Updated Solaris users who enable telnet are about as secure as a fortress with a screen door, according to reports that claim cyber crooks can use the protocol to easily gain root access.
The Internet Storm Center is urging system administrators to disable or restrict telnet functionality to contain the zero-day vulnerability, which, according to center, affects only the most recent versions of Solaris and OpenSolaris.
Sun executives talk up secure Solaris at just about every turn. However, some simple tinkering with the OS's telnet user environment variable can give outsiders free reign with no authentication requirements. No special tools are required to exploit the vulnerability. Sans has long urged against the use of reusable clear-text passwords when administering telnet.
A Sun spokesman says the company has been able to verify the vulnerability and is in the process of testing a fix. He also says that by default telnet is disabled in Solaris 10, and users would have to follow a series of steps to enable it and even more to allow it to administer root privileges. Sun has long recommended Solaris SecureShell as a more secure alternative to telnet.
(A Solaris expert tells us telnet is turned off by default only in Update 3 of Solaris 10; Updates 1 and 2 enable telnet by default, although not with root capabilities, according to this person. Even without root privileges, attackers could nonetheless effect a fair amount of mischief.) ®