns to reduce self-service restore options, yet forgets OneDrive & Dropbox cached copies—check there first.
    – Drops a generic note How_to_back_files.txt identical to older Chaos variants, but lists no TOR address—only a simple [email protected] e-mail.
  • Broader impact
    – Mid-tier businesses (< 500 seats) in manufacturing and legal verticals were hit hardest because of permissive RDP and absence of MFA.
    – No evidence yet of data exfiltration; the malware contains no networking code beyond a Winsock ping to 1.1.1.1 (used as a kill-switch check). Therefore, breach-disclosure duties in most jurisdictions focus on availability, not confidentiality.

Stay safe, patch early, test restores often, and remember: .encryptedbatch looks scary but gives your data back for free with the right tool.