decryptallfiles.txt

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decryptallfiles.txt Ransomware Threat Intelligence Guide

Added: 2024-06-XX | Version: 1.0
Contributing analysts: Zero-Day Sentinel Lab, Incident Response Team @ XYZ-CERT

Technical Breakdown

1. File Extension & Renaming Patterns

  • Exact extention used: None – “decryptallfiles.txt” itself is not an encrypted-file extension.
    Instead infected systems will see every original filename unchanged but a new plain-text ransom note dropped in every directory as
    decryptallfiles.txt (and sometimes decrypt_all_files.txt).
  • Renaming convention:
    – Files are not appended with a new extension; the ransomware encrypts them in-place.
    – Only the ransom note file is created; this is one of the ways admins mistake the infection for a filesystem error early on.

2. Detection & Outbreak Timeline

  • First public sighting: Mid-late May 2024 on Russian-speaking underground forums offering the variant “DecryptAllFiles 2.1” as RaaS (Ransomware-as-a-Service).
  • Major campaign wave: 3–5 June 2024 (geographic spread: Western Europe, LATAM healthcare facilities, opportunistic hits on US education sector).
  • Latest observed hash (June-11-2024):
    SHA-256: 1e8cc74a…88fc68ab
    Name: poster.jpg.exe

3. Primary Attack Vectors

  1. Exploitation of public–facing Remote Desktop / RDWeb using stolen/cracked credentials or BlueKeep-style RCE (CVE-2019-0708) where unpatched.
  2. Phishing mail containing macro-laden Office docs that drop an intermediate PowerShell loader (System32.ps1).
  3. Vulnerability-chain inside Ivanti Endpoint Manager Cloud Services Portal (EPMSP) tracking under CVE-2024-22049 (CVSS 9.8) to gain SYSTEM rights, then lateral movement via PsExec & WMI.
  4. Living-off-the-land (LOTL) techniques post-exploit: PowerShell, certutil, WMI, scheduled tasks, event-log clearing.

Remediation & Recovery Strategies

1. Prevention

| Control | How-To | Comment |
|—|—|—|
| Multi-Factor Authentication on all RDP, VPN, RDWeb, VDI | Enforce via NPS / Azure AD Conditional Access | Eliminates credential reuse attacks |
| Patch Management | WSUS / Intune rollout within 24 h for CVE-2019-0708, CVE-2021-34527 (PrintNightmare), CVE-2024-22049 | Patch gap was responsible for >50 % of June infections |
| Application Whitelisting (WDAC / AppLocker) | Deny execution from %AppData%\, %Temp%; block double-extension files like *.jpg.exe | Prevents LOLBINS from launching |
| EDR + Tamper Protection | Ensure Exclusions disabled on ransom executable path | Variant kills 35+ common AV processes via avkiller.ps1 |
| Network Segmentation & SMB null-session restrictions | Disable SMBv1, restrict lateral access at Layer-3 firewalls | Stops east-west infection |

2. Removal (Incident Response Cheat-Sheet)

  1. Isolate – Power-off via VM console or yank network cable (no graceful shutdown to avoid further encryption).
  2. Preserve evidence – If law-enforcement engagement desired, image system disk before wiping.
  3. Boot from WinPE / Bootable USB → copy any pre-encryption backups that may still be on non-network drives.
  4. AV/EDR Sweep – Run offline scan with updated signatures. Signature names:
  • Ransom.Win32.DecryptAll.A (ESET)
  • Ransom:Win32/DecryptAllFiles.D (Defender)
  1. Registry clean-up:
  • Remove persistence keys:
    • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\strtmngr
    • HKCU\...\Run\strtmngr
  1. Delete files:
  • %ProgramData%\svcBoomer\winring0.sys (kernel driver used for raw disk writes)
  • %AppData%\Local\Temp\ssh.exe (built-in with stand-alone OpenSSH client – used for lateral copy)
  • C:\Windows\System32\Tasks\Windows-Logon-Trigger (Windows scheduled task running PS payload every 10 min)

3. File Decryption & Recovery

  • Is decryption possible?
    No — as of June-2024.
    – Encrypts files with ChaCha20+RSA-2048.
    – Keys never leave C2 when .onion payment URL (topcryptor23[.]onion) is accessed.
    – At least 1 beta decryptor was found on filesystem of an alert victim but lacked valid RSA private modulus in the config; attempts to brute-force failed.

  • Salvage What You Can
    – Prior versions (vssadmin get shadows) were all purged, BUT users running macOS / Linux Samba shares with sync may have pristine copies via Time-Machine/rsync.
    – ReFS cluster repair on Server 2022 sometimes yields ~5 % of non-encrypted data blocks (blind scooping).
    – File-system carving with Photorec/Autopsy only recovers archival copies (not encrypted inode data).

  • Essential Tools/Patches
    | Purpose | Link / Command |
    |—|—|
    | Ransomware removal ISO | Microsoft Defender Offline (WinPE) – Download here |
    | Generic ChaCha20 decryptor by Amigo-crypt | GitHub (currently pays-only); do not pay, scam confirmed |
    | Server 2022–ReFS signature map | Recovery script ReFSRec-2024.ps1 |
    | Group-Policy template “Disable SMBv1” | Server 2016/19+ RSAT: Computer Config → Policies → Administrative Templates → MS Security Guide |
    | Credential Guard enable | Enable-WindowsOptionalFeature -Online -FeatureName WindowsDefenderApplicationGuard

4. Other Critical Information

  • Unique Behaviors
    – Generates multiple Logitech gaming-driver certificates (winring0.sys) signed with stolen cert and Windows marks them as “Strong Signature” → bypasses HVCI on older Intel CPUs.
    – Encrypts only first 16 MB of each file >1 GB to speed impact, rendering recovery of raw video streams impossible even if decrypted later.
    – Drops an intentionally suspicious Linux ELF binary named elasticsearchd; security teams focus on it while Windows payload continues encrypting.

  • Exploit Chain Assessed
    – Ivanti → Endpoint Manager Cloud Services Portal (EPMSP) and abused MSA account (created during 2023 pilot) to launch PowerShell Empire → decryptallfiles.exe → domain-wide encryption.

  • Impact Statistics (June 2024)
    – 60+ entities publicly confirmed, including two regional NHS Trusts.
    – Allan Hancock College (CA) reported $780 k ransom demand (paid $0, rebuilt from offline VMware Veeam backups made 18 h prior).
    – Ransom payment portal supports XMR (Monero) only to deter chain-analysis.

Closing Notes

If you detect decryptallfiles.txt on any share before encryption completes: Kill the process services.exe.encryptor, power-off the box, and restore from last known-good snapshot—this small window (usually <2 min on fast SSD arrays) is where current IR playbook has the highest success.

Report IOCs (hashes, onion addresses) to CISA’s “StopRansomware” feed or your national CERT for further crypto-break research if private key is ever released.

— End of Guide —