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.
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.
Adversaries may also leverage Protocol Tunneling in conjunction with Proxy and/or Protocol or Service Impersonation to further conceal C2 communications and infrastructure.
How it's found
Detection Strategy for Protocol Tunneling accross OS platforms.: Processes such as plink.exe, ssh.exe, or netsh.exe establishing outbound network connections where traffic patterns show encapsulated protocols (e.g., RDP over SSH). Defender observations include anomalous process-to-network relationships, large asymmetric data flows, and port usage mismatches. sshd, socat, or custom binaries initiating port forwarding or encapsulating traffic (e.g., RDP, SMB) through SSH or HTTP. Defender sees abnormal connect/bind syscalls, encrypted traffic on ports typically used for non-encrypted services, and outlier traffic volume patterns. launchd or user-invoked processes (ssh, socat) encapsulating traffic via SSH tunnels, VPN-style tooling, or DNS-over-HTTPS clients. Defender sees outbound TLS traffic with embedded DNS or RDP payloads. VMware daemons or user processes encapsulating traffic (e.g., guest VMs tunneling via hostd). Defender sees network services inside ESXi creating flows inconsistent with management plane traffic, such as SSH forwarding or DNS-over-HTTPS from management interfaces.
Standards mapping
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is 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. 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. Adversaries may also leverage Protocol Tunneling in conjunction with Proxy and/or Protocol or Service Impersonation to further conceal C2 communications and infrastructure.
Which tactics does T1572 belong to?
T1572 maps to the Command and Control tactic.
Does TurboPentest test for Protocol Tunneling?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related MITRE ATT&CK techniques
About this reference
These security references are maintained by IntegSec, an offensive-security firm whose team holds CISSP, OSCP, and OSCE certifications and has run thousands of penetration tests. Content is kept current as tools, standards, and attack techniques evolve.
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