Securax Security Advisory #13 - When someone telnets to a unix system, the tty that will be assigned to him will be writable for any user on the system. However, when he is logged in, his tty will not be writable for all users. So if someone would write data to a tty that is currently used by someone who's logging in, that person won't be able to log in. Includes ttywrite.c proof of concept code.
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