Detecting SSH bruteforce attacks using triggers in QoE

Triggers are used to search data in QoE Stor by specified parameters. When a trigger fires, one of the following actions can occur:

notification in GUI

HTTP action

email delivery

Required SSG DPI options:

Statistics gathering and analysis on protocols and directions

Subscriber notifications

Required additional modules:

DPIUI2 (GUI - Graphical User Interface)

Implementation and administration

System trigger for detecting SSH bruteforce attacks

The trigger for detecting SSH bruteforce attacks (name — "ssh bruteforce") is a system trigger and is available in "QoE analytics" → "Triggers and notifications" (disabled by default).

General trigger information

Trigger name: "ssh bruteforce";

Days of week — all;

Check frequency — 10 minutes;

Trigger activation frequency — 0;

Start/end dates and times can be set if needed.

Every day, a check will be performed every 10 minutes according to the conditions described below.

Queries

For this trigger a non-editable query is preset with the following parameters:

Table to scan: Raw full netflow → Tables → Attacks detection → Ssh bruteforce;

Period from: now - 30 minutes

Period to: now - 20 minutes

Conditions

Add two "+" fields

Link – AND

Function – avg

Series in field 1 – session lifetime to subscriber <= 20 (ms)

Series in field 2 – number of sessions per subscriber >= 1500

We set the trigger conditions: average duration of SSH sessions to a subscriber is less than 20 ms and the number of SSH sessions for the subscriber is greater than 1500 for the analyzed period.

Error handling

In "If no errors" — no data

In "If error or timeout" — save last state

With this configuration, if there are no errors, no data is saved; if errors occur, information about suspicious activity is saved.

Actions

E-mail action

Click the "</>" icon to auto-fill the form

In the "To" field — specify the email address

With this setup, when the trigger fires an email with the notification details (ID, trigger name, status, link to the report — saved state) will be sent to the specified address

Notification

Click "</>" to auto-fill the form

Select notification type — "Warning"

This will create a notification in the SSG system

You can get a link to the report via the notifications menu

Select the notification Choose — "Details"

Follow the report link — the report will open in a new browser window.

HTTP action

Click "</>" to auto-fill the form. Choose the method most suitable for your ticket system and enter the URL.

Keep in mind — the numeric thresholds for sessions, incoming packets, etc., are given as averaged examples. Fine-tune thresholds based on your network specifics.