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NetBIOS
Service

NetBIOS

Windows legacy naming

:137 :138 :139 3 guides 2 phases
1 min read Updated: Jul 13, 2026

What is NetBIOS?
NetBIOS provides legacy Windows naming and session services, commonly tied to SMB discovery and access.

Common security issues

  • Hostname and domain or workgroup information disclosure

  • SMB access over 139 when 445 is restricted

  • Legacy protocol exposure enabling easier network reconnaissance

  • Weak segmentation around Windows file-sharing infrastructure

Enumeration

Pull hostnames, domain names, and role hints via NetBIOS name tables

2

NetBIOS Session Enumeration

Enumerate active NetBIOS sessions over TCP/445 to identify logged-in users, remote hosts, and active connections using tools like nbtstat and enum4linux.

Mar 30, 2026 • 3 min read

Vulnerability Discovery

Guides on finding info leaks via NetBIOS enumeration

1