㊙️ AntiXSS

"Cross-site scripting (XSS) is a type of computer security vulnerability typically found in Web applications. XSS enables attackers to inject client-side script into Web pages viewed by other users. A cross-site scripting vulnerability may be used by attackers to bypass access controls such as the same origin policy. Cross-site scripting carried out on websites accounted for roughly 84% of all security vulnerabilities documented by Symantec as of 2007." - http://en.wikipedia.org/wiki/Cross-site_scripting

DEMO:

http://anti-xss-demo.suckup.de/

NOTES:

Use filter_input() - don't use GLOBAL-Array (e.g. $_SESSION, $_GET, $_POST, $_SERVER) directly
Use html-sanitizer or HTML Purifier if you need a more configurable solution
Add "Content Security Policy's" -> Introduction to Content Security Policy
DO NOT WRITE YOUR OWN REGEX TO PARSE HTML!
READ THIS TEXT -> XSS (Cross Site Scripting) Prevention Cheat Sheet
TEST THIS TOOL -> Zed Attack Proxy (ZAP)

Install via "composer require"

composer require voku/anti-xss

Usage:

use voku\helper\AntiXSS;

require_once __DIR__ . '/vendor/autoload.php'; // example path

$antiXss = new AntiXSS();

Example 1: (HTML Character)

$harm_string = "Hello, i try to <script>alert('Hack');</script> your site";
$harmless_string = $antiXss->xss_clean($harm_string);

// Hello, i try to alert&#40;'Hack'&#41;; your site

Example 2: (Hexadecimal HTML Character)

$harm_string = "<IMG SRC=&#x6A&#x61&#x76&#x61&#x73&#x63&#x72&#x69&#x70&#x74&#x3A&#x61&#x6C&#x65&#x72&#x74&#x28&#x27&#x58&#x53&#x53&#x27&#x29>";
$harmless_string = $antiXss->xss_clean($harm_string);
    
// <IMG >

Example 3: (Unicode Hex Character)

$harm_string = "<a href='&#x2000;javascript:alert(1)'>CLICK</a>";
$harmless_string = $antiXss->xss_clean($harm_string);
    
// <a >CLICK</a>

Example 4: (Unicode Character)

$harm_string = "<a href=\"\u0001java\u0003script:alert(1)\">CLICK<a>";
$harmless_string = $antiXss->xss_clean($harm_string);
    
// <a >CLICK</a>

Example 5.1: (non Inline CSS)

$harm_string = '<li style="list-style-image: url(javascript:alert(0))">';
$harmless_string = $antiXss->xss_clean($harm_string);

// <li >

Example 5.2: (with Inline CSS)

$harm_string = '<li style="list-style-image: url(javascript:alert(0))">';
$antiXss->removeEvilAttributes(array('style')); // allow style-attributes
$harmless_string = $antiXss->xss_clean($harm_string);

// <li style="list-style-image: url(alert&#40;0&#41;)">

Example 6: (check if an string contains a XSS attack)

$harm_string = "\x3cscript src=http://www.example.com/malicious-code.js\x3e\x3c/script\x3e";
$harmless_string = $antiXss->xss_clean($harm_string);

// 

$antiXss->isXssFound(); 

// true

Example 7: (allow e.g. iframes)

$harm_string = "<iframe width="560" onclick="alert('xss')" height="315" src="https://www.youtube.com/embed/foobar?rel=0&controls=0&showinfo=0" frameborder="0" allowfullscreen></iframe>";

$antiXss->removeEvilHtmlTags(array('iframe'));

$harmless_string = $antiXss->xss_clean($harm_string);

// <iframe width="560"  height="315" src="https://www.youtube.com/embed/foobar?rel=0&controls=0&showinfo=0" frameborder="0" allowfullscreen></iframe>

Unit Test:

Composer is a prerequisite for running the tests.

composer install

The tests can be executed by running this command from the root directory:

./vendor/bin/phpunit

AntiXss methods

addDoNotCloseHtmlTags	addEvilAttributes	addEvilHtmlTags	addNeverAllowedCallStrings
addNeverAllowedJsCallbackRegex	addNeverAllowedOnEventsAfterwards	addNeverAllowedRegex	addNeverAllowedStrAfterwards
isXssFound	removeDoNotCloseHtmlTags	removeEvilAttributes	removeEvilHtmlTags
removeNeverAllowedCallStrings	removeNeverAllowedJsCallbackRegex	removeNeverAllowedOnEventsAfterwards	removeNeverAllowedRegex
removeNeverAllowedStrAfterwards	setReplacement	setStripe4byteChars	xss_clean

addDoNotCloseHtmlTags(string[] $strings): $this

↑ Add some strings to the "_do_not_close_html_tags"-array.

Parameters:

string[] $strings

Return:

$this

addEvilAttributes(string[] $strings): $this

↑ Add some strings to the "_evil_attributes"-array.

Parameters:

string[] $strings

Return:

$this

addEvilHtmlTags(string[] $strings): $this

↑ Add some strings to the "_evil_html_tags"-array.

Parameters:

string[] $strings

Return:

$this

addNeverAllowedCallStrings(string[] $strings): $this

↑ Add some strings to the "_never_allowed_call_strings"-array.

Parameters:

string[] $strings

Return:

$this

addNeverAllowedJsCallbackRegex(string[] $strings): $this

↑ Add some strings to the "_never_allowed_js_callback_regex"-array.

Parameters:

string[] $strings

Return:

$this

addNeverAllowedOnEventsAfterwards(string[] $strings): $this

↑ Add some strings to the "_never_allowed_on_events_afterwards"-array.

Parameters:

string[] $strings

Return:

$this

addNeverAllowedRegex(string[] $strings): $this

↑ Add some strings to the "_never_allowed_regex"-array.

Parameters:

string[] $strings

Return:

$this

addNeverAllowedStrAfterwards(string[] $strings): $this

↑ Add some strings to the "_never_allowed_str_afterwards"-array.

Parameters:

string[] $strings

Return:

$this

isXssFound(): bool|null

↑ Check if the "AntiXSS->xss_clean()"-method found an XSS attack in the last run.

Parameters: nothing

Return:

bool|null <p>Will return null if the "xss_clean()" wasn't running at all.</p>

removeDoNotCloseHtmlTags(string[] $strings): $this

↑ Remove some strings from the "_do_not_close_html_tags"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeEvilAttributes(string[] $strings): $this

↑ Remove some strings from the "_evil_attributes"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeEvilHtmlTags(string[] $strings): $this

↑ Remove some strings from the "_evil_html_tags"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeNeverAllowedCallStrings(string[] $strings): $this

↑ Remove some strings from the "_never_allowed_call_strings"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeNeverAllowedJsCallbackRegex(string[] $strings): $this

↑ Remove some strings from the "_never_allowed_js_callback_regex"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeNeverAllowedOnEventsAfterwards(string[] $strings): $this

↑ Remove some strings from the "_never_allowed_on_events_afterwards"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeNeverAllowedRegex(string[] $strings): $this

↑ Remove some strings from the "_never_allowed_regex"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

removeNeverAllowedStrAfterwards(string[] $strings): $this

↑ Remove some strings from the "_never_allowed_str_afterwards"-array.

WARNING: Use this method only if you have a really good reason.

Parameters:

string[] $strings

Return:

$this

setReplacement(string $string): $this

↑ Set the replacement-string for not allowed strings.

Parameters:

string $string

Return:

$this

setStripe4byteChars(bool $bool): $this

↑ Set the option to stripe 4-Byte chars.

INFO: use it if your DB (MySQL) can't use "utf8mb4" -> preventing stored XSS-attacks

Parameters:

bool $bool

Return:

$this

xss_clean(string|string[] $str): string|string[]

↑ XSS Clean

Sanitizes data so that "Cross Site Scripting" hacks can be prevented. This method does a fair amount of work but it is extremely thorough, designed to prevent even the most obscure XSS attempts. But keep in mind that nothing is ever 100% foolproof...

Note: Should only be used to deal with data upon submission. It's not something that should be used for general runtime processing.

Parameters:

TXssCleanInput $str <p>input data e.g. string or array of strings</p>

Return:

string|string[]

Support

For support and donations please visit Github | Issues | PayPal | Patreon.

For status updates and release announcements please visit Releases | Twitter | Patreon.

For professional support please contact me.

Thanks

Thanks to GitHub (Microsoft) for hosting the code and a good infrastructure including Issues-Managment, etc.
Thanks to IntelliJ as they make the best IDEs for PHP and they gave me an open source license for PhpStorm!
Thanks to Travis CI for being the most awesome, easiest continous integration tool out there!
Thanks to StyleCI for the simple but powerfull code style check.
Thanks to PHPStan && Psalm for relly great Static analysis tools and for discover bugs in the code!

Name		Name	Last commit message	Last commit date
Latest commit History 568 Commits
.github		.github
build		build
src/voku/helper		src/voku/helper
tests		tests
.editorconfig		.editorconfig
.gitattributes		.gitattributes
.gitignore		.gitignore
.scrutinizer.yml		.scrutinizer.yml
.styleci.yml		.styleci.yml
.travis.yml		.travis.yml
.whitesource		.whitesource
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
circle.yml		circle.yml
composer.json		composer.json
phpcs.php_cs		phpcs.php_cs
phpstan.neon		phpstan.neon
phpunit.xml		phpunit.xml
renovate.json		renovate.json

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㊙️ AntiXSS

DEMO:

NOTES:

Install via "composer require"

Usage:

Unit Test:

AntiXss methods

addDoNotCloseHtmlTags(string[] $strings): $this

addEvilAttributes(string[] $strings): $this

addEvilHtmlTags(string[] $strings): $this

addNeverAllowedCallStrings(string[] $strings): $this

addNeverAllowedJsCallbackRegex(string[] $strings): $this

addNeverAllowedOnEventsAfterwards(string[] $strings): $this

addNeverAllowedRegex(string[] $strings): $this

addNeverAllowedStrAfterwards(string[] $strings): $this

isXssFound(): bool|null

removeDoNotCloseHtmlTags(string[] $strings): $this

removeEvilAttributes(string[] $strings): $this

removeEvilHtmlTags(string[] $strings): $this

removeNeverAllowedCallStrings(string[] $strings): $this

removeNeverAllowedJsCallbackRegex(string[] $strings): $this

removeNeverAllowedOnEventsAfterwards(string[] $strings): $this

removeNeverAllowedRegex(string[] $strings): $this

removeNeverAllowedStrAfterwards(string[] $strings): $this

setReplacement(string $string): $this

setStripe4byteChars(bool $bool): $this

xss_clean(string|string[] $str): string|string[]

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ivanhoe011/anti-xss

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Repository files navigation

㊙️ AntiXSS

DEMO:

NOTES:

Install via "composer require"

Usage:

Unit Test:

AntiXss methods

addDoNotCloseHtmlTags(string[] $strings): $this

addEvilAttributes(string[] $strings): $this

addEvilHtmlTags(string[] $strings): $this

addNeverAllowedCallStrings(string[] $strings): $this

addNeverAllowedJsCallbackRegex(string[] $strings): $this

addNeverAllowedOnEventsAfterwards(string[] $strings): $this

addNeverAllowedRegex(string[] $strings): $this

addNeverAllowedStrAfterwards(string[] $strings): $this

isXssFound(): bool|null

removeDoNotCloseHtmlTags(string[] $strings): $this

removeEvilAttributes(string[] $strings): $this

removeEvilHtmlTags(string[] $strings): $this

removeNeverAllowedCallStrings(string[] $strings): $this

removeNeverAllowedJsCallbackRegex(string[] $strings): $this

removeNeverAllowedOnEventsAfterwards(string[] $strings): $this

removeNeverAllowedRegex(string[] $strings): $this

removeNeverAllowedStrAfterwards(string[] $strings): $this

setReplacement(string $string): $this

setStripe4byteChars(bool $bool): $this

xss_clean(string|string[] $str): string|string[]

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