huntrule

Windows MSSQL Failed Logon (EventID 18456) From External Client IP

Alerts on MSSQL failed login attempts (Event 18456) from client IPs outside typical local/private ranges.

FreeReviewedSigma · Medium · v2
Product
windows
Service
application
Author
j4son (SigmaHQ), DRL 1.1
Published
2023-10-11
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Cred Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule identifies MSSQL authentication failures by matching Windows application events with EventID 18456 and a Provider name containing "MSSQL". It flags failed logon attempts where the client address is not within the listed local/private IP ranges, which may indicate credential-guessing or brute-force activity against an externally reachable SQL endpoint. It relies on Windows application log events that include the Provider name, EventID, and client address field (Data).

Reporting behind it

Related detections9 linkedT1110 — drag to rearrange
Malicious SQL Server - Brutforce Enumeration with Non Existing Users - Login (via application)
Malicious Brutforce Enumeration with Non Existing Users - Login (via security)
Malicious Brutforce Enumeration on Windows OpenSSH Server with Non Existing User (via security)
Malicious Brutforce on Windows OpenSSH Server with Valid Users (via security)
Malicious RDP Discovery Performed on Multiple Hosts (via rdp)
Possible SonicWall Credential Testing via userLogin Endpoint
Malicious Brutforce Enumeration with Unexisting Users - Kerberos (via security)
Suspicious JumpCloud Password Brute Force Followed by Success
AWS CloudTrail ConsoleLogin Failed authentication
Windows MSSQL Failed Logon (EventID 18456) From External Client IP
Pivot detection · T1110 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.