Mysterious security hole

[eric.a.olson]

In article <JC.91Jun22234051 at raven.bu.edu> jc at raven.bu.edu (James Cameron) writes:
>>>>>> On 22 Jun 91 22:06:35 GMT, mcmahan at cs.unca.edu (Scott McMahan) said:
>
>Scott> In article <1991Jun21.203054.989 at serval.net.wsu.edu> yeidel at tomar.accs.wsu.edu (Joshua Yeidel) writes:
>>>The example of having something in / is bad for obvious reasons.  But 
>>>what about /tmp?  A script named say "la" (common type of "ls") which
>>>does a chmod 777 /, sends mail to the person and then echos 
>>>"la: Command not found" would do the job nicely. 
>>
>>Is /tmp in your path?  Why?
>
>Scott> I wondered that myself.
>
>
>Why were talking about '.' being in your path.  So, if your
>current directory is /tmp and even if '.' is last in your
>path....
>
>You figure out the trojan horse here...
>
>jc
    
    No, I thought we were talking about using *reasonable* security
    measures, especially when running as root.  Jamie Mason voiced
    my sentiments:

>	In fact only *ever* execute commands as root that you really
>*have to*.  Su to an appropriate, weaker, userid to do anything else.
>AND put "." last in the path, if at all.

    The scenarios posted by various individuals assume at least one
    of the following:
	1.  A system directory in root's PATH is left writeable
	2.  Root is foolish or inexperienced enough to do more
	    than what absolutely *requires* root privilege
	3.  Root is foolish or inexperienced enough to cd to do:
		cd dir; ls
	    rather than 
		ls dir
	    hmmph.   probably also does 'pwd' to make sure the 'cd' worked.

    I'm not advocating putting '.' in root's path.  I don't.  But that's
    because I fear unexpected consequences of running *any* random commands 
    as root, not because I fear that somebody might leave a trojan horse in
    a directory.