Re: PATH and security

[Jim Meyering]

Bruno Haible <address@hidden> wrote:

> Jim Meyering wrote:
>> If security isn't enough of an argument, you can consider this yet another
>> reason not to put "." early in your PATH.  Please consider removing
>> "." from your PATH altogether.  Yes, that does make for some small amount
>> of extra typing (you have to prefix certain commands with "./"), but
>> that is a small price to pay for the reduced risk of mishap.
>> [Sorry to harp on this again, but I wouldn't want readers to get the
>>  impression that it's ok to have "." *anywhere* in PATH, much less
>>  near the beginning. ]
>
> The only security argument I've seen so far against "." in PATH is that
> every user, at some point in time, does things like
>   $ cd /tmp
>   $ ls -l
> and another user on the same machine may have stored a malicious program
> at /tmp/ls.
>
> A similar argument holds for group-writable directories on machines where
> you don't trust all users of the same group.
>
> But when you are on a LAN where you trust all users, or on a firewalled
> machine where you are the only user and even your own sysadmin, I see no
> point in reducing the PATH. - If you trust everyone in your house, and have
> a lock at the door of your house, would you also lock your bedroom's door
> at night?

Habits are habits.
If I acquire habits that are safe only in a few
protected environments, what's to prevent that often-safe
behavior from leaking into an environment where it's no longer safe?
I prefer to maintain safe habits.

Besides, I recognize that no system is immune from risk.
I.e., a bug in my browser may allow malicious code to create
that /tmp/ls file you mentioned.