Fake Software Installers Disable Windows Update and Weaken Microsoft Defender
Fake software-download sites distribute installers that disable Windows Update and weaken Defender, attributed to China-linked cluster Silver Fox.
Microsoft says an active campaign uses counterfeit vendor websites on .com.cn and .hl.cn infrastructure with Chinese-language lures to deliver server-side generated installers that establish scheduled-task persistence, add Defender exclusions, delete shadow copies, and stop services including wuauserv, UsoSvc, uhssvc and WaaSMedicSvc. Victims span healthcare, manufacturing, gaming, technology, logistics, government and education, primarily China-based operations of multinationals and Chinese-speaking users. Microsoft assesses with moderate confidence the activity matches the Silver Fox (Yinhu) cluster, historically tied to Gh0st RAT and ValleyRAT, with C2 over non-standard ports like 5090 and 7088-7090 via domains iualef[.]net and oijfwe[.]net. Kaspersky separately detailed a QN Wallpaper DLL-sideloading chain delivering ValleyRAT.
Dogged Russia-based botnet dismantled after 23-year run
Law enforcement, CrowdStrike and Shadowserver dismantled the 23-year-old Sality P2P botnet that infected more than 11 million devices.
Sality, a Russia-based peer-to-peer botnet active for 23 years and infecting over 11 million devices, was dismantled by law enforcement working with CrowdStrike and the Shadowserver Foundation. CrowdStrike poisoned the botnet's peer list so infected machines permanently disappeared from the operator's view, while domains were seized in a coordinated effort involving the FBI, Justice Department, Europol and authorities from Bulgaria, Hungary and Romania. The financially motivated operation enabled cryptocurrency theft, DDoS attacks and other cyberattacks, and Europol said the effort dates back to 2017; the operators were not named.
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Iranian Hackers Use Telegram-Controlled Malware to Spy on Dissidents and Journalists
FBI, NCSC, and AIVD detail Iran MOIS spyware CHOSEN BRICK/HEAVYGRAM, Telegram-controlled Windows malware spying on dissidents since 2023.
A September 15 joint advisory from the FBI, UK NCSC, and Dutch AIVD attributes the Windows spyware HEAVYGRAM (NCSC name CHOSEN BRICK) to Iran's Ministry of Intelligence and Security, with the campaign dating to autumn 2023 and targeting dissidents, journalists, and activists in the UK, US, Netherlands, and worldwide. Delivered via messages impersonating known contacts or tech support, the malware assigns each victim a dedicated Telegram bot for command-and-control and exfiltration, and can take screenshots, record microphone audio, steal Telegram/WhatsApp data, saved passwords, and emails, download more malware, and wipe the computer. Persistence uses a registry Run key (SMQDService or winappx) plus Microsoft Defender exclusions, with stolen data exiting via Telegram and cloud storage services like Vultr and Storj. The US Justice Department seized four pro-Iranian leak sites in March that had published stolen victim data.
Hackers deploy Linux rootkit on F5 BIG-IP APM devices, hiding web shell in memory
Sophos analyzed a Linux rootkit, tracked as PoisonedRefresh, on hacked F5 BIG-IP APM devices hiding an in-memory web shell linked to exploited CVE-2025-53521.
Sophos and ESET analyzed an implant (named PoisonedRefresh by ESET) deployed on compromised F5 BIG-IP APM appliances, which serves enterprise, financial, government, and public sector deployments. The second-stage payload intercepts __libc_start_main, hooks Apache's APR module loader (apr_dso_load), RC4-encodes key strings, and rewrites PHP file reads in memory to embed a web shell inside legitimate scripts like apm_css.php3, full_wt.php3, and webtop_popup_css.php3, leaving on-disk files unchanged. A related installer component infects /usr/sbin/httpd, persists across BIG-IP upgrade images, modifies SELinux configuration, and deploys the payload. The malware also creates a Unix domain socket at /run/bigtlog.pipe that hands authenticated local connections to /bin/bash; F5 links the activity to CVE-2025-53521, an unauthenticated RCE in BIG-IP APM already exploited in the wild.
Hackers Disguise CHOSEN BRICK Malware as AI Apps, Antivirus Software and MRI Results
NCSC, FBI, and AIVD warn Iranian state-linked actors deliver CHOSEN BRICK Windows spyware via fake AI apps, antivirus installers, and MRI-result lures.
A joint advisory from the UK NCSC, FBI, and Dutch AIVD details CHOSEN BRICK (FBI tracking name: HEAVYGRAM), Iranian state-linked Windows spyware targeting dissidents, activists, and journalists worldwide since at least 2025. Lures impersonate Pictory, RunwayML, Norton Antivirus, Telegram, Adobe Flash Player, and KeePass, and operators pivot conversations from corporate to personal devices to bypass enterprise controls. The spyware persists via Registry Run keys, adds Microsoft Defender exclusions, uses per-victim Telegram bots for command-and-control, and exfiltrates screenshots, audio, email, and chat data via Telegram and cloud services, with some victim data appearing on pro-Iranian leak sites.
KREMLIN Banking Malware Hijacks Chrome and Edge to Steal Credentials and Session Tokens
Elastic Security Labs details KREMLIN, Brazilian banking malware using malicious Chrome/Edge extensions and Ethereum smart contracts to steal credentials and session tokens.
Elastic Security Labs documents KREMLIN (tracked as REF9334), a Brazilian banking malware toolkit active since at least May 2025 that impersonates a dozen Brazilian banks. It uses multi-stage JavaScript loaders, a C++ installer that DLL-sideloads via a legitimate SentinelOne binary, and a malicious Chrome/Edge extension named 'AVSync System Inc.' Ethereum smart contracts act as dead-drop resolvers for C2 endpoints, a shift that occurred May 19, 2026, making infrastructure hard to disrupt. The extension harvests cookies, sessionStorage/localStorage, browsing history, screenshots, and full page HTML via WebSocket plus CSS-disguised polling endpoints. The group has run seven distinct campaigns and also distributes Pulsar RAT and Remcos RAT.