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Proxy Port Activity to the Internet

This rule detects events that may describe network events of proxy use to the Internet. It includes popular HTTP proxy ports and SOCKS proxy ports. Typically, environments will use an internal IP address for a proxy…

Description

This rule detects events that may describe network events of proxy use to the Internet. It includes popular HTTP proxy ports and SOCKS proxy ports. Typically, environments will use an internal IP address for a proxy server. It can also be used to circumvent network controls and detection mechanisms.

Detection logic

Its licence does not clear it for publishing here

Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.

Detection requirements

Log source category
event_index

Known benign triggers

  • Some proxied applications may use these ports but this usually occurs in local traffic using private IPs which this rule does not match. Proxies are widely used as a security technology but in enterprise environments this is usually local traffic which this rule does not match. If desired, internet proxy services using these ports can be added to allowlists. Some screen recording applications may use these ports. Proxy port activity involving an unusual source or destination may be more suspicious. Some cloud environments may use this port when VPNs or direct connects are not in use and cloud instances are accessed across the Internet. Because these ports are in the ephemeral range, this rule may false under certain conditions such as when a NATed web server replies to a client which has used a port in the range by coincidence. In this case, such servers can be excluded if desired.

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