GEN:SID 1:712
Message TELNET ld_library_path
Summary This event is generated when an attempt is made to set an environment
variable in a Telnet session to a server.
Impact Unauthorized superuser access.
Detailed Information This event is generated when an attempt is made to use the environment
variable ld_library_path in a Telnet session.
Affected Systems Telnet servers.
Attack Scenarios An attacker can attempt to set the environment variable ld_library_path
and then attempt to exploit a known vulnerability in some SunOS based
systems.
Ease of Attack Simple
Corrective Action Use ssh as an alternative to Telnet

Block inbound telnet access if it is not required.
Additional References Bugtraq:
http://www.securityfocus.com/bid/43
Rule References arachnids: 367
bugtraq: 459
cve: 1999-0073