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Hackers breach F5 BIG-IP APM devices to deploy Linux rootkit
Sophos analyzed a Linux rootkit on F5 BIG-IP APM devices that injects a fileless PHP web shell, likely after CVE-2025-53521 exploitation.
Sophos analyzed a Linux rootkit targeting F5 BIG-IP APM environments, also tracked by ESET as PoisonedRefresh, which hijacks Apache's apr_dso_load module loader to inject a fileless PHP web shell into memory. The implant intercepts __libc_start_main, hides strings with RC4, creates a password-protected local UNIX socket backdoor for interactive Bash access, and persists across BIG-IP upgrade images while modifying SELinux configuration. It is likely a second-stage payload following exploitation of CVE-2025-53521, a critical RCE flaw F5 reclassified from a DoS issue in March. The ShadowServer Foundation tracked 795 F5 BIG-IP APM endpoints exposed online.
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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.
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Red Heron Hackers Exploit Critical Gitea RCE to Steal Source Code and Deploy Linux Rootkit
PRC-linked Red Heron exploits critical Gitea RCE CVE-2026-60004 to steal source code and deploy JITTERLY implant with SIXZUT LD_PRELOAD rootkit; victims span five countries.
Acronis Threat Research Unit attributes a campaign to Chinese-speaking threat actor Red Heron, which weaponized CVE-2026-60004, a CVSS 9.8 RCE in Gitea versions 1.17 through 1.27.0, patched in 1.27.1 on July 27, 2026. The actor built an automated exploitation framework after a public PoC appeared, scanned 1,386 internet-exposed Gitea instances across seven countries, and separately listed 477 Taiwan-based systems across defense, energy, elections, and AI sectors. Confirmed victims include organizations in Canada, Argentina, Taiwan, the US, and Sri Lanka, with a Canadian renewable-energy firm hit in 22 sessions and a Taiwanese industrial automation firm losing hundreds of repositories including SCADA/HMI tools. Red Heron deploys the JITTERLY Linux implant (30+ commands, AES-128-GCM, Adaptix-like protocol) and the SIXZUT LD_PRELOAD rootkit disguised as libglthread.so.2, and moved laterally into a Synology/Proxmox environment to steal VM backups.
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UAT-10147 Uses AI to Scale Server Attacks, Deploys SPECTRE With EDR Bypass and Linux Rootkit
Cisco Talos exposes UAT-10147, a Chinese-speaking group using AI tools to automate intrusions, deploy SPECTRE, BadIIS, and rootkits against web servers worldwide.
Cisco Talos detailed UAT-10147, a Chinese-speaking cybercrime group conducting SEO fraud and data theft against Windows and Linux web servers in education, media, technology, and gaming sectors, with most victims in Brazil, Bolivia, China, Canada, and Vietnam. The actor exploits publicly disclosed vulnerabilities for initial access, including Zimbra (CVE-2022-27925) and Alibaba Nacos (CVE-2021-29441), and abuses Linux LPE flaws like CVE-2022-0847 and CVE-2021-3156 for root. Its toolset includes AI-assisted frameworks DeepAudit and PentestGPT, plus implants such as SPECTRE, BadIIS, Quasar RAT, Gh0stCringe, and Noodle RAT. An exposed directory contained a target list of roughly 170,000 URLs, with the US, India, UK, Germany, and Netherlands as top destinations.
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Mustang Panda Upgrades CoolClient With a Kernel Rootkit
Mustang Panda's updated CoolClient backdoor deploys a signed kernel driver to hide processes, files and network activity in Asian intrusions.
Kaspersky analysis shows Mustang Panda (HoneyMyte) upgraded its CoolClient espionage backdoor with a signed kernel-mode driver installed as a Windows service, communicating via IOCTL requests to hide processes, files and registry entries. In a Myanmar campaign the actor deployed PlugX first, then CoolClient via a fake Windows Defender directory and Sangfor defender.exe DLL sideloading, with scheduled task and AutoRun persistence and UAC bypass. The updated variant was observed in intrusions across Pakistan, Mongolia and Myanmar, with victims also in Russia including confirmed government entities.
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