Generic protection in PHP

[RoMaNSoFt <r0man () phreaker net>]

 Hi vuln-devels,

 I've written a little and compact PHP routine intended to protect PHP
applications in a generic way. The idea is to call the routine at the
very beginning of any .php file so it could parse *all* global
variables. I've tried to make the routine as generic as possible. It
should work ok on every PHP version, with or without
'register_globals' enabled (I've only tested on PHP 4.2.2, though).
The possible cost of performance perhaps should be take into account
on servers with heavy load. But I think it's worth your while having a
try with it :-)

 I've chosen the following cleaning method:
addslashes(htmlentities($var));

 The reason for that is:
- 1st, all html entities are re-written in a secure way, so no html
injection is possible. This tries to fight against cross-site
scripting bugs.
- 2nd, some dangerous chars (like "quotes" char) are secured. This is
for avoiding SQL injection problems.

 As a side effect, data to be saved in a database will be stored in an
html'ized form (for instance, a char like "á" will be stored as
"á"). It could be an advantage (perhaps it could fix some
problems with languages and charsets in databases, since we're
removing strange characters) or a disadvantage (lost of performance,
since we're using more characters to "encode" a single [special]
char). Perhaps this is something you can perfectly live with.

 Any feedback would also be greatly appreciated (this should be sent
to me, not to the whole mailing-list).


  /* Sanitized Vars Routine by RoMaNSoFt (r0man () phreaker net) */
  function sanitize_vars() {

    foreach ($GLOBALS as $var => $value) {
      if (is_array($value)) {
        foreach ($value as $i => $j) {
          $GLOBALS[$var][$i] = addslashes(htmlentities($j));
        }
      } else {
        $GLOBALS[$var] = addslashes(htmlentities($value));
      }
    }

  }



+ Madrid, 2002.10.28 +
 --Roman

PS: Regards to the iZhal crew (publicidad subliminal incluida :-))

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