Week in review: Actively exploited Windows SMB flaw, trusted OAuth apps turned into cloud backdoors
60
60
60
60
Tracking OceanLotus’ new Downloader, KerrDown
Unit 42 identifies KerrDown, a new OceanLotus (APT32) downloader active since 2018 targeting Vietnamese speakers via malicious macros and DLL side-loading.
Unit 42 tracks KerrDown, a previously undocumented downloader family used by OceanLotus (APT32) since at least early 2018, primarily targeting Vietnam or Vietnamese-speaking individuals. Delivery uses macro-laced Microsoft Office documents embedding base64-encoded 32-bit and 64-bit DLLs, and RAR archives containing a legitimate program abused for DLL side-loading. KerrDown is dropped as main_background.png, downloads a DES-encrypted payload from a URL, and executes it directly in memory. Researchers used Jaccard-index similarity analysis to identify the new family, connect campaign samples, and infer patterns in the group's working hours and days.
52
PAPERMILL Malware Campaign Abuses Signed Notepad++ to Deliver VenomRAT to Windows Users
JUMPSEC tracks PAPERMILL, a China-nexus phishing campaign using a signed Notepad++ binary, libcurl.dll sideloading, and Donut loaders to deploy VenomRAT against Indian tax-audit targets.
PAPERMILL delivers ISO disk images via tax-audit phishing emails that passed SPF, DKIM, and DMARC, containing a renamed Authenticode-signed Notepad++ executable and a malicious libcurl.dll that proxies curl functions while executing loader logic in DllMain. The chain uses Mark-of-the-Web bypasses, anti-sandbox sleeps, UAC elevation prompts, Registry persistence, and a Donut shellcode loader to reflectively load .NET VenomRAT v6.0.3 with HVNC and credential-stealing capability, with C2 at 154.36.188.201:4449. JUMPSEC assesses the campaign as China-nexus, financially motivated, and Silver Fox-adjacent rather than definitively Silver Fox-operated.
55
Malicious Twitch Browser Extension Leaks OAuth Tokens From Nearly 31,000 Users
Malicious Twitch extension 'Twitch Enhanced Viewer | JeetBot' leaked OAuth tokens from nearly 31,000 users to Russian bot-service proxy servers.
Socket researchers found the 'Twitch Enhanced Viewer | JeetBot' browser extension forwarded users' live Twitch OAuth tokens as an &auth= query parameter to operator-controlled proxy servers, affecting about 30,000 Chrome users and 604 Firefox users. The tokens, written in cleartext to proxy logs, are bearer credentials granting access to chat, whispers, and account settings without password or 2FA. The operator is a Russian commercial Twitch/Kick/VK-Live bot SaaS linked to Cyprus-based developer Aleksandr Popov; earlier v4.x builds also POSTed tokens to a set-token endpoint. Firefox add-on version 85.8.7 stops the token forwarding, but previously transmitted tokens remain valid until revoked.
50
60
60
57
60
Four REVSTEALER-Linked Modules Disable Windows Update and Defender to Run a Crypto Miner
Elastic documents four persistent REVSTEALER-linked tools (ProManager, WinUpdate, SoftManager, LockAppHost); LockAppHost disables Windows Update and Defender to run a crypto miner.
Elastic Security Labs identified four previously unreported executables tied to REVSTEALER, a commercial Windows infostealer sold since at least February 2026: ProManager, WinUpdate, SoftManager, and LockAppHost. LockAppHost abuses CMSTP for elevation, adds Microsoft Defender exclusions, disables five Windows Update services and 13 scheduled tasks, then hides a miner in legitimate Windows processes; other modules steal wallets, clipboard-swap crypto addresses, and turn victims into reverse proxies. The components share REVSTEALER tradecraft including packer, runtime function resolution, and Polygon smart-contract backup configuration (EtherHiding). Elastic's detection rule matched about 4,700 VirusTotal samples over the past year; distribution uses hijacked YouTube channels promoting game cheats and a fake 'Claude Opus 5 Free Desktop' app.
45
57
ClearFake WebDAV infection chain delivers Amatera stealer, ZigCryptoStealer, and NetSupport Manager
Cisco Talos details ClearFake WebDAV chains delivering Amatera stealer to a Ukrainian government organization, with cryptocurrency and credential theft payloads.
Cisco Talos investigated DLL executions named 'verification.google' via WebDAV UNC paths at a Ukrainian government organization, tracking the actor as UAT-10820 and assessing with moderate confidence the activity is Russian and opportunistic rather than targeted. The infection chain uses ClearFake JavaScript injected via a Cloudflare Worker, EtherHiding storage on BNB Smart Chain contracts, and a ClickFix fake Google CAPTCHA prompt to deliver Amatera stealer. Secondary payloads differ by C2: one loader deploys ZigCryptoStealer with a Go reverse TCP proxy and a vulnerable driver that kills EDR, while the other installs an unauthorized NetSupport Manager with a Russia-based C2. Similar Amatera chains were separately documented by Malwarebytes and Blackpoint Cyber, but with no shared infrastructure.
55
Muhstik Botnet Attacks Tomato Routers to Harvest New IoT Devices
Unit 42 found a Muhstik botnet variant brute-forcing Tomato router web authentication to harvest IoT devices for crypto mining and DDoS attacks.
Palo Alto Networks Unit 42 researchers in December 2019 identified a new Muhstik botnet variant scanning Tomato routers on TCP 8080 and brute-forcing default admin credentials, targeting roughly 4,600 exposed devices found via Shodan. The variant also scans WordPress and Webuzo installations and exploits the Oracle WebLogic deserialization flaw CVE-2019-2725 for unauthenticated remote code execution. Muhstik, active since March 2018, self-propagates like a worm and typically monetizes infections through cryptocurrency mining and DDoS attacks controlled via an IRC C2 channel.
32
60
60
60
Hackers Abuse YouTube Gaming Channels and SEO Poisoning to Deploy RATs and Chrome Hijacker
Unit 42 exposed CL-CRI-1171, a pay-per-install operation using YouTube gaming channels and SEO poisoning to deliver RATs and a Chrome hijacker.
Palo Alto Networks Unit 42 identified over 10,000 OfferLoader samples and 11 YouTube channels pushing trojanized installers via gaming lures and SEO-poisoned searches for tools like WinDirStat and Bluetooth drivers. Trojanized Inno Setup installers spawn three payload branches: Insomnia RAT (dual Node.js/Python backdoor that disables Microsoft Defender), ARKTunnel (undocumented RAT hiding its payload in a bitmap image and tunneling TCP/UDP), and Docro Hijacker (alters Chrome protected preferences to hijack search and affiliate links). The pay-per-install model sells each infection to multiple buyers, reaching gamers as well as corporate and government endpoints.
55
60
60
Week in review: AiTM phishing kit used to hijack AWS accounts, year-long malware campaign targets HR
60