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TCP 1434

ProtocolTCP
Port1434
LabelsMicrosoft SQL Server database management system (MSSQL) monitor

Synopsis

  • Microsoft SQL Server: the Dedicated Administrator Connection (DAC) listens on TCP port 1434 for the default SQL Server instance, used for emergency admin access (e.g., sqlcmd -A or SSMS with the ADMIN:ServerName prefix).
  • Legacy Microsoft SQL Server Monitor service (ms-sql-m) also used TCP 1434 in SQL Server 7.0/2000-era installations and tools, and may still be seen on older Windows servers.
  • Associated exploitation: Port 1434 is infamous due to the 2003 SQL Slammer worm, which exploited a buffer overflow in the SQL Server Resolution Service on UDP 1434 (not TCP), causing widespread outages.

Observed activity

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