LoFP LoFP / 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.

Techniques

Sample rules

Proxy Port Activity to the Internet

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

event.category:(network or network_traffic) and network.transport:tcp and (destination.port:(1080 or 3128 or 8080) or event.dataset:zeek.socks) and
  source.ip:(
    10.0.0.0/8 or
    172.16.0.0/12 or
    192.168.0.0/16
  ) and
  not destination.ip:(
    10.0.0.0/8 or
    127.0.0.0/8 or
    169.254.0.0/16 or
    172.16.0.0/12 or
    192.168.0.0/16 or
    224.0.0.0/4 or
    "::1" or
    "FE80::/10" or
    "FF00::/8"
  )