[cups.general] postscript exploits possible?

[Michael Sweet]

Adam Monsen wrote:
> (silly?) Quick question on using printer drivers with CUPS. Is it
> possible that a .PPD file could contain malicious code, and that CUPS
> could/would execute that to do something bad to the printer and/or the
> operating system?

To the printer, possibly, to the operating system, unlikely since
a) Ghostscript (the only real consumer of PostScript commands) is
run in a very restricted mode (no direct access to the filesystem)
and b) all filters run as a restricted user (typically "lp").

> For instance, if cupsd was running as root, could there be an "rm -rf
> /" or something in the .PPD, and if so would CUPS just execute that
> and trash the hard drive?

No.  The worst someone could do with the standard CUPS release
(assuming they did find a vulnerability in a filter) would be to
delete temporary files in /var/spool/cups/temp.  If you are running
on a Debian-based distro, your risks are somewhat higher because
they use a patch that runs everything as user "lp" so a filter could
remove CUPS configuration and spool files as well.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com