Hackers Weaponize ChatGPT Custom GPTs in ClickFix Attacks Delivering

🕵️ RESEARCH & DEEP DIVES

• Hackers Weaponize ChatGPT Custom GPTs in ClickFix Attacks Delivering RAT
  Attackers are abusing ChatGPT's Custom GPT feature to trick users into installing a remote access trojan via a ClickFix attack.

  • Targets ChatGPT users on Windows; Huntress investigated at least 40 incidents tied to the campaign's Google Sites infrastructure, including two infections traced to malicious Custom GPTs.
  • A malvertising result leads to a Custom GPT named "Plus 5.6" that shows a fake "Service Availability Notice" redirecting to a Google Sites page posing as a ChatGPT/Cloudflare CAPTCHA check.
  • The ClickFix lure instructs victims to paste and run a PowerShell command that downloads an obfuscated script (server encoded as decimal 1614733393 = 96.62.224[.]81) fetching ISOSimple.msi, installed silently via msiexec.
  • The MSI sideloads a modified ceiinfolog.dll via Canon-signed COTFileReadApp.exe; a later wave swapped in Stardock-signed DeElevate64.exe with loader hidden in a NuGet package named Build.dat.
  • The RAT offers remote desktop, camera/mic capture, file searches, and payload execution, persists via an HKCU Run key and scheduled task named "Canon Configuration Reader", and uses DNS-over-HTTPS via Cloudflare, Google, and Quad9 for C2.
  Sources 📄 Source: huntress.com · 📎 Coverage: cybersecuritynews.com · 👁 via Cyber Security News, cryptika.com (discovered)

• German police use device-linking in WhatsApp, Signal, Telegram to eavesdrop without trojans
  German law enforcement agencies are eavesdropping on encrypted messengers by linking police-controlled devices to suspects' accounts via WhatsApp Web, Signal Desktop, and similar features.

  • Affects users of WhatsApp, Signal, Telegram, and Threema, whose web/desktop clients allow linking a second device to an account.
  • Germany's Customs Office (Zollkriminalamt) has permanently used this technique since August 2025 after a pilot from late 2023, recording messages without cracking encryption or deploying a trojan.
  • Access is gained via physical access to the phone, phishing for in-app verification codes, or intercepting SMS codes through telephone surveillance.
  • Victims can detect linked devices via each app's connected-devices list; BfV and BSI recommend checking and removing unknown devices.
  • Germany's Federal Court of Justice ruled in January 2026 that covert account-cloning constitutes source telecommunications surveillance, and its legal basis remains disputed.
  Sources 📄 Source: netzpolitik.org · 📎 Coverage: schneier.com · 👁 via Schneier on Security

• AgtaBackup RAT hijacks Windows systems via fake Microsoft Store pages and RMM tools
  Palo Alto Networks Unit 42 is tracking a new Windows RAT, AgtaBackup, delivered through fake Microsoft Store pages that install attacker-controlled RMM tools.

  • Targets Windows users via fake Microsoft Store landing pages offering popular video-conferencing software
  • Downloads are actually signed MSI packages for legitimate RMM tools like LogMeIn Resolve or ConnectWise ScreenConnect, enrolling victims into attacker-controlled tenants
  • After a delay of hours or days, operators run PowerShell to silently install the AgtaBackup .NET backdoor, which runs as a hidden SYSTEM service with scheduled tasks that restore it within 60 seconds if removed
  • The RAT checks in every two seconds over WebSocket, enabling command execution, screenshots, hidden desktops, keylogging, and credential theft from nine browsers including Chrome, Edge, Firefox, Brave, Opera, Vivaldi, Chromium, and Yandex
  • C2 domains include avanade[.]cc, bootbackup[.]com, and runtownagtabackup[.]top
  Sources 📄 Source: github.com · 📎 Coverage: cybersecuritynews.com · 👁 via Cyber Security News, cryptika.com (discovered)

📋 ADVISORIES

• Balbooa Forms 2.4.3.4 fixes five Joomla security flaws, several unauthenticated
  Balbooa released Forms 2.4.3.4 fixing five security issues in the Joomla form builder, several reachable without login.
  • Affects Joomla sites running Balbooa Forms (com_baforms) 2.4.3.3, 2.4.3.2, or older; released 29 September 2026.
  • Fixes path traversal via crafted filenames in getFilePath() and email attachment routines, potentially letting anonymous visitors exfiltrate server files like configuration.php via auto-reply attachments.
  • Fixes unauthenticated cross-session deletion of temporary/stored attachments via removeTmpAttachment and cross-session manipulation of attachment references on submit.
  • Fixes stored XSS through uploaded original filenames and display names in admin submission views.
  • Fifth fix hardens the post-submission PHP action against arbitrary code execution via field shortcodes; no CVE or CVSS score assigned yet.
  • Flaws reported by Sergiy Tryzhychynskyi and Łukasz Rybak, with disclosure coordinated by David Jardin of the Joomla Security Strike Team.
  Sources 📎 Coverage: mysites.guru · 👁 via mysites.guru (discovered)

🔓 CVEs & KEV

• CVE-2026-15390 — DENX Software Engineering Das U-Boot — CVSS 9.0 — Out-of-bounds write in Das U-BootDas U-Boot with CONFIG_IP_DEFRAG=y parameter...

• CVE-2026-19547 — Artifex Software Inc. Ghostscript — CVSS 7.0 — Local Privilege Escalation in Ghostscript for WindowsGhostscript for Windows ...