The recent discussion about the Japanese encoded mails that
everyone received resulted in several comments being made about
the mail client one chooses to use.
I have just analyzed the message that supposedly "crashed" my
mailer and found out that PINE did not crash at all. What
happened is that the random garbage in the message contained a
CTRL-N character which the linux console interprets as the code
to switch to charset G1 from G0. CTRL-O changes back to G0.
So any console mail program would have exhibited the same
problem, and it is not a problem of the mailer crashing. It is
likely that other control codes can also be sent as well, and
that some code caused the console to react just like an ANSI bomb
back in the BBS days.
I have tested this out by sending emails containing individual
codes to myself and testing the results.
So, since any ^N echoed to the screen will change the active
charset, I have added "charset G1 iso01" to my rc.local. I've
tested this out and it appears to solve the problem for me.
This brings up the question though, is there a security concern
with ANSI bomb type of problems with the kernel console code? Is
there a way of disabling the charsets? I only need one charset,
and it would be nice to disable the feature without stripping the
code out of the kernel.
I'm going to explore further now to see if I can get an email
message to execute arbitrary code..
TTYL
-- Mike A. Harris Linux advocate Computer Consultant GNU advocate Capslock Consulting Open Source advocate... Our continuing mission: To seek out knowledge of C, to explore strange UNIX commands, and to boldly code where no one has man page 4.
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This archive was generated by hypermail 2b29 : Sun Jul 23 2000 - 21:00:17 EST