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T1572 Protocol Tunneling

Adversaries may tunnel network communications to and from a victim system within a separate protocol to avoid detection/network filtering and/or enable access to otherwise unreachable systems. Tunneling involves explicitly encapsulating a protocol within another. This behavior may conceal malicious traffic by blending in with existing traffic and/or provide an outer layer of encryption (similar to a VPN). Tunneling could also enable routing of network packets that would otherwise not reach their intended destination, such as SMB, RDP, or other traffic that would be filtered by network appliances or not routed over the Internet.

There are various means to encapsulate a protocol within another protocol. For example, adversaries may perform SSH tunneling (also known as SSH port forwarding), which involves forwarding arbitrary data over an encrypted SSH tunnel.41

Protocol Tunneling may also be abused by adversaries during Dynamic Resolution. Known as DNS over HTTPS (DoH), queries to resolve C2 infrastructure may be encapsulated within encrypted HTTPS packets.3

Adversaries may also leverage Protocol Tunneling in conjunction with Proxy and/or Protocol or Service Impersonation to further conceal C2 communications and infrastructure.

Item Value
ID T1572
Sub-techniques
Tactics TA0011
Platforms ESXi, Linux, Windows, macOS
Version 1.1
Created 15 March 2020
Last Modified 24 October 2025

Procedure Examples

ID Name Description
C0034 2022 Ukraine Electric Power Attack During the 2022 Ukraine Electric Power Attack, Sandworm Team deployed the GOGETTER tunneler software to establish a “Yamux” TLS-based C2 channel with an external server(s).53
S1063 Brute Ratel C4 Brute Ratel C4 can use DNS over HTTPS for C2.67
C0027 C0027 During C0027, Scattered Spider used SSH tunneling in targeted environments.51
C0032 C0032 During the C0032 campaign, TEMP.Veles used encrypted SSH-based PLINK tunnels to transfer tools and enable RDP connections throughout the environment.52
G0114 Chimera Chimera has encapsulated Cobalt Strike’s C2 protocol in DNS and HTTPS.35
G1021 Cinnamon Tempest Cinnamon Tempest has used the Iox and NPS proxy and tunneling tools in combination create multiple connections through a single tunnel.46
G0080 Cobalt Group Cobalt Group has used the Plink utility to create SSH tunnels.434445
S0154 Cobalt Strike Cobalt Strike uses a custom command and control protocol that is encapsulated in HTTP, HTTPS, or DNS. In addition, it conducts peer-to-peer communication over Windows named pipes encapsulated in the SMB protocol. All protocols use their standard assigned ports.2425
C0004 CostaRicto During CostaRicto, the threat actors set up remote SSH tunneling into the victim’s environment from a malicious domain.56
C0029 Cutting Edge During Cutting Edge, threat actors used Iodine to tunnel IPv4 traffic over DNS.55
S0687 Cyclops Blink Cyclops Blink can use DNS over HTTPS (DoH) to resolve C2 nodes.28
S0038 Duqu Duqu uses a custom command and control protocol that communicates over commonly used ports, and is frequently encapsulated by application layer protocols.19
G1003 Ember Bear Ember Bear has used ProxyChains to tunnel protocols to internal networks.34
G1016 FIN13 FIN13 has utilized web shells and Java tools for tunneling capabilities to and from compromised assets.29
G0037 FIN6 FIN6 used the Plink command-line utility to create SSH tunnels to C2 servers.31
G0046 FIN7 FIN7 has tunneled C2 traffic via OpenSSH.33
S0173 FLIPSIDE FLIPSIDE uses RDP to tunnel traffic from a victim environment.26
G0117 Fox Kitten Fox Kitten has used protocol tunneling for communication and RDP activity on compromised hosts through the use of open source tools such as ngrok and custom tool SSHMinion.404142
S1144 FRP FRP can tunnel SSH and Unix Domain Socket communications over TCP between external nodes and exposed resources behind firewalls or NAT.5
S1044 FunnyDream FunnyDream can connect to HTTP proxies via TCP to create a tunnel to C2.20
S1027 Heyoka Backdoor Heyoka Backdoor can use spoofed DNS requests to create a bidirectional tunnel between a compromised host and its C2 servers.14
S0604 Industroyer Industroyer attempts to perform an HTTP CONNECT via an internal proxy to establish a tunnel.22
S1020 Kevin Kevin can use a custom protocol tunneled through DNS or HTTP.21
G0065 Leviathan Leviathan has used protocol tunneling to further conceal C2 communications and infrastructure.50
S1141 LunarWeb LunarWeb can run a custom binary protocol under HTTPS for C2.18
G0059 Magic Hound Magic Hound has used Plink to tunnel RDP over SSH.30
S1015 Milan Milan can use a custom protocol tunneled through DNS or HTTP.21
G0129 Mustang Panda Mustang Panda has leveraged OpenSSH (sshd.exe) to execute commands, transfer files and spread across the environment communicating over SMB port 445.47
S0699 Mythic Mythic can use SOCKS proxies to tunnel traffic through another protocol.12
S1189 Neo-reGeorg Neo-reGeorg can tunnel data in and out of targeted networks.13
S0508 ngrok ngrok can tunnel RDP and other services securely over internet connections.109118
G0049 OilRig OilRig has used the Plink utility and other tools to create tunnels to C2 servers.39373638
S0650 QakBot The QakBot proxy module can encapsulate SOCKS5 protocol within its own proxy protocol.27
S1187 reGeorg reGeorg can tunnel TCP sessions including RDP, SSH, and SMB through HTTP.151617
G1045 Salt Typhoon Salt Typhoon has modified device configurations to create and use Generic Routing Encapsulation (GRE) tunnels.32
G1015 Scattered Spider Scattered Spider has installed protocol-tunneling tools on VMware vCenter and adversary-controlled VMs, including Teleport.sh, Chisel (configured to communicate with trycloudflare[.]com subdomains), MobaXterm, ngrok, Pinggy, and Teleport.4849
C0058 SharePoint ToolShell Exploitation During SharePoint ToolShell Exploitation, threat actors utilized ngrok tunnels to deliver PowerShell payloads.54
S0022 Uroburos Uroburos has the ability to communicate over custom communications methodologies that ride over common network protocols including raw TCP and UDP sockets, HTTP, SMTP, and DNS.23

Mitigations

ID Mitigation Description
M1037 Filter Network Traffic Consider filtering network traffic to untrusted or known bad domains and resources.
M1031 Network Intrusion Prevention Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.

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