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Re: Smashing the Stack: prevention?
From: shields () CROSSLINK NET (Michael Shields)
Date: Mon, 28 Apr 1997 19:38:33 -0000
1. 'you gotta change the code'
This one is obvious; people must change their SUID programs'
source code to avoid nasty things like gets() sprintf() strcat() and
strcpy() using things like fgets() strncat() strncpy() as substitutes.
(there are many more 'problem' functions, i'm only listing a few here).
Any unbounded byte copying is suspect to buffer overruns, and needs to
be examined and changed. The drawbacks are obvious, thousands of lines
of source need to be changed/examined, re-written.
However, it's important to remember that such auditing buys you not
just a secure program but a robust program as well. So it is
something you would want to do anyway, even if the programs were not
suid. The security issue just gives it urgency.
Security and robustness really go hand in hand -- they both involve
thinking about the ranges of allowable inputs and responses, and
limiting them so undesirable responses are not produced.
- Sun Security Bulletin #00139, (continued)