procmail
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Re: Preventing execution of arbitrary programs

1997-05-13 13:18:00
On Mon, 12 May 1997, Eric Daniel wrote:

 1) Assuming the pipe action is disabled, can I be sure that procmail does not
provide any other way of executing commands?

One thing might be to put your mail hub on a machine which is 
binary-incompatible with the workstations on your network. It will
make it that much harder for users to compile programs to even *try* to
run if they don't know what platform they are compiling for. Hee hee hee.

Another thing you should see if you can do is modify the procmail source 
(note: I haven't bothered to do this, because I don't work for an 
educational institution ;-)  so that it immediately sets DROPPRIVS as
it reads in a users .procmailrc - that way, if they execute any programs
they won't have any special priviledges.

You might also want to play some games with /bin/sh on that machine so they
can't run shell scripts either.. (even if they talk procmail into 
letting them). While I know these aren't really the solutions you're looking 
for, they are an interesting angle at even more marginally increasing 
system security.

--
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