«By redefining the `showpage' operator which is contained in every
PostScript document to print the current page, an attacker can hook in
there and execute her our own PostScript code. Long term redefinition
(until the device is restarted) is possible by prepending the
`startjob'/`exitserver' operators.»
Then all bets are off, any print job can be captured, altered, stored, denied, etc.