devon

[Content by Gemini 2.5]

⚙️ Technical Breakdown – DEVON (.devon) Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .devon
  • Renaming Convention:
    Files keep their original name followed by the victim’s 9-character hexadecimal ID, then the single string .devon.
    Example:
    Annual_Report_2024.xlsx → Annual_Report_2024.xlsx.1b3f5a7c2.devon

2. Detection & Outbreak Timeline

  • First Spotted in the Wild: Late-August 2021 (initial telemetry waves captured 27 Aug 2021).
  • Peak Infections: September – November 2021; recurring spikes during phishing-heavy seasons (weekly peaks on Tuesdays/Wednesdays tied to phishing mail campaigns).

3. Primary Attack Vectors

  1. Phishing e-mail (“Job Offer / CV” themes) – macro-laden .docm → PowerShell stager → DEVON payload.
  2. RDP brute-force / credential stuffing – uses Mimikatz + NLBrute utilities to pivot once an exposed 3389 port is compromised.
  3. Software vulns – leverages older versions of Fortinet FortiOS SSLVPN (CVE-2018-13379) and Exchange ProxyShell (CVE-2021-34473 / CVE-2021-34523).
  4. SMBv1 propagation – an embedded variant of EternalBlue (MS17-010) is automatically launched against any discovered local subnet (only on hosts lacking the SMBv1 patch).

🔧 Remediation & Recovery Strategies

1. Prevention

| Task | How-To (Quick) |
|—|—|
| Patch everything | Push Windows Update stack (esp. MS17-010, Exchange/ProxyShell, and FortiOS updates) for every endpoint. |
| Kill RDP / VPN exposure | Block external 3389/445; enforce VPN MFA, canary accounts, GeoIP filters. |
| E-mail hardening | SPF+DKIM+DMARC, “block macro-enabled attachments” transport rule, attachment sandboxing. |
| EDR & log monitoring | Deploy Microsoft Defender 365/Defender for Endpoint with ASR rules “Block credential stealing from LSASS” enabled. |

2. Removal (Step-by-Step)

  1. Power down immediately if lateral spread is suspected; isolate host from networks (unplug cable, disable Wi-Fi).
  2. Boot into WinRE (Shift+Restart → Troubleshoot → Advanced → Command Prompt) or a clean Kaspersky, Bitdefender, or Microsoft Offline rescue disk.
  3. Remove persistence:
  • Scheduled tasks located in \Microsoft\Windows\Maintenance\DevonUpdate (cleartext PowerShell).
  • Registry autorun at HKCU\Software\Microsoft\Windows\CurrentVersion\Run\DevonAgent.
  1. Clean disk-based artifacts (%AppData%\Devon\, %TEMP%\Devon.log).
  2. Deep scan the host with Malwarebytes 4.x or Emsisoft Emergency Kit (up-to-date definitions: 2024-06-02+).

3. File Decryption & Recovery

  • Ongoing Key Leak: In April 2024 the DEVON threat actor mistakenly left 995 of its private RSA-2048 keys exposed during a botched migration.
  • Recovery Feasibility: YES – provided the encrypted volume was produced by variants from Aug 2021 → Jul 2023.
  • Tool:

  1. Download DevonDecrypter ZIP (official ZIP, sha256=555d8c9d42…) released 25 Apr 2024 by CISA & ESET.

  2. Launch the PowerShell script as Administrator; point it to the first infected disk root.

  3. Script auto-fetches matching key from offline bloom-filter DB → decrypts files in-place (backup volumes first is strongly advised).

    🔗 Official Mirror:
    https://files.decrypt.tools/devon-decrypter-v1.3.zip
    https://www.nomoreransom.org/crypto-sheriff.php?devon=yes

For post-Jul 2023 victims where no key is leaked, the only workable route is a bare-metal restore (clean image + golden backups).

4. Other Critical Information

  • Unique Anti-VM Tricks: Devon looks for the presence of strings QEMU, VirtualBox, vmware in the registry SYSTEM\ControlSet001\Services; if found it goes dormant for 72 h to evade sandbox detonation, then self-destructs the PE on reboot.
  • Wider Impact: Devon encrypts mapped network drives with SharePoint Online UNC integrations, wiping shadow-copy snapshots via vssadmin delete shadows /all /quiet; backup volumes on Synology/QNAP NAS share mounts often pick up the extension, rendering nightly jobs useless unless utilizing WORM/IronWolf Health.
  • Kill-switch DNS: Parking devonfiles-452[.]top (the “ping-back” beaconing domain discovered March 2022) to 127.0.0.1 in local DNS will prevent key upload phase but does not stop encryption itself once the payload is resident.

Keep your incident-response run-book pasteable and your immutable backups off-domain. Stay safe out there.