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ATT&CK Technique

Internal Proxy

T1090.001 · command-and-control

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. 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.

ESXiLinuxmacOSNetwork DevicesWindows

Actors Using This

14
iranAgrius
latin_america_brazilian_organized_cybercrimeAmavaldo
unknown_likely_russia_alignedAnubis Ransomware
chinaAPT10
chinaAPT1
russiaAPT28
russiaAPT29
chinaAPT31
iranAPT33
iranOilRig
chinaAPT40
china_state_sponsored_mandiant_canonical_microsoft_mulberry_typhoonAPT5 (UNC2630 / UNC2717 / Mulberry Typhoon)

Likely Attack Path

Techniques the same actors pair with this one distinctively - those showing up among actors who use this technique noticeably more than across all actors (lift > 1.15), grouped by kill-chain phase. The × is that lift multiplier; the shared-actor count is in the tooltip. A near-universal technique pairs with everything at baseline, so its list is short by design.
initial-access earlier
privilege-escalation earlier

Atomic Tests

3
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
shlinux, macosConnection Proxy
Enable traffic redirection. Note that this test may conflict with pre-existing system configuration.
export #{proxy_scheme}_proxy=#{proxy_server}:#{proxy_port}
curl #{test_url}
shmacosConnection Proxy for macOS UI
Enable traffic redirection on macOS UI (not terminal). The test will modify and enable the "Web Proxy" and "Secure Web Proxy" settings in System Preferences => Network => Advanced => Proxies for the specified network interface. Note that this test may conflict with pre-existing system configuration.
networksetup -setwebproxy #{interface} #{proxy_server} #{proxy_port}
networksetup -setsecurewebproxy #{interface} #{proxy_server} #{proxy_port}
powershellelevatedwindowsportproxy reg key
Adds a registry key to set up a proxy on the endpoint at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PortProxy\v4tov4 Upon execution there will be a new proxy entry in netsh netsh interface portproxy show all
netsh interface portproxy add v4tov4 listenport=#{listenport} connectport=#{connectport} connectaddress=#{connectaddress}

Mitigations

1
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1031Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

Detection Coverage

1/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 6
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none

Comply & Defend

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