Re: PG16.1 security breach?

On Wed, Jun 12, 2024 at 3:57 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Ron Johnson <ronljohnsonjr(at)gmail(dot)com> writes:
> > On Wed, Jun 12, 2024 at 4:36 PM David G. Johnston <
> > david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
> >> I think my point is that a paragraph like the following may be a useful
> >> addition:
> >>
> >> If one wishes to remove the default privilege granted to public to
> execute
> >> all newly created procedures it is necessary to revoke that privilege
> for
> >> every superuser in the system
>
> > That seems... excessive.
>
> More to the point, it's wrong. Superusers have every privilege there
> is "ex officio"; we don't even bother to look at the catalog entries
> when considering a privilege check for a superuser. Revoking their
> privileges will accomplish nothing, and it does nothing about the
> actual source of the problem (the default grant to PUBLIC) either.
>

Apparently my forgetting the word "default" in front of privilege makes a
big difference in understanding/meaning.

Alter Default Privileges FOR postgres Revoke Execute on Functions From
PUBLIC;

That is what I meant, I was wrong in that I wrote permission instead of "d
If one wishes to remove the default privilege granted to public to execute
all newly created procedures it is necessary to revoke that [default]
privilege for
every superuser in the system.

The FOR postgres part is inferred, it matches the current role if omitted.

If I now create (or even if there already existed) a new superuser named
davidj and they create a function, the public pseudo-role will be able to
execute that function. You would first need to execute the above command,
substituting davidj for postgres, if you want to prevent that.

David J.