Potential External Linux SSH Brute Force Detected

Last updated a year ago on 2025-01-15

Created 3 years ago on 2022-09-14

About

Identifies multiple external consecutive login failures targeting a user account from the same source address within a short time interval. Adversaries will often brute force login attempts across multiple users with a common or known password, in an attempt to gain access to these accounts.

Tags

Domain: EndpointOS: LinuxUse Case: Threat DetectionTactic: Credential AccessLanguage: eql

Severity

low

Risk Score

MITRE ATT&CK™

Credential Access (TA0006)(external, opens in a new tab or window)

↳ Brute Force (T1110)(external, opens in a new tab or window)

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: Event Correlation Rule
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: filebeat-*logs-system.auth-*
Related Integrations: system(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗sequence by host.id, source.ip, user.name with maxspan=15s
  [ authentication where host.os.type == "linux" and 
   event.action in ("ssh_login", "user_login") and event.outcome == "failure" and
   not cidrmatch(source.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
       "192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32",
       "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4",
       "100.64.0.0/10", "192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", 
       "::1", "FE80::/10", "FF00::/8") ] with runs = 10

Install detection rules in Elastic Security

Detect Potential External Linux SSH Brute Force Detected in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).