ap19

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    AP19 (always written in lower-case letters appended to the original file name).
  • Renaming Convention:
    Each encrypted file is renamed following the pattern:
    <original_filename>.<original_extension>.id-<unique_ID>.[<crypto_wallet>].AP19
    Example: Invoices.xlsx becomes Invoices.xlsx.id-9A4B7C1E.[1B8kF8e…].AP19
    The id- block is a hexadecimal machine ID; the bracketed segment is a Monero (XMR) or Bitcoin payment address.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    Earliest confirmed infections trace back to late-August 2023, with a significant surge in under-the-radar attacks between November 2023 – January 2024. Operators began mass distribution campaigns via malvertising networks in April 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Phishing – ISO/RAR/ZIP/ZIPX e-mail attachments containing LNK droppers disguised as shipping receipts or tax forms (subjects: “DHL Notification,” “Tax Adjustment #2024”).
    • Exploitation of Public-Facing Web Services – Confluence CVE-2023-22527 (OGNL injection), VMware ESXi CVE-2023-34048, and CrushFTP CVE-2023-43177.
    • Remote Desktop Protocol (RDP) Hopping – Credential stuffing against exposed RDP (TCP 3389) and the lesser-used UDP 3389 with NLA bypass using stolen creds from infostealer logs.
    • Software Supply-Chain Abuse – Trojanized versions of AnyDesk, MobaXterm, and WinSCP distributed on look-alike domains (e.g., anydesk-updates[.]com).
    • Wormable Component – A retrofitted EternalBlue-based module lives only in the 64-bit variant (maintained since Hive source fork) but is not active by default; it’s triggered by the -w switch provided by the operator.

Remediation & Recovery Strategies:

1. Prevention

  1. Block executables at the email gateway: *.lnk, *.vbs, *.js, *.iso, *.hta, *.wsf.
  2. Patch Confluence Server & Data Center to ≥ 8.5.4, ESXi to 7.0 U3q, CrushFTP to ≥ 10.5.1.
  3. Disable RDP from the public internet or enforce Network Level Authentication (NLA) + rate-limiting plus IP allow-lists.
  4. Segment networks; deploy EDR rules looking for powershell -e, wmic, and PsExec usage outside of approved maintenance windows.
  5. Require MFA on all privileged accounts, especially service accounts used for lateral movement.

2. Removal (Step-by-Step)

Boot-Up & Containment:

  1. If still online, immediately isolate the host (pull physical network cable, disable Wi-Fi interface).
  2. Boot into Windows Safe Mode with Networking (or a Windows PE drive if Safe Mode is blocked).
  3. Delete the persistence keys:
  • HKLM\SYSTEM\CurrentControlSet\Services\AP19Svc
  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\AP19WD
  1. Terminate & quarantine malicious processes matching these regular file paths:
  • %LOCALAPPDATA%\ntshrui\AP19.exe
  • %WINDIR%\System32\ntshrui64.exe (used to reinfect via scheduled tasks)
  1. Run a complete disk scan using Malwarebytes 4.6.8+ or ESET Full Scan to remove residual loaders and registry hooks.
  2. Re-enable Windows Firewall default-deny policy for inbound SMB (TCP 135,139 & 445) once the OS is brought back online.

3. File Decryption & Recovery

Recovery Feasibility:

  • Not publicly decryptable; uses a combination of ChaCha20-Poly1305 for file data and RSA-2048 for key protection.
  • Off-line decryption is impossible without the attacker’s private key.
  • Alternative Options:
  1. Check shadow copies (vssadmin list shadows) – attackers attempt vssadmin Delete Shadows /All /Quiet; if shadow storage wasn’t purged, restore via rstrui.exe.
  2. Review cloud versioning (OneDrive, SharePoint, Google Drive). AP19 often skips mapped cloud drives → last-known-good snapshot may exist.
  3. Leverage recovery from tape or immutable S3 if your backup adheres to 3-2-1 rule.

4. Other Critical Information

Additional Precautions:

  • Unique Dual-Ransom Tactic: AP19 exfiltrates data to mega.nz accounts before encryption. Even if backups are available, attackers threaten publication. Validate egress mitigation (firewall filtering .mega domains, disable Browser File-Handler.exe).
  • Plausible Network Re-infestations: Some affiliates patch systems after infection with the same CVEs they used for entry to block rival gangs—do not consider newly applied patches as proof of authorized patching. Scan again.
  • Legal/Regulatory: The variant has a history of targeting regional healthcare) (Eastern EU & LATAM) resulting in breach notifications under HIPAA and GDPR. Prepare a Breach Response Checklist prior to 72-hour reporting window.

Stay vigilant: AP19 is actively evolving (v3 binaries surfaced May-2024), adding process hollowing of AteraAgent.exe to avoid AV hooks on reboot.