Re: stuff in ~/bin won't run
On 2009-01-13 20:28 +0100, Daryl Styrk wrote:
> "This is unsafe because you are trusting that your own version of the
> more command works properly. But it is also risky for a more important
> reason: system security. If your PATH is set up in this way, you leave
> open a "hole" that is well known to computer crackers and mischief
> makers: they can install "Trojan horses" and do other things to steal
> files or do damage."
The book in general is not so bad, but this statement, in fact the whole
paragraph, is just nonsense.
> There is a senerio that goes on to detail how a user with a suid script
> in their personal bin directory before a public bin. Creating a Trojan
> that looks for a common utility such as grep..
For one thing, the suid bit is ignored for scripts on Linux. And your
~/bin directory should never be writable by other people.
> The example script..
> "cp /bin/bash filenamechown root filenamechmod 4755 filename/bin/grep
> "$@"rm ~/bin/grep"
Will just not work, unless the user executing the script is root.
> "Sits back and waits for the user to run the suid shell script—which
> calls the Trojan horse, which in turn creates the suid shell and then
> self-destructs."
>
> If you have the book I'm looking at chapter 10. 10.3.2 to be exact.
Do you have the third edition? The second edition which I own does not
have sections inside the chapters numbered.
Sven
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