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.
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| I&S-03 | Network Security | mitigates | T1090.002 | External Proxy |
Comments
This control provides for monitoring, encrypting, and restricting communications between environments. Network intrusion detection and prevention systems that use network signatures to identify traffic for specific malware or unexpected protocol standards and traffic flows can be used to mitigate activity at the network level. Virtual private cloud (VPC) security groups and network access control lists (NACLs) can be used to limit traffic between systems and mitigate use of a connection proxy for communications.
References
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| I&S-06 | Segmentation and Segregation | mitigates | T1090.002 | External Proxy |
Comments
This control provides for appropriately segmented and segregated cloud environments. Virtual private cloud (VPC) security groups and network access control lists (NACLs) can be used to limit traffic between systems and mitigate use of a connection proxy for communications.
References
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| I&S-09 | Network Defense | mitigates | T1090.002 | External Proxy |
Comments
This control provides for the implementation of defense-in-depth network security controls for securing the cloud environment. Network intrusion detection and prevention systems that use network signatures to identify traffic for specific malware or unexpected protocol standards and traffic flows can be used to mitigate activity at the network level. Virtual private cloud (VPC) security groups and network access control lists (NACLs) can be used to limit traffic between systems and mitigate use of a connection proxy for communications.
References
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