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T1090 Proxy

Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. 1 Adversaries use these types of proxies to manage command and control communications, reduce the number of simultaneous outbound network connections, provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion. Adversaries may chain together multiple proxies to further disguise the source of malicious traffic.

Adversaries can also take advantage of routing schemes in Content Delivery Networks (CDNs) to proxy command and control traffic.

Item Value
ID T1090
Sub-techniques T1090.001, T1090.002, T1090.003, T1090.004
Tactics TA0011
Platforms Linux, Network, Windows, macOS
Version 3.1
Created 31 May 2017
Last Modified 30 August 2021

Procedure Examples

ID Name Description
G0096 APT41 APT41 used a tool called CLASSFON to covertly proxy network communications.23
S0456 Aria-body Aria-body has the ability to use a reverse SOCKS proxy module.19
S0347 AuditCred AuditCred can utilize proxy for communications.21
S0245 BADCALL BADCALL functions as a proxy server between the victim and C2 server.42
S0268 Bisonal Bisonal has supported use of a proxy server.16
G0108 Blue Mockingbird Blue Mockingbird has used frp, ssf, and Venom to establish SOCKS proxy connections.49
C0017 C0017 During C0017, APT41 used the Cloudflare CDN to proxy C2 traffic.10
S0348 Cardinal RAT Cardinal RAT can act as a reverse proxy.18
G0052 CopyKittens CopyKittens has used the AirVPN service for operational activity.47
S0384 Dridex Dridex contains a backconnect module for tunneling network traffic through a victim’s computer. Infected computers become part of a P2P botnet that can relay C2 traffic to other infected peers.2425
G1006 Earth Lusca Earth Lusca adopted Cloudflare as a proxy for compromised servers.48
G0117 Fox Kitten Fox Kitten has used the open source reverse proxy tools including FRPC and Go Proxy to establish connections from C2 to local servers.505152
S1044 FunnyDream FunnyDream can identify and use configured proxies in a compromised network for C2 communication.12
S0690 Green Lambert Green Lambert can use proxies for C2 traffic.4041
S0246 HARDRAIN HARDRAIN uses the command cmd.exe /c netsh firewall add portopening TCP 443 “adp” and makes the victim machine function as a proxy server.32
S0376 HOPLIGHT HOPLIGHT has multiple proxy options that mask traffic between the malware and the remote operators.26
S0040 HTRAN HTRAN can proxy TCP socket connections to obfuscate command and control infrastructure.34
S0283 jRAT jRAT can serve as a SOCKS proxy server.15
S0487 Kessel Kessel can use a proxy during exfiltration if set in the configuration.11
S1051 KEYPLUG KEYPLUG has used Cloudflare CDN associated infrastructure to redirect C2 communications to malicious domains.10
S0669 KOCTOPUS KOCTOPUS has deployed a modified version of Invoke-Ngrok to expose open local ports to the Internet.37
G1004 LAPSUS$ LAPSUS$ has leverage NordVPN for its egress points when targeting intended victims.44
G0059 Magic Hound Magic Hound has used Fast Reverse Proxy (FRP) for RDP traffic.53
S0108 netsh netsh can be used to set up a proxy tunnel to allow remote host access to an infected host.9
S0198 NETWIRE NETWIRE can implement use of proxies to pivot traffic.20
S0508 Ngrok Ngrok can be used to proxy connections to machines located behind NAT or firewalls.3334
C0013 Operation Sharpshooter For Operation Sharpshooter, the threat actors used the ExpressVPN service to hide their location.55
C0014 Operation Wocao During Operation Wocao, threat actors used a custom proxy tool called “Agent” which has support for multiple hops.54
S0435 PLEAD PLEAD has the ability to proxy network communications.27
G1005 POLONIUM POLONIUM has used the AirVPN service for operational activity.47
S0378 PoshC2 PoshC2 contains modules that allow for use of proxies in command and control.6
S0262 QuasarRAT QuasarRAT can communicate over a reverse proxy using SOCKS5.78
S0629 RainyDay RainyDay can use proxy tools including boost_proxy_client for reverse proxy functionality.38
S0332 Remcos Remcos uses the infected hosts as SOCKS5 proxies to allow for tunneling and proxying.5
G0034 Sandworm Team Sandworm Team‘s BCS-server tool can create an internal proxy server to redirect traffic from the adversary-controlled C2 to internal servers which may not be connected to the internet, but are interconnected locally.45
S0461 SDBbot SDBbot has the ability to use port forwarding to establish a proxy between a target host and C2.13
S0273 Socksbot Socksbot can start SOCKS proxy threads.14
S0615 SombRAT SombRAT has the ability to use an embedded SOCKS proxy in C2 communications.36
S0436 TSCookie TSCookie has the ability to proxy communications with command and control (C2) servers.31
G0010 Turla Turla RPC backdoors have included local UPnP RPC proxies.43
S0263 TYPEFRAME A TYPEFRAME variant can force the compromised system to function as a proxy server.17
S0386 Ursnif Ursnif has used a peer-to-peer (P2P) network for C2.2930
S0207 Vasport Vasport is capable of tunneling though a proxy.39
S0670 WarzoneRAT WarzoneRAT has the capability to act as a reverse proxy.28
G0124 Windigo Windigo has delivered a generic Windows proxy Win32/Glubteta.M. Windigo has also used multiple reverse proxy chains as part of their C2 infrastructure.46
S0117 XTunnel XTunnel relays traffic between a C2 server and a victim.35
S0412 ZxShell ZxShell can set up an HTTP or SOCKS proxy.2322

Mitigations

ID Mitigation Description
M1037 Filter Network Traffic Traffic to known anonymity networks and C2 infrastructure can be blocked through the use of network allow and block lists. It should be noted that this kind of blocking may be circumvented by other techniques like Domain Fronting.
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. Signatures are often for unique indicators within protocols and may be based on the specific C2 protocol used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools. 2
M1020 SSL/TLS Inspection If it is possible to inspect HTTPS traffic, the captures can be analyzed for connections that appear to be domain fronting.

Detection

ID Data Source Data Component
DS0029 Network Traffic Network Connection Creation

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