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Denicomp Winsock RSHD/NT Standard Error Denial of Service Vulnerability

Winsock RSHD/NT is a Remote Shell Daemon for Windows NT and Windows 2000. It uses the standard Unix rsh and rcp commands. rsh (ie "remote shell") allows the execution of a non-interactive program on another system running the server component, 'rshd'. The daemon listens for connections coming from an rsh command through TCP/IP, and, on receiving a connection, validates access and executes the specified program.

Upon connecting to the daemon, rsh will supply a port number for the daemon to send standard error data. If the port number specified is invalid, Winsock RSHD/NT will attempt to connect to the invalid port and all port numbers below 1024 (including negative port numbers). Potentially consuming CPU resources and leading to a denial of service.