T1090.002: External Proxy

Data from MITRE ATT&CK®:

Adversaries may use an external proxy to 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. (Citation: Trend Micro APT Attack Tools) Adversaries use these types of proxies to manage command and control communications, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths to avoid suspicion.

External connection proxies are used to mask the destination of C2 traffic and are typically implemented with port redirectors. Compromised systems outside of the victim environment may be used for these purposes, as well as purchased infrastructure such as cloud-based resources or virtual private servers. Proxies may be chosen based on the low likelihood that a connection to them from a compromised system would be investigated. Victim systems would communicate directly with the external proxy on the Internet and then the proxy would forward communications to the C2 server.

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Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

Network Traffic Content (Network Traffic)

Logged network traffic data showing both protocol header and body values (ex: PCAP)

Network Connection Creation (Network Traffic)

Initial construction of a network connection, such as capturing socket information with a source/destination IP and port(s) (ex: Windows EID 5156, Sysmon EID 3, or Zeek conn.log)

Network Traffic Flow (Network Traffic)

Summarized network packet data, with metrics, such as protocol headers and volume (ex: Netflow or Zeek http.log)

RDP over Reverse SSH Tunnel WFP

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