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remove kses from API docs, it is not used any more
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kses AUTHORS
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============
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* Ulf Harnhammar <metaur at users dot sourceforge dot net>
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main coder, project leader
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* Richard R. Vasquez, Jr. (contact him at http://www.chaos.org/contact/)
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coder (object-oriented kses)
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||||
* Simon Cornelius P. Umacob <simoncpu at users dot sourceforge dot net>
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tester
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Thanks to a lot of people who posted to the Bugtraq and Webappsec mailing lists
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about XSS or HTML filters. They gave us some valuable insights.
|
@ -1,340 +0,0 @@
|
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GNU GENERAL PUBLIC LICENSE
|
||||
Version 2, June 1991
|
||||
|
||||
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
|
||||
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||||
Everyone is permitted to copy and distribute verbatim copies
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@ -1,118 +0,0 @@
|
||||
kses ChangeLog
|
||||
==============
|
||||
|
||||
* 0.2.1
|
||||
|
||||
0.2.1 was released on the 29th of September 2003.
|
||||
It has the following changes:
|
||||
|
||||
|
||||
- There is now an additional version of kses, using the object-oriented
|
||||
paradigm. Thanks a lot to Richard R. Vasquez, Jr., who created it! Anyone
|
||||
who wants to make functional programming, logical programming or spaghetti
|
||||
programming versions of kses as well (or any other programming paradigm that
|
||||
you like), go ahead! All the people who like old procedural programming for
|
||||
web applications shouldn't despair, though, as both versions will be
|
||||
maintained with each release.
|
||||
|
||||
- kses now has some new attribute value checks: minlen, minval and valueless.
|
||||
See docs/attribute-value-checks for an explanation.
|
||||
|
||||
- For some reason, the Opera developers decided to make chr(173) a whitespace
|
||||
character in URL protocols, both when it occurs raw and in an entity. kses
|
||||
now handles this.
|
||||
|
||||
- The URL protocol whitelisting system now decodes entities before removing
|
||||
NULLs and whitespaces.
|
||||
|
||||
|
||||
* 0.2.0
|
||||
|
||||
0.2.0 was released on the 25th of July 2003.
|
||||
It has the following changes:
|
||||
|
||||
|
||||
- kses now supports checking of attribute values, and not just element names
|
||||
and attribute names. The attribute value checks that exist so far are
|
||||
'maxlen' (checks how long attribute values are, to avoid Buffer Overflows)
|
||||
and 'maxval' (checks how big an integer value is, to avoid Denial of Service
|
||||
attacks).
|
||||
|
||||
Buffer Overflows could both be a problem for WWW clients and different
|
||||
servers on the Internet that an HTML document links to. One example is
|
||||
<frame src="ftp://ftp.v1ct1m.com/AAAAAA..thousands_of_A's...">.
|
||||
|
||||
Denial of Service attacks can take the form of too big sizes of iframes or
|
||||
other things. One example is <iframe src="http://some.web.server/"
|
||||
width="20000" height="2000">, which makes some client machines completely
|
||||
overloaded.
|
||||
|
||||
- kses' old feature of removing "javascript:" from attribute values has been
|
||||
improved. It now has a whole system for white listing of URL protocols, so
|
||||
you can specify that it's acceptable with http:, https:, ftp: and gopher:,
|
||||
but no other protocols in attribute values. The system tries pretty hard to
|
||||
do the right thing with whitespace, upper/lower case, HTML entities
|
||||
("javascript:") and repeated entries ("javascript:javascript:alert(57)").
|
||||
|
||||
- kses now supports both HTML and XHTML code, by allowing " /" at the end of
|
||||
tags.
|
||||
|
||||
- kses now removes Netscape 4's JavaScript entities, having the form
|
||||
"&{alert(57)};". They don't even seem to work on all versions of Netscape 4,
|
||||
but for completeness' sake it seemed like a good feature to add.
|
||||
|
||||
- A bug with NULLs in javascript: URLs was fixed.
|
||||
(Reported by Simon Cornelius P. Umacob - thanks!)
|
||||
|
||||
- As a nice side effect of the white listing of URL protocols, kses now also
|
||||
normalizes all HTML entities in documents. It will change HTML code with bad
|
||||
entities to the right form, for example "AT&T" will be converted to
|
||||
"AT&T" and "<a href='lyrics.php?band=ladytron&lyrics=playgirl'>" will be
|
||||
converted to "<a href='lyrics.php?band=ladytron&lyrics=playgirl'>".
|
||||
":" will be converted to ":", "&#XYZZY;" will be converted to
|
||||
"&#XYZZY;", "ä!;" will be converted to "&auml!;" and so on.
|
||||
|
||||
As shown above, it will process HTML entities that it doesn't understand.
|
||||
It will also deal with too big numbers in numeric HTML entities, which is
|
||||
helpful as many browsers seem to wrap them around at 2 ** 32, so the
|
||||
characters 58, 58 + (2 ** 32), 58 + (2 ** 64) etcetera are all colons to the
|
||||
web browser.
|
||||
|
||||
- You can now use upper case letters in your $allowed_html array, in element
|
||||
names, attribute names and attribute value check names. Version 0.1.0
|
||||
required everything in that array to be in lower case, but that's not
|
||||
necessary any more. You can also use upper case letters in
|
||||
$allowed_protocols.
|
||||
|
||||
- The "Really malformed thing" bug from the TODO file was fixed.
|
||||
It used to convert this string:
|
||||
x > 5 <a href="blah">
|
||||
to:
|
||||
x > 5 <a href="blah">
|
||||
and now it converts it to:
|
||||
x > 5 <a href="blah">
|
||||
|
||||
- The "Weird malformed thing" bug from the TODO file was fixed.
|
||||
It used to convert this string:
|
||||
<a href="5 href=6>
|
||||
to:
|
||||
<a href="6">
|
||||
because of the way kses restarts after a parse error in kses_hair(). Now it
|
||||
converts it to:
|
||||
<a>
|
||||
|
||||
- A problem with slashes in HTML tags was fixed.
|
||||
|
||||
- examples/filter.php used to use $SCRIPT_NAME, which doesn't work on
|
||||
Windows.
|
||||
(Reported by Simon Cornelius P. Umacob - thanks!)
|
||||
|
||||
- kses now allows dashes in attribute names, for things like
|
||||
<meta http-equiv=..>.
|
||||
|
||||
|
||||
* 0.1.0, first public version
|
||||
|
||||
0.1.0 was released on the 9th of June 2003.
|
||||
It was announced on three security related mailing lists on Friday the 13th
|
||||
of June (nothing bad happened to it though).
|
@ -1,203 +0,0 @@
|
||||
kses 0.2.1 README [kses strips evil scripts!]
|
||||
=================
|
||||
|
||||
|
||||
* INTRODUCTION *
|
||||
|
||||
|
||||
Welcome to kses - an HTML/XHTML filter written in PHP. It removes all unwanted
|
||||
HTML elements and attributes, no matter how malformed HTML input you give it.
|
||||
It also does several checks on attribute values. kses can be used to avoid
|
||||
Cross-Site Scripting (XSS), Buffer Overflows and Denial of Service attacks,
|
||||
among other things.
|
||||
|
||||
The program is released under the terms of the GNU General Public License. You
|
||||
should look into what that means, before using kses in your programs. You can
|
||||
find the full text of the license in the file COPYING.
|
||||
|
||||
|
||||
* FEATURES *
|
||||
|
||||
|
||||
Some of kses' current features are:
|
||||
|
||||
* It will only allow the HTML elements and attributes that it was explicitly
|
||||
told to allow.
|
||||
|
||||
* Element and attribute names are case-insensitive (a href vs A HREF).
|
||||
|
||||
* It will understand and process whitespace correctly.
|
||||
|
||||
* Attribute values can be surrounded with quotes, apostrophes or nothing.
|
||||
|
||||
* It will accept valueless attributes with just names and no values (selected).
|
||||
|
||||
* It will accept XHTML's closing " /" marks.
|
||||
|
||||
* Attribute values that are surrounded with nothing will get quotes to avoid
|
||||
producing non-W3C conforming HTML
|
||||
(<a href=http://sourceforge.net/projects/kses> works but isn't valid HTML).
|
||||
|
||||
* It handles lots of types of malformed HTML, by interpreting the existing
|
||||
code the best it can and then rebuilding new code from it. That's a better
|
||||
approach than trying to process existing code, as you're bound to forget about
|
||||
some weird special case somewhere. It handles problems like never-ending
|
||||
quotes and tags gracefully.
|
||||
|
||||
* It will remove additional "<" and ">" characters that people may try to
|
||||
sneak in somewhere.
|
||||
|
||||
* It supports checking attribute values for minimum/maximum length and
|
||||
minimum/maximum value, to protect against Buffer Overflows and Denial of
|
||||
Service attacks against WWW clients and various servers. You can stop
|
||||
<iframe src= width= height=> from having too high values for width and height,
|
||||
for instance.
|
||||
|
||||
* It has got a system for whitelisting URL protocols. You can say that
|
||||
attribute values may only start with http:, https:, ftp: and gopher:, but no
|
||||
other URL protocols (javascript:, java:, about:, telnet:..). The functions that
|
||||
do this work handle whitespace, upper/lower case, HTML entities
|
||||
("javascript:") and repeated entries ("javascript:javascript:alert(57)").
|
||||
It also normalizes HTML entities as a nice side effect.
|
||||
|
||||
* It removes Netscape 4's JavaScript entities ("&{alert(57)};").
|
||||
|
||||
* It handles NULL bytes and Opera's chr(173) whitespace characters.
|
||||
|
||||
* There is both a procedural version and an object-oriented version of kses.
|
||||
|
||||
|
||||
* USE IT *
|
||||
|
||||
|
||||
It's very easy to use kses in your own PHP web application! Basic usage looks
|
||||
like this:
|
||||
|
||||
|
||||
<?php
|
||||
|
||||
include 'kses.php';
|
||||
|
||||
$allowed = array('b' => array(),
|
||||
'i' => array(),
|
||||
'a' => array('href' => 1, 'title' => 1),
|
||||
'p' => array('align' => 1),
|
||||
'br' => array());
|
||||
|
||||
$val = $_POST['val'];
|
||||
if (get_magic_quotes_gpc())
|
||||
$val = stripslashes($val);
|
||||
# You must strip slashes from magic quotes, or kses will get confused.
|
||||
|
||||
$val = kses($val, $allowed); # The filtering takes place here.
|
||||
|
||||
# Do something with $val.
|
||||
|
||||
?>
|
||||
|
||||
|
||||
This definition of $allowed means that only the elements B, I, A, P and BR are
|
||||
allowed (along with their closing tags /B, /I, /A, /P and /BR). B, I and BR
|
||||
may not have any attributes. A may only have the attributes HREF and TITLE,
|
||||
while P may only have the attribute ALIGN. You can list the elements and
|
||||
attributes in the array in any mixture of upper and lower case. kses will also
|
||||
recognize HTML code that uses both lower and upper case.
|
||||
|
||||
It's important to select the right allowed attributes, so you won't open up
|
||||
an XSS hole by mistake. Some important attributes that you mustn't allow
|
||||
include but are not limited to: 1) style, and 2) all intrinsic events
|
||||
attributes (onMouseOver and so on, on* really). I'll write more about this in
|
||||
the documentation that will be distributed with future versions of kses.
|
||||
|
||||
It's also important to note that kses' HTML input must be cleaned of all
|
||||
slashes coming from magic quotes. If the rest of your code requires these
|
||||
slashes to be present, you can always add them again after calling kses with
|
||||
a simple addslashes() call.
|
||||
|
||||
You should take a look at the documentation in the docs/ directory and the
|
||||
examples in the examples/ directory, to get more information on how to use
|
||||
kses. The object-oriented version of kses is also worth checking out, and it's
|
||||
included in the oop/ directory.
|
||||
|
||||
|
||||
* UPGRADING FROM 0.1.0 OR 0.2.0 TO 0.2.1 *
|
||||
|
||||
|
||||
kses 0.2.1 is backwards compatible with 0.1.0 and 0.2.0, so upgrading should
|
||||
just be a matter of using a new version of kses.php instead of an old one!
|
||||
|
||||
When you're ready to start using 0.2.1's new features, you can read about them
|
||||
in the files in the docs/ directory. The ChangeLog also summarizes the new
|
||||
features in this release.
|
||||
|
||||
|
||||
* NEW VERSIONS, MAILING LISTS AND BUG REPORTS *
|
||||
|
||||
|
||||
If you want to download new versions, subscribe to the kses-general mailing
|
||||
list or even take part in the development of kses, we refer you to its
|
||||
homepage at http://sourceforge.net/projects/kses . New developers and beta
|
||||
testers are more than welcome!
|
||||
|
||||
If you have any bug reports, suggestions for improvement or simply want to tell
|
||||
us that you use kses for some project, feel free to post to the kses-general
|
||||
mailing list. If you have found any security problems (particularly XSS,
|
||||
naturally) in kses, please contact Ulf privately at metaur at users dot
|
||||
sourceforge dot net so he can correct it before you or someone else tells the
|
||||
public about it.
|
||||
|
||||
(No, it's not a security problem in kses if some program that uses it allows a
|
||||
bad attribute, silly. If kses is told to accept the element body with the
|
||||
attributes style and onLoad, it will accept them, even if that's a really bad
|
||||
idea, securitywise.)
|
||||
|
||||
|
||||
* OTHER HTML FILTERS *
|
||||
|
||||
|
||||
Here are the other stand-alone, open source HTML filters that we currently know
|
||||
of:
|
||||
|
||||
* XSS filter for PHP4 - the filter from Squirrelmail
|
||||
PHP
|
||||
Konstantin Riabitsev
|
||||
http://www.mricon.com/html/phpfilter.html
|
||||
|
||||
* HTML::StripScripts and related CPAN modules
|
||||
Perl
|
||||
Nick Cleaton
|
||||
http://search.cpan.org/perldoc?HTML%3A%3AStripScripts
|
||||
|
||||
There are also a lot of HTML filters that were written specifically for some
|
||||
program. Some of them are better than others.
|
||||
|
||||
Please write to the kses-general mailing list if you know of any other
|
||||
stand-alone, open-source filters.
|
||||
|
||||
|
||||
* DEDICATION *
|
||||
|
||||
|
||||
kses 0.2.1 is dedicated to Mischa the cat.
|
||||
|
||||
|
||||
* MISC *
|
||||
|
||||
|
||||
The kses code is based on an HTML filter that Ulf wrote on his own back in 2002
|
||||
for the open-source project Gnuheter ( http://savannah.nongnu.org/projects/
|
||||
gnuheter ). Gnuheter is a fork from PHP-Nuke. The HTML filter has been
|
||||
improved a lot since then.
|
||||
|
||||
To stop people from having sleepless nights, we feel the urgent need to state
|
||||
that kses doesn't have anything to do with the KDE project, despite having a
|
||||
name that starts with a K.
|
||||
|
||||
In case someone was wondering, Ulf is available for kses-related consulting.
|
||||
|
||||
Finally, the name kses comes from the terms XSS and access. It's also a
|
||||
recursive acronym (every open-source project should have one!) for "kses
|
||||
strips evil scripts".
|
||||
|
||||
|
||||
// Ulf and the kses gang, September 2003
|
@ -1,30 +0,0 @@
|
||||
kses TODO
|
||||
=========
|
||||
|
||||
* remove stuff in between <script>..</script> and <style>..</style>
|
||||
|
||||
* more attribute value checks
|
||||
|
||||
* more types of hooks
|
||||
|
||||
* return array of removed elements and attributes
|
||||
|
||||
* give the option of turning unacceptable elements to entities instead of
|
||||
removing them (and turn unacceptable attributes to their own tag, which is
|
||||
then turned to entities?) .. perhaps turn to comments as well?
|
||||
|
||||
* XHTML tags of the style <br/> instead of <br />
|
||||
This is related to a small bug with <a href="blah />
|
||||
Solution: rewrite parser.
|
||||
|
||||
* ">" in HTML tags
|
||||
<img src="blah.gif" alt="x > 5">
|
||||
Not very important, but..
|
||||
|
||||
* lots of testing
|
||||
|
||||
* write better documentation
|
||||
|
||||
* feedback from users
|
||||
|
||||
* create a nice homepage (any volunteers?)
|
@ -1,68 +0,0 @@
|
||||
kses attribute value checks
|
||||
===========================
|
||||
|
||||
As you've probably already read in the README file, an $allowed_html array
|
||||
normally looks like this:
|
||||
|
||||
$allowed = array('b' => array(),
|
||||
'i' => array(),
|
||||
'a' => array('href' => 1,
|
||||
'title' => 1),
|
||||
'p' => array('align' => 1),
|
||||
'br' => array());
|
||||
|
||||
This sets what elements and attributes are allowed.
|
||||
|
||||
From kses 0.2.0, you can also perform some checks on the attribute values. You
|
||||
do it like this:
|
||||
|
||||
$allowed = array('b' => array(),
|
||||
'i' => array(),
|
||||
'a' => array('href' =>
|
||||
array('maxlen' => 100),
|
||||
'title' => 1),
|
||||
'p' => array('align' => 1),
|
||||
'font' => array('size' =>
|
||||
array('maxval' => 20)),
|
||||
'br' => array());
|
||||
|
||||
This means that kses should perform the maxlen check with the value 100 on the
|
||||
<a href=> value, as well as the maxval check with the value 20 on the <font
|
||||
size=> value.
|
||||
|
||||
The currently implemented checks (with more to come) are 'maxlen', 'maxval',
|
||||
'minlen', 'minval' and 'valueless'.
|
||||
|
||||
'maxlen' checks that the length of the attribute value is not greater than the
|
||||
given value. It is helpful against Buffer Overflows in WWW clients and various
|
||||
servers on the Internet. In my example above, it would mean that
|
||||
"<a href='ftp://ftp.v1ct1m.com/AAAA..thousands_of_A's...'>" wouldn't be
|
||||
accepted.
|
||||
|
||||
Of course, this problem is even worse if you put that long URL in a <frame>
|
||||
tag instead, so the WWW client will fetch it automatically without a user
|
||||
having to click it.
|
||||
|
||||
'maxval' checks that the attribute value is an integer greater than or equal to
|
||||
zero, that it doesn't have an unreasonable amount of zeroes or whitespace (to
|
||||
avoid Buffer Overflows), and that it is not greater than the given value. In
|
||||
my example above, it would mean that "<font size='20'>" is accepted but
|
||||
"<font size='21'>" is not. This check helps against Denial of Service attacks
|
||||
against WWW clients.
|
||||
|
||||
One example of this DoS problem is <iframe src="http://some.web.server/"
|
||||
width="20000" height="2000">, which makes some client machines completely
|
||||
overloaded.
|
||||
|
||||
'minlen' and 'minval' works the same as 'maxlen' and 'maxval', except that they
|
||||
check for minimum lengths and values instead of maximum ones.
|
||||
|
||||
'valueless' checks if an attribute has a value (like <a href="blah">) or not
|
||||
(<option selected>). If the given value is a "y" or a "Y", the attribute must
|
||||
not have a value to be accepted. If the given value is an "n" or an "N", the
|
||||
attribute must have a value. Note that <a href=""> is considered to have a
|
||||
value, so there's a difference between valueless attributes and attribute
|
||||
values with the length zero.
|
||||
|
||||
You can combine more than one check, by putting one after the other in the
|
||||
inner array.
|
@ -1,7 +0,0 @@
|
||||
kses hooks
|
||||
==========
|
||||
|
||||
Sometimes you want to perform one more action on all data that kses will
|
||||
filter. There is a special function for that purpose called kses_hook(). kses
|
||||
calls it from its main function kses(), so if you insert some code in
|
||||
kses_hook(), it will always be called to change all data that kses sees.
|
@ -1,15 +0,0 @@
|
||||
kses whitelisted URL protocols
|
||||
==============================
|
||||
|
||||
From kses 0.2.0, it has a function that checks all attribute values for URL
|
||||
protocols and only allows the protocols given in a whitelist.
|
||||
|
||||
If you call kses the old way with two parameters - a string and an
|
||||
$allowed_html array - it will take its own default array, which whitelists the
|
||||
protocols http, https, ftp, news, nntp, telnet, gopher and mailto. Pretty
|
||||
reasonable, but anyone who wants to change it just calls the kses() function
|
||||
with a third parameter, like this:
|
||||
|
||||
$string = kses($string, $allowed_html, array('http', 'https'));
|
||||
|
||||
Note that you shouldn't include any colon after http or other protocol names.
|
Loading…
Reference in New Issue
Block a user