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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.1

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.2

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

Item Value
ID T1572
Tactics TA0011
Platforms Linux, Windows, macOS
Version 1.0
Created 15 March 2020
Last Modified 27 March 2020

Procedure Examples

ID Name Description
S1063 Brute Ratel C4 Brute Ratel C4 can use DNS over HTTPS for C2.45
G0114 Chimera Chimera has encapsulated Cobalt Strike‘s C2 protocol in DNS and HTTPS.33
G0080 Cobalt Group Cobalt Group has used the Plink utility to create SSH tunnels.222324
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.78
C0004 CostaRicto During CostaRicto, the threat actors set up remote SSH tunneling into the victim’s environment from a malicious domain.34
S0687 Cyclops Blink Cyclops Blink can use DNS over HTTPS (DoH) to resolve C2 nodes.15
S0038 Duqu Duqu uses a custom command and control protocol that communicates over commonly used ports, and is frequently encapsulated by application layer protocols.18
G0037 FIN6 FIN6 used the Plink command-line utility to create SSH tunnels to C2 servers.21
S0173 FLIPSIDE FLIPSIDE uses RDP to tunnel traffic from a victim environment.19
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.303132
S1044 FunnyDream FunnyDream can connect to HTTP proxies via TCP to create a tunnel to C2.17
S1027 Heyoka Backdoor Heyoka Backdoor can use spoofed DNS requests to create a bidirectional tunnel between a compromised host and its C2 servers.9
S0604 Industroyer Industroyer attempts to perform an HTTP CONNECT via an internal proxy to establish a tunnel.20
S1020 Kevin Kevin can use a custom protocol tunneled through DNS or HTTP.10
G0065 Leviathan Leviathan has used protocol tunneling to further conceal C2 communications and infrastructure.26
G0059 Magic Hound Magic Hound has used Plink to tunnel RDP over SSH.25
S1015 Milan Milan can use a custom protocol tunneled through DNS or HTTP.10
S0699 Mythic Mythic can use SOCKS proxies to tunnel traffic through another protocol.6
S0508 Ngrok Ngrok can tunnel RDP and other services securely over internet connections.11121314
G0049 OilRig OilRig has used the Plink utility and other tools to create tunnels to C2 servers.292827
S0650 QakBot The QakBot proxy module can encapsulate SOCKS5 protocol within its own proxy protocol.16


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.


ID Data Source Data Component
DS0029 Network Traffic Network Connection Creation


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