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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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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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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.
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APT group HoneyMyte upgrades CoolClient: the backdoor gets a kernel-level Windows rootkit
Kaspersky reports APT group HoneyMyte upgraded its CoolClient backdoor with a kernel-mode Windows rootkit hiding processes, files, and network connections.
Kaspersky researchers discovered a new variant of the HoneyMyte CoolClient backdoor equipped with a kernel-mode Windows rootkit driver. The rootkit hides malicious processes, files, and network connections from security tools and threat analysts, significantly increasing the backdoor's stealth. The report documents an upgrade to the APT group's backdoor tooling with a kernel-level implant.
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Microsoft Releases Patches for 132 Vulnerabilities, Including 6 Under Active Attack
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