SECEF reverse web gateway (pull mode)

This repository contains a small daemon that fetches security alerts encoded using IDMEFv1 XML messages from a remote web server and forwards them to a web gateway.

This daemon is useful in contexts where the IDMEF sensors are unable to send their alerts to a manager directly (e.g. in a DMZ) and instead expect the manager to establish a reverse connection to fetch new alerts periodically.

An implementation of a compatible web gateway is also available at https://github.com/SECEF/secef-web-gateway. This particular implementation forwards IDMEFv1 messages to a Prelude SIEM manager.

For more information about the Intrusion Detection Message Exchange Format (IDMEF) version 1, see https://tools.ietf.org/html/rfc4765.

For more information about Prelude SIEM, see https://www.prelude-siem.org/.

Installation

This module has been tested with CentOS 7.x.

Disable SELinux:

sudo setenforce 0

Note

You may want to disable SELinux permanently by editing /etc/selinux/config and rebooting.

Install dependencies:

sudo yum install -y epel-release
sudo yum install -y python-lxml python-requests

On both the sensor and the manager, create /usr/local/secef/ and copy all the files into that folder.

Install the script on the sensor:

sudo ln -s /usr/local/secef/reverse-server.service       /etc/systemd/system/
sudo ln -s /usr/local/secef/secef.xml                    /etc/firewalld/services/
sudo systemctl daemon-reload
sudo systemctl enable reverse-server.service
sudo systemctl reload firewalld
sudo firewall-cmd --add-service=secef --permanent
sudo firewall-cmd --add-service=secef

Install the script on the manager:

sudo ln -s /usr/local/secef/[email protected]  /etc/systemd/system/
sudo ln -s /usr/local/secef/[email protected]    /etc/systemd/system/
sudo ln -s /usr/local/secef/http-proxy           /etc/sysconfig/
sudo systemctl daemon-reload
sudo systemctl enable http-proxy@<profile>.timer

(replace <profile> in the commands above with an alphanumeric identifier)

Usage

On the sensor

Start the local server:

/usr/local/bin/reverse-server.py --cert server.crt --key server.key --cacert CA.crt

The --cert, --key and --cacert options are mandatory. You may also want to run /usr/local/bin/reverse-server.py --help to get more information on other available options.

On the manager

To query the server manually (assuming the default port is used), run:

curl -s -S --cert client.crt --key client.key --cacert CA.crt https://$(hostname):3128/

The http-proxy service will periodically fetch IDMEF messages from a remote sensor and then forward those messages to Prelude SIEM's IDMEF web gateway.

Several sensors can be queried by enabling multiple instances of the service's timer, e.g.:

sudo systemctl enable [email protected] [email protected]

The file /etc/sysconfig/http-proxy serves as a common configuration file for every instance, while /etc/sysconfig/http-proxy@{profile} serves as an instance-specific configuration file for the instance named profile.

Note

The same TLS settings (e.g. X.509 certificate) will be used both when fetching messages from the sensor and when forwarding them to Prelude SIEM's IDMEF web gateway.