ID: 49687
Updated by: scott...@php.net
Reported By: sird at rckc dot at
-Status: Open
+Status: Feedback
Bug Type: *Unicode Issues
Operating System: *
PHP Version: 5.2.11
New Comment:
On a 16-bit processor an int might be 16-bit, if you can get PHP to
compile then well done :-)
Did you even try running the test code?
Previous Comments:
[2009-10-16 01:36:27] sird at rckc dot at
: ras...@php.net
It has come to my attention that this hasn't been fixed..
unsigned int has a size of 16 bits, don't take my word for it
http://www.acm.uiuc.edu/webmonkeys/book/c_guide/1.2.html
Section: 1.2.2 Variables
unsigned int16 bits
I just downloaded PHP 5.2.11, and I quote the code:
// php-5.2.11.tar.bz2/php-5.2.11/ext/xml/xml.c#558
PHPAPI char *xml_utf8_decode(// ...
{
int pos = len;
char *newbuf = emallo// ...
unsigned int c; // sizeof(unsigned int)==16 bits
char (*decoder)(unsig// ...
xml_encoding *enc = x// ...
// ...
// #580
c = (unsigned char)(*s);
if (c = 0xf0) { /* four bytes encoded, 21 bits */
if(pos-4 = 0) {
c = ((s[0]7)18) | ((s[1]63)12) | ((s[2]63)6) |
(s[3]63);
} else {
c = '?';
}
s += 4;
pos -= 4;
// ...
Also no checking at ALL is made on the leading bytes (they should be in
the form: 10xx , a check is very easy, to check if s[0] has the
correct form: you do an AND with 1100 and then compare it with 1000
.
s[0]0xC0==0x80
Also, Overlong UTF is not being taken care of, that's yeah, yet another
vulnerability.
Greetings!!
[2009-09-29 05:29:22] sird at rckc dot at
the rest is still dangerous.. eating chars without the 10xx is
against the spec, and overlong UTF.
[2009-09-29 04:56:08] ras...@php.net
there are several bugs in the code, one of them is that a variable
holding the value of the char is overflowed (trying to put 21 bits in
a
16 bits int)
That was fixed in 5.2.11
[2009-09-29 01:58:37] sird at rckc dot at
it is a PHP bug, the function is not decoding correctly, check the ppt
and the acunetix blog for details.
there are several bugs in the code, one of them is that a variable
holding the value of the char is overflowed (trying to put 21 bits in a
16 bits int), also the code is not checking if it is a valid unicode
char (reading unicode specification should explain it).
the example r...@80sec gave you was an overlong utf representation of a
single quote. that is forbidden by unicode, and should transform the
char to ?.
also, the code is not checking if the chars are valid UTF, so stuff
like: img alt=\x90 title= src=x:x onerror=alert(1)// are going to
be transformed to img alt=? title= src=x:x onerror=alert(1)//
this is a very serious vulnerability and there are several bugs in the
same function (there's even unreachable code).
you can check the implementation of utf by Mozilla or Webkit, they do
it right. dont use java as a reference since they are also flawed.
due to the fact that PHP is for web applications and utf is widely
used, and it allows an attacker to do all type of attacks (from sql
injection to xss) its imperative to fix that function.
Greetings!!
[2009-09-28 19:38:24] sjo...@php.net
Is this a bug in PHP or in scripts which do utf8_decode(addslashes())
instead of addslashes(utf8_decode())? What do you propose to solve this
bug?
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
http://bugs.php.net/49687
--
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