Hackers Use Popular Messaging Services to Control New Windows Backdoors

A financially motivated threat group known as Toy Ghouls has begun using two custom Windows backdoors that communicate through popular messaging and broker services.

The tools give attackers a discreet way to run commands, collect system details, and maintain control over compromised devices.

The campaign marks a change for the group, which had previously relied heavily on public tools and leaked ransomware builders.

Its move to custom malware suggests a broader effort to stay inside victim networks longer while making activity harder for security teams to spot.

Analysts at Securelist identified the malware in early July 2026 and linked it to Toy Ghouls, also tracked as Bearlyfy, Laboo.boo, and Feral Wolf. The group has targeted Russian organizations since 2025 and has previously been associated with its own GenieLocker ransomware.

The new backdoors are called mqtt-bird-agent 0.1.0 and matrix-bird-agent 0.1.0. They are delivered after attackers gain access to an organization, showing how a small initial breach can develop into a persistent and serious compromise.

Kaspersky said in a report shared with Cyber Security News (CSN) that the tools provide full control over an infected Windows device.

Hackers Use Popular Messaging Services

Toy Ghouls uses Windows Remote Management, or WinRM, to place the backdoors and their configuration files on already compromised systems.

The attackers use Evil-WinRM and WinRM-fs, tools that can help move files and run remote commands across Windows environments.

WinRM is widely used for legitimate administration, which can make malicious use difficult to identify without close monitoring.

Organizations have faced similar risks from Windows Remote Management abuse, where attackers use valid access and remote sessions to move deeper into a network. The HiveMQ version uses the public broker.hivemq.com MQTT service as its command-and-control channel.

It reports whether a device is online, sends information such as processor usage and free memory, and retrieves instructions that are then run through a hidden PowerShell process.

Using a broker service allows attackers to blend malicious traffic with normal internet activity. The approach resembles an earlier MQTT command channel used by WailingCrab, demonstrating why familiar cloud and messaging infrastructure can complicate network investigations.

The second version uses an attacker-controlled Element server based on the Matrix protocol. It sends device status messages to a designated room, receives commands from an account called panel-bot, and executes those instructions through the Windows command line.

Both variants can run interactively or install themselves as Windows services, allowing them to start again after a reboot. This persistence method makes the infection more dangerous because an attacker may regain access even after the original remote session has ended.

Persistence and Defensive Response

The malware stores its settings in a config.toml file before protecting sensitive fields with encryption tied to the infected computer.

On the Element variant, the file is deleted after first use and the information is moved into the Windows registry, reducing the number of obvious artifacts left on disk.

Security teams should review WinRM access, limit it to approved management systems, and investigate unusual remote PowerShell activity.

They should also watch for unexpected services named cplsupport or wtas, suspicious configuration files in ProgramData folders, and outbound traffic involving the listed messaging infrastructure.

Administrators should treat remote-management credentials as high-value assets and enforce strong authentication for privileged accounts.

Recent incidents involving the Teams and Quick Assist campaign show how social engineering and trusted Windows tools can be combined to create a path toward wider network access.

The discovery also reinforces the value of checking for quiet backdoor behavior, rather than looking only for known ransomware activity.

A recent Windows backdoor investigation similarly highlighted how attackers can minimize visible network signals while waiting for instructions.

Toy Ghouls’ use of MQTT and Element does not mean the services themselves are malicious. Instead, the case shows how threat actors can misuse legitimate or common technology to hide command traffic, gather system data, and keep control of compromised Windows systems for longer periods.

Indicators of compromise (IoCs):-

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