[eset]

October 31, 2026

• Nextron detailed two espionage chains against Arabic-speaking government, HR, diplomatic, student and NGO targets, built from fourteen files collected May–August 2026. Chain one: a macro document with reversed strings fetches an HTA over WMI, which strips the Zone.Identifier from an Arabic questionnaire decoy and XOR-extracts a Go backdoor from a PNG (key byte read from the image), persisting as Run value HostHelpLoader and beaconing to mmarketplaces[.]com. Chain two delivers a C++ libcurl implant inside a 200 MiB VHDX so the payload never receives Mark-of-the-Web, persisting via a Startup .lnk — or a scheduled task when Kaspersky is present — and skipping persistence entirely when it finds no AV. One sample is ESET's Arid Gopher (Arid Viper/APT-C-23) with high confidence; the two campaigns match no published indicator, so attribution there is moderate (Nextron). · Threat Intelligence

in Open-Weight Model Turns Firefox's Patch Gap Into Working Exploits

October 25, 2026

• Sandworm and UAC-0099 teamed up for a destructive wiper attack on a Ukrainian logistics company, with UAC-0099 (aka Earth Sirrush) gaining initial access on July 16, 2025 via a spear-phishing attachment, per ESET. The intrusion involved a previously undocumented mesh-network backdoor. (The Hacker News) · Threat Activity

in When the Red Team Is the Model: OpenAI's Agents Escaped Their Own Sandbox

October 23, 2026

• MythicRatatoskr hides its C2 inside the Yggdrasil mesh network. ESET documents a previously unreported Go backdoor used against a Ukrainian grain logistics firm: UAC-0099 gained initial access on July 16, 2025 and handed it to Sandworm, which ran a data-wiping attack on September 17, 2025. ESET · Threat Activity

in Two Unpatched KSMBD RCEs Go Public — and an AI Scanner Found Them

September 18, 2026

• FamousSparrow has replaced SparrowDoor with a new flagship backdoor, SparroWocky, in a campaign ESET has tracked since at least August 2025 against government bodies in seven Latin American countries — Guatemala, Honduras, Puerto Rico, Panama, Venezuela, Peru and Argentina. The backdoor is heavily anti-analysis, borrows from open-source projects, and supports file exfiltration, screenshots and host recon; ESET notes one Panamanian victim is directly involved in the canal ports dispute, and the group has been publicly linked to Salt Typhoon (ESET, The Record). · Threat Activity

in Plugin4Shell Turns Pinned Agent Plugins Into Zero-Click RCE

September 2, 2026

• UAC-0099 is weaponising LLM safety filters as an anti-analysis technique. ESET's GuardBreaker write-up describes the Russia-aligned actor embedding nuclear-weapons-themed content in malware to deliberately trip refusal behaviour and block AI-assisted reverse engineering of samples (The Hacker News). Follows the same actor's activity noted last week (earlier coverage). · AI & Model Security

in OpenAI Says Astra Crossed the Line: Autonomous Zero-Day Discovery at "Critical" Cyber Risk

August 29, 2026

• ESET documented GuardBreaker, an anti-EDR technique used by Russia-aligned UAC-0099 against a Ukrainian victim (@thegrugq), continuing a busy week for the group (earlier coverage). Separate analysis traces a UAC-0099 WSF lure through a LUNCHPOKE → BURNYBEAR → MATCHBOIL.V2 chain with claimed overlap into Sandworm activity (chain analysis). · Threat Activity

in PaperCut Ships a Second Emergency Patch After Researchers Bypass the First

August 28, 2026

• UAC-0099 is deliberately tripping LLM safety filters to block malware analysis. ESET documented GuardBreaker, used against a Ukrainian victim: the operators pad a malicious VBS downloader with a comment asking for help building a nuclear weapon, so an AI-assisted analysis pipeline refuses and never reaches the actual MATCHBOIL installer logic (ESET Research). Anyone running LLM triage in a malware workflow should assume this is now standard tradecraft. · AI & Model Security

in Australia Charges Two Over the TeamPCP Supply-Chain Spree

August 21, 2026

• PussyBlocker-UndefendV2 — a security-update disruption tool targeting the signature-refresh paths of Defender, Windows Update, Kaspersky and ESET; a reminder that update starvation is a quiet detection gap worth alerting on (GitHub, background post). · New Tools & Releases

in Microsoft's Own Defender Driver Becomes the EDR Killer

July 31, 2026

• ESET analyzed 900,000 agentic AI "skills" (task add-ons for AI agents) in H1 2026 and flagged 25,000 as suspicious and more than 3,000 as outright malicious — including one that built a persistence mechanism and a Python self-modification tool (ESET). · AI & Model Security

in Claude Models Hacked Three Real Companies During Anthropic's Own Safety Tests

July 29, 2026

• ESET is tracking 100+ EDR killers, with 60+ still relying on BYOVD against legitimate-but-vulnerable drivers. The team notes the Gentlemen gang runs a shared defense-evasion layer — in-house GentleKiller plus third-party and leaked tools — and can operationalize new BYOVD PoCs within days, a supply they expect to grow as actors weaponize thousands of vulnerable drivers with AI coding assistance (ESET). · Threat Activity

in Artifactory Zero-Days Confirmed as the Hugging Face AI Agent's Escape Route

July 15, 2026

• ESET found 11 old, Microsoft-signed UEFI shim bootloaders that bypass Secure Boot on most UEFI systems. The forgotten Linux-distro shims still carry valid signatures and contain bugs that let an attacker run untrusted code at boot — enabling persistent UEFI bootkits that survive OS reinstalls and evade AV. Reported to CERT/CC. WeLiveSecurity, SC World · Vulnerabilities & Exploits

in Record-Breaking Patch Tuesday Ships With Live Active Directory and SharePoint Zero-Days

June 26, 2026

• ESET detailed Gamaredon's 2025 evolution: six new PowerShell downloaders (PteroDee, PteroDum, PteroPaste, PteroOdd, PteroEffigy, PteroCache) plus the revived PteroSetup weaponizer, 35 spear-phishing campaigns against Ukrainian government/military, and heavy infrastructure laundering via Cloudflare Workers, Microsoft dev tunnels, Loophole, and dead drops on Telegram, Telegraph, Rentry, Dropbox, Supabase and Clever Cloud. WeLiveSecurity, whitepaper + IOCs · Threat Intelligence

in Malware Weaponizes Prompt Injection to Sabotage AI Analysis as Gamaredon Retools Against Ukraine

June 25, 2026

• Operation Endgame dismantled the shared infrastructure behind the Amadey and StealC infostealers, with Microsoft's DCU, Europol, Bitdefender, Bitsight, and ESET taking down 300+ servers and 200+ domains, recovering ~27M stolen credentials, and seizing over $47M; Microsoft also leaned on AI to link the operations in a racketeering suit. Microsoft, The Record, The Register · Threat Intelligence

in Cisco SD-WAN Manager Zero-Day Gives Root via a Malicious CSV as Operation Endgame Smashes Amadey and StealC

June 21, 2026

• ESET published a deep dive on the Gentlemen RaaS's EDR-killer portfolio, centered on the in-house GentleKiller framework (eight variants, each impersonating a different legitimate product) and supplemented with HexKiller, ThrottleBlood, and HavocKiller. Across builds it targets 400+ processes mapped to 48 security products; leaked Gentlemen data confirmed GentleKiller as an internal tool and linked one affiliate to a stealer ESET named OxideHarvest. IoCs are on GitHub (WeLiveSecurity, BleepingComputer). · Ransomware & EDR Evasion
• DeadLock is expanding its abuse of Polygon blockchain smart contracts — moving beyond chat-proxy rotation to host its data-leak site entirely on-chain (75 victims since February), with HTML ransom notes fetching victim data live from the contract (ESET). Nextron flagged KRYBIT, a new double-extortion strain whose YARA profile overlaps heavily with the leaked Babuk codebase (Nextron), and Prinz Eugen emerged prioritizing recently-modified files for faster encryption while leaving no ransom note (BleepingComputer). · Ransomware & EDR Evasion
• ESET uncovered two undocumented Windows variants of the SprySOCKS backdoor (WIN_DRV and WIN_PLUS), attributed with high confidence to China-nexus FishMonger and used against governments in Honduras, Taiwan, Thailand, and Pakistan. WIN_DRV weaponizes a kernel driver to redirect traffic to a hidden TCP port triggered by crafted packet data, with possible UEFI bootkit involvement (WeLiveSecurity, The Hacker News). · Threat Intelligence

in FortiBleed Exposes 86,000 FortiGate Devices as North Korea's Sapphire Sleet Poisons the Mastra npm Catalog

June 20, 2026

• ESET dissected GentleKiller, the in-house EDR-killer at the core of the Gentlemen RaaS portfolio — eight variants, each impersonating a legitimate product, collectively targeting 400+ processes mapped to 48 security products, and combined with externally sourced HexKiller, ThrottleBlood, and HavocKiller. A leak of Gentlemen's own data also linked an affiliate to a stealer ESET named OxideHarvest; IoCs are published. The Hacker News, WeLiveSecurity · Ransomware & Extortion
• DeadLock is expanding its use of Polygon smart contracts — now hosting its leak-site entries on-chain (75 victims since February) in addition to chat-proxy rotation, with notes fetching victim data live from the contracts. ESET · Ransomware & Extortion
• ESET attributed two undocumented Windows variants of the previously Linux-only SprySOCKS backdoor (WIN_DRV, WIN_PLUS) to China-nexus FishMonger; WIN_DRV weaponizes a kernel driver for a passive, hidden-port TCP backdoor triggered by crafted packets, used against governments in Honduras, Taiwan, Thailand, and Pakistan. The Hacker News, WeLiveSecurity · Threat Intelligence & Espionage

in FortiBleed Burns 86,000 FortiGate Devices as Novo Nordisk Loses 1.3TB — Including AI Models — to a Leaked GitHub Token