Mustang Panda Adds Signed Windows Rootkit to CoolClient Backdoor for Stealth
Kaspersky reports Mustang Panda's updated CoolClient backdoor now deploys a signed kernel-mode Windows rootkit, hitting government victims in Myanmar, Mongolia, Pakistan, and Russia.
Kaspersky identified a new CoolClient variant attributed to HoneyMyte (Mustang Panda) that installs a digitally signed Windows kernel driver, msagent.sys, to hide and protect malicious processes, files, registry keys, and C2 network information. CoolClient is consistently deployed as a secondary backdoor after PlugX, with confirmed victims including government entities in Myanmar, Mongolia, Pakistan, and Russia. In a Myanmar campaign, PlugX was used to deploy CoolClient via a renamed Sangfor executable for DLL side-loading, a scheduled task for persistence, and RPC-based process creation with PPID spoofing. The driver, signed with a 2013 certificate issued to Nanjing Ranyi Technology, implements 33 IOCTL handlers, process hiding via unlinking, a filesystem minifilter, and registry callbacks.
Stealth rootkit targeting F5 BIG-IP could expose enterprise identity gateways
Sophos analyzed a stealth Linux rootkit that hides a web shell in memory on compromised F5 BIG-IP APM identity gateways, evading file-based detection.
Sophos analyzed a second-stage Linux rootkit implant found in compromised F5 BIG-IP APM environments running Apache and PHP, linked to exploitation of CVE-2025-53521, an unauthenticated RCE. The implant hooks Apache's PHP-loading process and serves modified in-memory versions of three legitimate webtop PHP files (apm_css.php3, full_wt.php3, webtop_popup_css.php3), leaving on-disk files untouched so hashes and integrity checks pass. It also establishes access via an authenticated local UNIX socket that can provide an interactive /bin/bash session. Experts warn compromised APM appliances, which handle federated SSO and terminate TLS at enterprise perimeters, could enable SSO token theft and lateral movement to trusted downstream applications.
New Mirai variant adds stealth capabilities to notorious botnet code
FortiGuard Labs reports new Mirai-derived botnet Evooo1Bot actively exploits unpatched routers and edge devices, adding encrypted C2, stealthy SSH scanning, and proxying.
FortiGuard Labs has identified Evooo1Bot, a previously undocumented Linux malware based on the Mirai botnet code, which has been actively exploiting unpatched vulnerabilities in internet-facing hardware for at least a month. Targeted devices include routers and edge hardware from Alcatel, D-Link, Mitsubishi Electric, Netgear, Tenda and Telesquare, with telemetry showing activity in North and South America, Europe, India, China and Japan. Beyond Mirai's usual DDoS functions, the variant adds encrypted C2 communications, a honeypot-aware SSH scanner, a sniffer for unchanged default credentials, and abuse of the SOCKS protocol to turn compromised devices into persistent proxies for concealing origin and pivoting into internal networks.
New Phishing Attack Creates Malicious Pages Inside the Victim’s Browser
Barracuda details a phishing campaign that renders pages in-browser via blob URLs, routed through Microsoft Teams and cdn.bloom[.]io to evade detection.
Barracuda researchers analyzed a phishing campaign that generates a blob URL to render the phishing page entirely inside the victim's browser, leaving no static page for scanners to inspect. The chain begins with a Docusign-themed email containing a calendar invite, followed by a crafted redirect through Microsoft Teams to a resource on cdn.bloom[.]io that the browser converts into the blob URL. Service workers, iframes, and a hidden command-and-control configuration indicate the page is part of a centrally managed phishing platform that can be updated and steered across victims. Researchers recommend inspecting blob URL activity, monitoring OAuth authorization flows, and analyzing the full click path in email security controls.
Inside Knight Office, a New M365 AiTM Phishing Kit
Huntress details Knight Office, a new AiTM phishing kit stealing Microsoft 365 session tokens and registering attacker-controlled devices.
Huntress investigated an August 18, 2026 adversary-in-the-middle attack using the Knight Office phishing kit, which captured Microsoft 365 session tokens via a DocuSign-style lure routed through a Monday.com tracking link and a compromised Joomla site. After token capture, the actor enrolled an unauthorized host in Microsoft Entra ID and bound a Windows Hello for Business key credential to the account. The kit's operator console, found at IP 104.37.188.94, is built on Python Flask and hosts at least 25 .vu phishing domains. Telemetry links the kit to at least nine token-replay logins in two weeks and roughly 700 reported lure emails since April.
Operation QUICSILVER Targets Myanmar Government and IT with QUICAgent Backdoor
Seqrite Labs details Operation QUICSILVER, a China-nexus espionage campaign targeting Myanmar government and IT with graduation-invite lures deploying QUICAgent backdoor.
Seqrite Labs reported Operation QUICSILVER, a cyber espionage campaign against Myanmar's government and IT sectors attributed with moderate confidence to a China-nexus actor. Since April 2026, attacks used fake Belgian-Myanmar holiday and Burmese graduation ceremony invitation lures delivered via VHD/LNK files that abuse ftp.exe (LOLBAS) to assemble and launch QUICAgent, a Go backdoor communicating over QUIC on UDP 443 with five commands and Startup-folder persistence. Separately, China-linked Mustang Panda was observed using an updated COOLCLIENT backdoor with a signed kernel-mode driver across Myanmar, Mongolia, Pakistan, and Russia.
Lazarus Used Post-Quantum Key Exchange to Deliver Zero-Day
Lazarus used a post-quantum key exchange to shield delivery of a Windows zero-day exploit, adding stealth to its campaign.
North Korean Lazarus Group malware used a post-quantum key exchange to protect the delivery of a Windows zero-day exploit. The technique adds a layer of stealth to the campaign's initial access, complicating detection and traffic inspection. It signals growing APT adoption of post-quantum cryptography in offensive operations.
When scanners miss the attack: how Cloudflare Client-Side Security protects storefronts
Cloudflare's Page Shield ML uncovered four malicious JavaScript campaigns on storefronts, including affiliate fraud and a remote-backdoor script, that VirusTotal and URLScan missed.
Cloudflare's Page Shield ML detected four client-side JavaScript operations (eight payloads) in live traffic on online storefronts, enabling affiliate commission hijacking, clickless affiliate theft via hidden iframes, user tracking with a remote-code backdoor, and cloaking of paid mobile visitors. Seven of the eight payloads were absent from VirusTotal and URLScan returned no malicious verdict for any, including a Lnkr-family payload indexed unclassified for roughly 2.5 years. Detection relies on a graph neural network over JavaScript syntax trees, an LLM second opinion on Workers AI, and a frontier-model ensemble voting across benign, magecart, other malware, and cryptomining labels.
China-Linked Hackers Chain Chrome Zero-Day With Windows Kernel Flaw in Attacks
Volexity reports China-linked UTA0560 and JungleBamboo chained Chrome zero-day CVE-2026-85046 with kernel flaws to spy on NGOs.
Volexity documented campaigns detected on September 1, 2026, in which China-linked actors UTA0560 and JungleBamboo (APT31) chained CVE-2026-85046 (V8 type confusion), CVE-2026-87491 (WebAssembly sandbox escape), and CVE-2026-85880 (Windows kernel privilege escalation in RtlpCreateServerAcl). Victims were lured via links on legitimate U.S. university sites vulnerable to reflected XSS, then served hidden exploit iframes behind a donation-form image. Although a V8 fix had landed in Chromium's source after private August reporting, Chrome had not yet shipped it, creating a patch gap the actors exploited. The two groups installed distinct payloads: UTA0560 delivered the GRIMWEDGE JScript backdoor via DLL side-loading, while JungleBamboo used the SUPERSTOMP loader to install the LONGTALE credential-stealing Chrome extension disguised as Google Gemini.
Russian State-Sponsored Hackers Use Claude to Rebuild Malware After Detection
Anthropic disrupted APT29-linked GTG-20006, which used Claude to autonomously rebuild malware, hijack hotel Wi-Fi DNS, and target 20-plus Ukrainian, European, and US-linked organizations.
Anthropic attributed the campaign to GTG-20006, aligned with Midnight Blizzard (APT29/Cozy Bear), which developed an AI-driven process that monitors its implants against security products and autonomously rebuilds and redeploys detected malware. Targets included military intelligence, diplomatic, and defense organizations in Ukraine and Europe, plus Middle East and Asian maritime agencies; the actor compromised at least three hotel Wi-Fi vendors via DNS hijacking and served ClickFix lures delivering Windows, Android, and iOS malware such as PowerChrome, GiftDrop, and DarkSword. Operations also included a North African breach exfiltrating over 300,000 national identity records and 500,000-plus company registry entries, an Embassy Kit device-code phishing campaign stealing Microsoft 365 tokens from at least eight organizations, and WhatsApp account takeover using headless browsers. The campaign overlaps with CaptiveCrunch reporting from ReliaQuest, Microsoft, Google, and Lumen Black Lotus Labs.
Four groups caught using the same Chrome and Windows exploit kit
Proofpoint reports at least four hacking groups, some China-linked, share the BlueMoon exploit kit chaining Chromium and Windows kernel vulnerabilities to install malware.
Proofpoint named the nearly identical kit BlueMoon; it chains two Chromium vulnerabilities with one Windows kernel privilege-escalation flaw affecting Windows 10 (October 2018 Update and 2004), Windows Server 2019 and 2022, and the initial Windows 11 release. All three vulnerabilities received patches within 24 hours of the activity. The kit is being actively used by at least four hacking groups, some with Chinese government ties. Proofpoint links the rapid, visible sharing of a historically rare full browser exploit chain to the Chromium supply-chain patch gap and AI-assisted exploit development.
4 groups caught using the same Chrome and Windows exploit kit
Proofpoint says at least four groups, some China-linked, actively share the BlueMoon kit chaining two Chromium and one Windows kernel exploit.
Proofpoint researchers report that at least four hacking groups, some with ties to the Chinese government, are actively using a nearly identical exploit kit named BlueMoon. The kit chains two Chromium browser vulnerabilities and one Windows kernel flaw affecting Windows 10, Windows 11 initial release, and a later Windows version to install malware of the attacker's choice. All three vulnerabilities received patches within the past 24 hours. Proofpoint attributes the kit's rapid, widely shared deployment to a Chromium patch-gap window and AI agents accelerating exploit development against publicly accessible upstream patches.
Hackers Chain Chrome and Windows Zero-Days in New BlueMoon Exploit Kit Attacks
Multiple espionage actors, mostly China-nexus, are chaining Chrome V8 and Windows kernel zero-days (CVE-2026-85046, CVE-2026-85880) via the BlueMoon exploit kit against government and defense targets.
Proofpoint identified a new exploit kit dubbed BlueMoon chaining a Chromium V8 type-confusion RCE (CVE-2026-85046), a V8 sandbox escape, and a Windows kernel LPE (CVE-2026-85880). At least four distinct threat clusters, most with suspected China nexus, adopted the kit within days starting with TA412 (Violet Typhoon/APT31) on August 28, 2026. Both Chrome-side flaws were patch-gap zero-days with roughly a four-week exploitation window; the Windows LPE only works on Windows 10 and Server 2019/2022. TA412 used spearphishing posing as university interns to deliver the GemStone browser backdoor disguised as a Google Gemini extension; other clusters delivered ShadowPad via DLL sideloading and a Rust loader against targets in aerospace, government, and finance.
HVNC Backdoor Targets LATAM Organizations with Fake Tax and DocuSign Lures
A custom HVNC backdoor is targeting Latin American financial organizations via fake DocuSign and NFe tax-document lures, giving attackers hidden persistent remote access.
ANY.RUN researchers analyzed a multi-stage phishing campaign delivering a custom HVNC backdoor to banking and financial organizations in Latin America. The chain starts with fake DocuSign and NFe tax-document pages that serve per-visitor ZIP archives, followed by an LNK dropper, an NSIS loader, and a 64-bit backdoor masquerading as Windows Update Assistant. The implant provides hidden remote desktop control, keystroke monitoring, Firefox data theft, Startup-folder persistence, and EDR-aware behavior, communicating over TCP/27015.
AI Coding Agents Are Installing Unknown/Untrusted Code on Corporate Networks
Researchers found 120 corporate llms.txt files pointing to unregistered packages, demonstrating AI coding agents install and execute attacker-controlled code on Fortune 500 networks.
Researchers at an Israeli stealth startup scanned 6,214 live domains belonging to defense contractors, Fortune 500 and Big Tech companies, finding 120 llms.txt files that pointed to unregistered code packages or domain names. After registering a handful of the unclaimed names, they received a phone-home beacon within an hour from a Fortune 500 company and dozens more over time. Parent-process chains showed coding agents including Claude, OpenAI's Codex and Nous Research's Hermes executed the installed packages. The researchers warn agents treating vendor docs as ground truth creates a SolarWinds-style supply-chain surface as agent adoption spreads across SaaS, cloud and endpoints.
ThreatsDay: CEO Phishing Kits, 5K Dropbox Account Hacks, OAuth Traps + 17 More Stories
Microsoft warns of Teams IT-impersonation intrusions deploying Node.js implants; Spring Ring vishing hit 150+ employees across 10 companies; The Gentlemen ransomware claims 683 victims.
Microsoft warned of a human-operated campaign abusing Teams external collaboration to impersonate IT help desk staff, deploy malicious MSI packages staging Node.js runtimes and obfuscated JavaScript implants, then pivot to domain controllers over WinRM. Unit 42 documented the Spring Ring vishing operation targeting over 150 employees across at least 10 companies using 26 attacker identities, including an NTLM relay variant against domain controllers. Sophos reported The Gentlemen ransomware (Gold Sherwood) reached 683 total victims by end of July 2026, adding 169 in July, with a playbook using BYOVD-based EDR killers and backup tampering. Group-IB found the Outsider phishing-as-a-service platform created 700+ new phishing pages within a month despite law enforcement takedowns.
BraZetsu Malware Turns Compromised Windows Hosts Into Criminal Marketplace Inventory
Group-IB details BraZetsu, a modular Python Windows malware that monetizes compromised-host access through the Infected Marketplace for initial access brokers.
Group-IB attributes BraZetsu to the Exilware threat actor, believed to be native Portuguese speakers targeting Iberian and Latin American e-commerce, financial, industrial, and law enforcement victims. The framework, first observed in early May 2026, uses generative AI for data triage and target prioritization, steals browser histories and digital certificates, and hunts Brazilian CNAB financial remittance files. Access to compromised hosts is sold on the Infected Marketplace from roughly $5.80, letting buyers remotely deploy secondary payloads over WebSocket-linked infrastructure. Some samples evaded detection on VirusTotal; delivery likely uses VBS loaders from a domain also used to distribute the Ousaban banking trojan.