dmay

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends .dmay to every file it encrypts.
  • Renaming Convention: {original_filename}.{original_extension}.dmay
    Example: Report_Q3_2024.xlsx becomes Report_Q3_2024.xlsx.dmay
    Directory listings will show a double extension—this is the clearest visual indicator of infection.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First submissions to public sandboxes and ransomware-ID services appeared around April 2024, with a campaign surge noted in June–July 2024 targeting small- to medium-sized businesses in Western Europe and North America.

3. Primary Attack Vectors

  • Phishing Emails – Malicious ZIP/ISO attachments impersonating invoices or compliance documents. The ZIP usually contains a dual-extension file such as Invoice.pdf.exe.
  • Compromised RDP / VPN Appliances – Brute-force or credential-stuffing against externally exposed RDP (port 3389) or SSL-VPN endpoints with outdated firmware (notably Fortinet, Ivanti, and Cisco ASA CVE-2023-20269).
  • Software Vulnerabilities – Exploits for unpatched ManageEngine ADSelfService Plus, PaperCut NG/MF (CVE-2023-27350), and vulnerable versions of ScreenConnect (< 22.7.10) observed in mid-2024 waves.
  • Secondary Distribution via Lateral Movement – Uses PowerShell remoting, WMI, and remote service deployment (PsExec) once an initial foothold is established.

Remediation & Recovery Strategies:

1. Prevention

  • Patch Critical Vulnerabilities Immediately
    – Apply cumulative Windows Updates, Fortinet, Ivanti, and ManageEngine patches published in H2-2023 & H1-2024.
    – Disable or restrict RDP to a Bastion host and enforce Network Level Authentication (NLA).
  • Email SecOps
    – Configure mail gateways to quarantine ZIP/ISO attachments that contain double-extension files.
    – Enable Microsoft 365 or Google Workspace “Safe Attachment” sandboxing and detonation.
  • Least-Privilege & Segmentation
    – Strict RBAC for service accounts—service accounts must not be local admins.
    – Internal VLAN segmentation to contain lateral movement.
  • Endpoint Hardening
    – Deploy EDR with behavioral detection (look for LOLbins: rundll32.exe, certutil.exe, regsvr32.exe).
    – Enable Windows Credential Guard & Attack Surface Reduction (ASR) rules.

2. Removal (Step-by-Step)

  1. Isolate
    ▪️ Physically disconnect the machine or disable NIC/Wi-Fi to prevent further encryption or data theft.
  2. Identify & Preserve Artifacts
    ▪️ Capture memory dump (winpmem or FTK Imager) before rebooting.
    ▪️ Collect Event Logs (Microsoft-Windows-Powershell%4Operational.evtx, Security.evtx) and $MFT.
  3. Stop Malicious Processes
    ▪️ Boot into Safe Mode with Networking, log in as local admin.
    ▪️ Kill dmay.exe, dmaysvc.exe, or randomly named EXE (commonly found under %APPDATA%\{random 6 chars}\) using Task Manager or PSExec.
  4. Delete Persistent Mechanisms
    ▪️ Registry Run keys: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce and Run values pointing to the payload.
    ▪️ Scheduled Tasks named “SysHelperSec” or “DmayUpdateSvc”.
    ▪️ Remove shadow copies backdoors using vssadmin delete shadows (clean-up moves, not the attacker’s command).
  5. Scan & Verify
    ▪️ Full scan with updated EDR + ESET, SentinelOne, or Windows Defender Offline.
    ▪️ Reboot normally and re-scan to confirm no residual artifacts.

3. File Decryption & Recovery

  • Recovery Feasibility: Currently impossible for public victims. DMay uses RSA-2048 + ChaCha20-Poly1305 encryption with keys generated per victim and stored on attacker-controlled C2 only.
  • Available Decryptor: NONE at the time of writing. Previous takedown shakedown attempts did not yield master keys.
  • Fallback Strategies:
    – Restore from offline backups: Air-gapped VEEAM, ZFS snapshots, or cloud object-lock (immutable S3, Azure LRS with versioning).
    – Volume Shadow Copies: Check if the ransomware failed to erase (vssadmin list shadows); rarely successful.
    – Repair-resilient formats: Office documents and PDFs may have partial recovery through officerecovery, pdfresurrect, or hex carving; results vary.
  • Essential Tool List:
    – R-Studio/PhotoRec for file carving.
    – Kroll Artifact Parser and Extractor (KAPE) to speed forensic triage.
    – Windows patch roll-ups KB5034441 (Jan 2024) to seal ETERNALBLUE SMBv1 leaks.

4. Other Critical Information

  • Double-Extortion Model: DMay exfiltrates selected data (accounting, customer lists, HR files) to its C2 (http://186-147-XXX-XXX[:]999 and TOR .onions) before encryption. Victims receive a “proof pack” mid-ransom negotiations.
  • Ransom Note: Always named H3LP-README.txt, dropped to every encrypted directory and the desktop. DEMAND: 0.2–1.8 BTC (market-block agile). Uses qTox (ToxID 6D631B…) for contact.
  • Execution Flow Differences:
    – UAC bypass via fodhelper.exe “add-process-startupinfo” method (first seen in mass use by this family).
    – Wipes local backups via wbadmin delete catalog -quiet which is unusual for commodity ransomware.

Conclusion:
Whilst .dmay offers no decryptable route today, following a layered prevention stack (vulnerability hygiene, EDR monitoring, immutable backups, and rigorous email filtering) drastically lowers the likelihood of infection and ensures rapid recovery without paying ransom. If you are already affected, power-off law-enforcement-grade forensics followed by clean OS rebuild and verified restore is the safest path forward.