RE: Any reason not to use strcpy, strcat or scanf?

["Yvan Boily" <yboily () seccuris com>]

A valuable explanation of why not to use them can be found in Aleph One's
article "Smashing The Stack For Fun And Profit".

http://destroy.net/machines/security/P49-14-Aleph-One 

Understanding why buffer overruns are dangerous and how they can be
exploited helps significantly when trying to understand why it is important
to to make assumptions about the size of data being passed between function
calls.  I strongly recommending getting a copy Viega & McGraws book Building
Secure Software, http://www.buildingsecuresoftware.com/

This book is a very good resource for someone learning about software design
etc...

Yvan Boily

-----Original Message-----
From: Keller, Tim [mailto:Tim.Keller () stratus com] 
Sent: Wednesday, July 14, 2004 2:23 PM
To: Secbasics
Subject: RE: Any reason not to use strcpy, strcat or scanf?

A.V.,

Yeah.  The reason you shouldn't use these because they don't do any bounds
checking.  Thus you could have a situation where you've defined an 80
character array and then write a 180 characters into it, going off the end
of the variable and stomping on whatever is past it...

What you should use is strncpy and strncat.  These force you to specify that
you only copy or concatonate "n" bytes from the source into the destination.

Check out this site, it's got some very good info on what your interested
in.

http://www.dwheeler.com/secure-programs/Secure-Programs-HOWTO/dangers-c.html


-----Original Message-----
From: A.V. [mailto:pahalial.lists () gmail com]
Sent: Wednesday, July 14, 2004 7:00 AM
To: Secbasics
Subject: Any reason not to use strcpy, strcat or scanf?


Hi,

I was simply wondering after seeing the "blackhat audit" program sent
to F-D whether there was actually any reason not to use these
functions (strcpy/strcat/scanf) in your code. I mean, I understand why
you shouldn't use scanf to i.e. process user input, but other than
that? Some kind of unexpected behaviour or something?

Thanks,
A.V.

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