Proxy: Internal Proxy

Adversaries may use an internal proxy to direct command and control traffic between two or more systems in a compromised environment. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. [1] Adversaries use internal proxies to manage command and control communications inside a compromised environment, to reduce the number of simultaneous outbound network connections, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between infected systems to avoid suspicion. Internal proxy connections may use common peer-to-peer (p2p) networking protocols, such as SMB, to better blend in with the environment.

By using a compromised internal system as a proxy, adversaries may conceal the true destination of C2 traffic while reducing the need for numerous connections to external systems.

ID: T1090.001
Sub-technique of:  T1090
Platforms: ESXi, Linux, Network Devices, Windows, macOS
Version: 1.2
Created: 14 March 2020
Last Modified: 15 April 2025

Procedure Examples

ID Name Description
C0051 APT28 Nearest Neighbor Campaign

During APT28 Nearest Neighbor Campaign, APT28 used the built-in netsh portproxy command to create internal proxies on compromised systems.[2]

G0087 APT39

APT39 used custom tools to create SOCK5 and custom protocol proxies between infected hosts.[3][4]

S0031 BACKSPACE

The "ZJ" variant of BACKSPACE allows "ZJ link" infections with Internet access to relay traffic from "ZJ listen" to a command server.[5]

S0023 CHOPSTICK

CHOPSTICK used a proxy server between victims and the C2 server.[6]

S0154 Cobalt Strike

Cobalt Strike can be configured to have commands relayed over a peer-to-peer network of infected hosts. This can be used to limit the number of egress points, or provide access to a host without direct internet access.[7][8]

S0502 Drovorub

Drovorub can use a port forwarding rule on its agent module to relay network traffic through the client module to a remote host on the same network.[9]

S0038 Duqu

Duqu can be configured to have commands relayed over a peer-to-peer network of infected hosts if some of the hosts do not have Internet access.[10]

S0512 FatDuke

FatDuke can used pipes to connect machines with restricted internet access to remote machines via other infected hosts.[11]

G1016 FIN13

FIN13 has utilized a proxy tool to communicate between compromised assets.[12]

S1198 Gomir

Gomir can start a reverse proxy to initiate connections to arbitrary endpoints in victim networks.[13]

G0126 Higaisa

Higaisa discovered system proxy settings and used them if available.[14]

S0009 Hikit

Hikit supports peer connections.[15]

S0260 InvisiMole

InvisiMole can function as a proxy to create a server that relays communication between the client and C&C server, or between two clients.[16]

S0265 Kazuar

Kazuar has used internal nodes on the compromised network for C2 communications.[17]

G0032 Lazarus Group

Lazarus Group has used a compromised router to serve as a proxy between a victim network's corporate and restricted segments.[18]

G0030 Lotus Blossom

Lotus Blossom has used publicly available tools such as the Venom proxy tool to proxy traffic out of victim environments.[19]

S1060 Mafalda

Mafalda can create a named pipe to listen for and send data to a named pipe-based C2 server.[20]

S1059 metaMain

metaMain can create a named pipe to listen for and send data to a named pipe-based C2 server.[20]

S0051 MiniDuke

MiniDuke can can use a named pipe to forward communications from one compromised machine with internet access to other compromised machines.[11]

S0699 Mythic

Mythic can leverage a peer-to-peer C2 profile between agents.[21]

S1100 Ninja

Ninja can proxy C2 communications including to and from internal agents without internet connectivity.[22][23]

C0014 Operation Wocao

During Operation Wocao, threat actors proxied traffic through multiple infected systems.[24]

S0556 Pay2Key

Pay2Key has designated machines in the compromised network to serve as reverse proxy pivot points to channel communications with C2.[25][26]

S0633 Sliver

Sliver has a built-in SOCKS5 proxying capability allowing for Sliver clients to proxy network traffic through other clients within a victim network.[27]

C0024 SolarWinds Compromise

During the SolarWinds Compromise, APT29 used SSH port forwarding capabilities on public-facing systems, and configured at least one instance of Cobalt Strike to use a network pipe over SMB.[28][29]

G0041 Strider

Strider has used local servers with both local network and Internet access to act as internal proxy nodes to exfiltrate data from other parts of the network without direct Internet access.[30]

S0603 Stuxnet

Stuxnet installs an RPC server for P2P communications.[31]

G0010 Turla

Turla has compromised internal network systems to act as a proxy to forward traffic to C2.[32]

G1047 Velvet Ant

Velvet Ant has tunneled traffic from victims through an internal, compromised host to proxy communications to command and control nodes.[33]

G1017 Volt Typhoon

Volt Typhoon has used the built-in netsh port proxy command to create proxies on compromised systems to facilitate access.[34][35]

S0141 Winnti for Windows

The Winnti for Windows HTTP/S C2 mode can make use of a local proxy.[36]

Mitigations

ID Mitigation Description