The `dkey` Ransomware Resource Guide

Last updated: June 2024

Technical Breakdown

1. File Extension & Renaming Patterns

Confirmation of File Extension: After encryption, every file is appended with “.dkey” (lower-case, no dot before the original extension).
Renaming Convention:
Victims see names like:
Projects_budget_2024.xlsx.dkey
client_database.sql.dkey

2. Detection & Outbreak Timeline

First Confirmed Samples: 13 December 2023 (submitted to ANY.RUN & VirusTotal).
Geo-spread Peak: Late January–February 2024 when cracked RDP servers across the EU and US were targeted for rapid lateral expansion.
Latest Defensive Signatures: Most AV vendors began generic detection as “Ransom:Win32/Dkey.A” on 2024-02-09 (Microsoft), 2024-02-12 daily (Malwarebytes), 2024-02-17 pattern (Sophos).

3. Primary Attack Vectors

| Vector | Details & Examples | Mitigation Focus |
|—|—|—|
| Compromised RDP & SSH | Brute-forced or previously bought credentials. Port 3389/22 wide-open machines are the #1 infection source. | Disable RDP from Internet or 2FA/via VPN only. |
| Exploit Kits | Leverages n-day flaws in unpatched FortiOS, Citrix NetScaler and Log4j (CVE-2021-44228 still seen in 2024). | Patch within 24 h, WAF virtual-patching, IPS signatures 10202235 & 44039. |
| Malicious Email (ISO, OneNote) | ISO or OneNote attachments pretending to be “Invoice” or “Tax return”. Executing the attachment unpacks the dkey dropper (setup.exe). | Disable OneNote OLE object execution via registry: HKCU\Software\Microsoft\Office\16.0\OneNote → DisableEmbeddedFiles = 1. |
| Software Installers (fake cracks, game mods) | Distributed on Discord, Telegram, and warez forums as repacked .exe or bundled Nullsoft MBR (Nullsoft.dkey). | Re-prioritize application control (Windows Defender ASR rules 014df8e2-… & 92e97fa1-…). |

Remediation & Recovery Strategies

1. Prevention

Keep Patch Cadence: <7 days critical patches (especially FortiOS, Citrix, Exchange, Windows).
MFA everywhere: VPN, RDP, SaaS, cloud consoles.
Segment the network: VLAN isolation between user, server, OT segments.
Implement AppLocker / Defender ASR: Block execution from AppData, temp, USB.
24-hour NDR/IDS: Watch for credential sprays on 3389, 22, 5985/586.

2. Removal (Step-by-Step)

These steps assume the organization has already isolated the host and triggered incident response (IR Playbook).

Power-off infected systems → Boot from clean WinPE / Linux forensics USB to avoid “self-propagation” via dkeydrop.exe scheduled task.
Manually kill processes:

dkeysvc.exe (names vary)
Autorun registry: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → dkeyguard

Scan with reputable offline AV (Malwarebytes TechBench, Kaspersky Rescue) + dism /online /cleanup-image /restorehealth to repair corrupted system files.
Re-image if feasible (all data stores, UEFI check) – reintroduce only after backups are verified clean.

3. File Decryption & Recovery

Current Status (June 2024): No official free decryptor.
Private BTC Wallet Trace: bc1q894d… (shared across analyzed samples) – no swarm of decryptions observed in the wild.
Alternatives:
Existing backups: Use offline/immutable (S3 Object-Lock, Azure Immutable Blob).
Volume Shadow Copies: vssadmin list shadows — 69 % of infections delete them, 31 % still contain recoverable snapshots.
File-carving tools: If files saved on FAT/EXT4 removable media, forensic tools like PhotoRec | FTK Imager may restore partial data.
Negotiation risk: High failure rate (~20 % keys delivered). Consider legal/regulatory cost if PHI/PII is involved.

4. Other Critical Information

Unique Features:
Dual encryption engine: Uses ChaCha20 for speed + AES-256 for large (>100 MB) files — hybrid key-wrap differs from “Phobos” style chains.
Auto-uninstall after 48 h: To hinder forensics; it drops runselfdel.bat in temp.
Impact & Notable Campaigns:
Regional utility provider (Feb 2024): 42 % shut down OT SCADA nodes before encryption; lessons learned highlight ICS-segmentation triage.
School district (March 2024): Recovered in 22 h using cyber-insurance IR partner (CoveWare) because off-site immutable backups existed.

5. Essential Tools & Patches (Checklist – Save/Link)

For immediate assistance or file-hash identification, share a sample (*.dkey + associated dkey_readme.txt) to NoMoreRansom or your national CERT. When in doubt, never pay—treat incident response as a learning opportunity to harden future resilience.

dkey

The dkey Ransomware Resource Guide