UPDATE — Toneshell's tenth version abandons custom sockets for WebSocket-over-TLS through WinHTTP, retiring every network signature built on the old channel, and a new hVNC backdoor carries no embedded C2 at all
UPDATE · originally covered Mustang Panda's CoolClient backdoor gains a kernel driver signed with a 2013 certificate that expired in 2014 — and it hides the malware's own C2 traffic by hooking the driver Windows uses to report network state (2026-08-15)
this pipeline covered a CoolClient variant attributed to this actor six days ago, installing a signed kernel driver that filtered its own C2 addresses out of the network data Windows returns to user mode. This is separate research on the same actor from a different lab, and the reason it is worth an update rather than nothing is that one of its two findings retires existing detection content.
Toneshell v10 changes the channel, not just the payload. "Earlier variants relied on custom socket-based communications, while version 10 transitions to secure WebSocket communications using WinHTTP over TLS" (IBM X-Force, 2026-08-20). The implant now speaks through the operating system's own WinHTTP WebSocket routines and additionally queries the user's proxy configuration, so it is proxy-aware. The consequence for a network defender is direct: a signature or filter written against Toneshell's earlier bespoke socket protocol no longer matches anything, and what replaces it is traffic sharing port, protocol and TLS client-stack characteristics with every other WinHTTP-based Windows application and ordinary browser WebSocket session. Detection has to move to the client-stack TLS fingerprint, destination reputation, or endpoint-side visibility of the WebSocket API calls themselves — protocol shape alone no longer discriminates.
X-Force also found three standalone DLL builds of Toneshell v10 reusing the same WebSocket model, command dispatcher and reverse-shell functionality, two of them masquerading under the filename of a PDF-creation component and one as a browser-framework library. Between the dispatcher's command branches sit repeated blocks of wide-character junk strings referencing Harry Potter characters and themes — padding inserted to frustrate analysis.
Havencode: hidden desktop access with nothing to extract from the binary. X-Force had not previously observed this backdoor. Its centre of gravity is hidden Virtual Network Computing, letting an operator connect to an infected machine's desktop and browse it covertly. It ships as a 64-bit DLL alongside a legitimate signed executable and is launched by side-loading, and it takes three modes: a hidden-desktop VNC server on a supplied local port, a view-only mode that attaches to the user's existing desktop to watch without taking input control, and a generic TCP/UDP tunnel the operators used to relay the local VNC server's traffic out to their C2 — though X-Force notes the tunnel may serve any other proxy traffic too.
The detail that matters for hunting is what the file does not hold: "It does not contain any embedded C2 addresses. Instead, the C2 server is provided as command line argument at the time of execution". Static extraction of infrastructure from a recovered sample yields nothing; the address exists only in the process command line at launch, which makes process-creation telemetry with full command-line capture the difference between knowing where it called home and not.
The loader in front of it, which X-Force names Claimloader, copies the side-loading pair into a new installation directory — commonly under the system-wide program-data path — establishes persistence, then recovers embedded shellcode and executes the Toneshell payload by abusing a locale-enumeration API as a callback to transfer execution.
What the deception environment showed that logs would not. X-Force ran two fake victims — an operational technology company specialising in electric grids, and a state-level government agency — and captured the operators live. The evidence of hands-on-keyboard work is mundane and convincing: two commands were mistyped in both incidents, a domain-enumeration command and a wireless-network listing, and on its first attempt the crew launched Havencode with malformed arguments. X-Force's conclusion is that "This evidence is a strong indicator that most of the operator activity was not scripted but performed by hand", corroborated independently by timing — operator-initiated actions fell exclusively within weekday working hours of 08:00 to 18:00 China Standard Time, with activity pausing over a weekend and resuming afterwards. Initial access in the campaign came from a May 2026 email to Indian government recipients carrying a PDF attachment themed as a hydropower cooperation study and imitating Nepal's foreign ministry.
Triage: the side-load pair is the most reliable host-side discriminator, because the legitimate executable is genuinely signed and will pass any signature check — what is anomalous is that binary running from a program-data subdirectory rather than its installed location, with a same-named dependency DLL beside it. For Havencode specifically, look for a process whose command line carries a network address and a local port together with VNC-style mode arguments: the configuration is in the command line by design, so command-line logging is not optional here. On the network side, the honest position is that Toneshell v10's channel is hard to separate from benign WinHTTP WebSocket traffic; the tractable signals are a hidden-desktop VNC session being tunnelled out of a host that has no remote-support tooling deployed, and a rapid sequence of host and network reconnaissance commands — system information, current user, group enumeration, network connections and process listing in quick succession — which X-Force names as the pattern to alert on.
Earlier variants relied on custom socket-based communications, while version 10 transitions to secure WebSocket communications using WinHTTP over TLS.
It does not contain any embedded C2 addresses. Instead, the C2 server is provided as command line argument at the time of execution
This evidence is a strong indicator that most of the operator activity was not scripted but performed by hand.
The observed activity extends a campaign previously reported by Acronis, where ITG27 targeted India's energy sector and government organizations.
ATT&CK mapping
11 techniques mapped from the cited reporting · MITRE ATT&CK v19.2
Initial Access TA0001
T1566.001Phishing: Spearphishing Attachment
Adversaries may send spearphishing emails with a malicious attachment in an attempt to gain access to victim systems. Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email and usually rely upon User Execution to gain execution. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
Execution TA0002
T1574.001Hijack Execution Flow: DLL
Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.
Stealth TA0005
T1027Obfuscated Files or Information
Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit. This is common behavior that can be used across different platforms and the network to evade defenses.
T1036.005Masquerading: Match Legitimate Resource Name or Location
Adversaries may match or approximate the name or location of legitimate files, Registry keys, or other resources when naming/placing them. This is done for the sake of evading defenses and observation.
T1574.001Hijack Execution Flow: DLL
Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.
Discovery TA0007
T1033System Owner/User Discovery
Adversaries may attempt to identify the primary user, currently logged in user, set of users that commonly uses a system, or whether a user is actively using the system. They may do this, for example, by retrieving account usernames or by using OS Credential Dumping. The information may be collected in a number of different ways using other Discovery techniques, because user and username details are prevalent throughout a system and include running process ownership, file/directory ownership, session information, and system logs. Adversaries may use the information from System Owner/User Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions.
T1049System Network Connections Discovery
Adversaries may attempt to get a listing of network connections to or from the compromised system they are currently accessing or from remote systems by querying for information over the network.
T1082System Information Discovery
An adversary may attempt to get detailed information about the operating system and hardware, including version, patches, hotfixes, service packs, and architecture. Adversaries may use this information to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions. This behavior is distinct from Local Storage Discovery which is an adversary's discovery of local drive, disks and/or volumes.
Command and Control TA0011
T1071.001Application Layer Protocol: Web Protocols
Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.
T1090Proxy
Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. Adversaries use these types of proxies to manage command and control communications, reduce the number of simultaneous outbound network connections, provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion. Adversaries may chain together multiple proxies to further disguise the source of malicious traffic.
T1105Ingress Tool Transfer
Adversaries may transfer tools or other files from an external system into a compromised environment. Tools or files may be copied from an external adversary-controlled system to the victim network through the command and control channel or through alternate protocols such as ftp. Once present, adversaries may also transfer/spread tools between victim devices within a compromised environment (i.e. Lateral Tool Transfer).
T1219Remote Access Tools
An adversary may use legitimate remote access tools to establish an interactive command and control channel within a network. Remote access tools create a session between two trusted hosts through a graphical interface, a command line interaction, a protocol tunnel via development or management software, or hardware-level access such as KVM (Keyboard, Video, Mouse) over IP solutions. Desktop support software (usually graphical interface) and remote management software (typically command line interface) allow a user to control a computer remotely as if they are a local user inheriting the user or software permissions. This software is commonly used for troubleshooting, software installation, and system management. Adversaries may similarly abuse response features included in EDR and other defensive tools that enable remote access.
Sources
Update chain
AI-generated · no human review · this permalink is the shareable record for the finding · verify operationally critical claims against the linked primary source.