Difference between revisions of "Category:OWASP AntiSamy Project"

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== Modelo de Auditoría de sistemas:  ==
+
== What is it? ==
  
Éste es un modelo universal para securizar en un alto grado de seguridad al sistema operativo.  
+
The OWASP AntiSamy project is a few things. Technically, it is an API for ensuring user-supplied HTML/CSS is in compliance within an application's rules. Another way of saying that could be: It's an API that helps you make sure that clients don't supply malicious cargo code in the HTML they supply for their profile, comments, etc., that get persisted on the server. The term "malicious code" in regards to web applications usually mean "JavaScript." Cascading Stylesheets are only considered malicious when they invoke the JavaScript engine. However, there are many situations where "normal" HTML and CSS can be used in a malicious manner. So we take care of that too.
  
#Sistema de cifrado congelado: Mantiene en secreto la ubicación del archivo del sistema, previniendo ataques de tipo monitoreo de redes.  
+
Philosophically, AntiSamy is a departure from contemporary security mechanisms. Generally, the security mechanism and user have a communication that is virtually one way, for good reason. Letting the potential attacker know details about the validation is considered unwise as it allows the attacker to "learn" and "recon" the mechanism for weaknesses. These types of information leaks can also hurt in ways you don't expect. A login mechanism that tells the user, "Username invalid" leaks the fact that a user by that name does not exist. A user could use a dictionary or phone book or both to remotely come up with a list of valid usernames. Using this information, an attacker could launch a brute force attack or massive account lock denial-of-service. We get that.
#OpenVAS: Línea de comandos para cifrar- descifrar el protocolo TCP/Ip
+
#Filtro Web: Previene intrusiones a través de puertos inseguros
+
#Clam Antivirus: Previene, detecta y corrige virus informático
+
  
<br>
+
Unfortunately, that's just not very usable in this situation. Typical Internet users are largely pretty bad when it comes to writing HTML/CSS, so where do they get their HTML from? Usually they copy it from somewhere out on the web. Simply rejecting their input without any clue as to why is jolting and annoying. Annoyed users go somewhere else to do their social networking.
  
{| border="1" cellspacing="1" cellpadding="1" width="200" align="center"
+
The [[OWASP_Licenses|OWASP licensing policy]] (further explained in the [[Membership|membership FAQ]]) allows OWASP projects to be released under any [http://www.opensource.org/licenses/alphabetical approved open source license]. Under these guidelines, AntiSamy is distributed under a [http://www.opensource.org/licenses/bsd-license.php BSD license].
|-
+
| Clam Antivirus
+
{| border="1" cellspacing="1" cellpadding="1" width="200" align="center"
+
|-
+
| Filtro Web
+
{| border="1" cellspacing="1" cellpadding="1" width="200" align="center"
+
|-
+
| OpenVAS
+
{| border="1" cellspacing="1" cellpadding="1" width="200" align="center"
+
|-
+
| Sistema de Cifrado Congelado
+
|}
+
  
|}
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== Who are you? ==
  
|}
+
AntiSamy was originally authored by Arshan Dabirsiaghi (arshan.dabirsiaghi [at the] gmail.com) with help from Jason Li (li.jason.c [at the] gmail.com), both of Aspect Security (http://www.aspectsecurity.com/). The problem AntiSamy solves was often described as "impossible" or "impossible to do right". The folks with the AntiSamy project hope to antiquate that idea in a hurry. As of now, there are Java and .NET implementations of AntiSamy, though the framework is implementable in any language. The Java version is callable from ColdFusion.
  
|}
+
PHP developers should use [http://htmlpurifier.org/ HTMLPurifier], another free utility similar to AntiSamy.
  
== Descripción softwares de auditoría  ==
+
== What's the difference between AntiSamy Java, .NET, etc.? ==
  
*El sistema de cifrado http://truecrypt.org cifra el núcleo del sistema operativo y los discos lógicos impidiendo ataques espía.
+
[[AntiSamy Version Differences|This page]] shows a big-picture comparison between the versions. Since it's an unfunded open source project, the ports can't be expected to mirror functionality exactly. If there's something a port is missing -- let us know, and we'll try to accommodate, or write a patch! 
  
*Los comandos shell http://openvas.org sirven para analizar protocolos de red, detección de virus y cifrado del protocolo IpV4-6
+
== How do I get started? ==
  
*El filtro web http://freenetproject.org es una técnica que reemplaza al Firewall, discriminando puertos inseguros, ahorrando tiempo de procesamiento en el núcleo del sistema.
+
There's 4 steps in the process of integrating AntiSamy. Each step is detailed in the next section, but the high level overview follows:
 +
# Download AntiSamy from [http://code.google.com/p/owaspantisamy/downloads/list its home on Google Code]
 +
# Choose one of the standard policy files that matches as close to the functionality you need:
 +
#* antisamy-slashdot.xml
 +
#* antisamy-ebay.xml
 +
#* antisamy-myspace.xml
 +
#* antisamy-anythinggoes.xml
 +
# Tailor the policy file according to your site's rules
 +
# Call the API from the code
  
*Clamwin.com es un software de código abierto, no usa computación en la nube y tiene una GUI que detecta virus en línea http://sourceforge.net/projects/clamsentinel
+
=== Stage 1 - Downloading AntiSamy ===
  
== Macroinformática  ==
+
The following instructions are for AntiSamy Java, the main version. For instructions on the .NET version, see the .NET page.
  
La macroinformática comprende eficiencia, seguridad y naturaleza. La eficacia de un sistema operativo se mide por la interacción hombre-máquina, sintetizando aplicaciones minimalistas y ejecutándolas nuestro sistema operativo procesará los datos eficientemente, ejemplos:
+
Which package you download depends on what you want to do with AntiSamy. If you'd like to extend it or review the code, download the source package. If you're looking to integrate AntiSamy, you can either download the library or use Maven to include it in your build. If you want to use Maven, here's an example POM for including AntiSamy. If you want a jar file, then '''download the antisamy-bin-X.X.X.jar''' (which, before version 1.2 was confusingly called "antisamy-standalone-X.X.X.jar"), which only contains AntiSamy library. This will be the preferred choice for mature enterprise environments who don't want to be caught in classpath issues which may be introduced by the current version.
  
*Transmisión cifrada: Cliente e-mail con GnuPG
+
The second option versions before 1.2 is '''downloading antisamy-standalone-X.X.X.jar''', which contains not only the AntiSamy code, but all necessary supporting libraries. This should only be used by applications that don't use the libraries AntiSamy ships with as they might introduce classpath and versioning issues.
  
http://fellowship.fsfe.org
+
For convenience, the download page also contains the necessary libraries for running AntiSamy in '''antisamy-required-libs.zip'''.
  
*Sistema de cifrado: Cifra y descifra texto plano, imágenes, etc..
+
You can Download AntiSamy from [http://code.google.com/p/owaspantisamy/downloads/list its home on Google Code]
  
#ftp://ftp.gnupg.org/gcrypt/binary/gnupg-w32cli-1.4.11.exe
+
=== Stage 2 - Choosing a base policy file ===
#http://cryptophane.googlecode.com/files/cryptophane-0.7.0.exe
+
  
*Ruby: Lenguaje de programación experimental
+
Chances are that your site's use case for AntiSamy is at least roughly comparable to one of the predefined policy files. They each represent a "typical" scenario for allowing users to provide HTML (and possibly CSS) formatting information. Let's look into the different policy files:
  
http://ruby-lang.org
+
1) antisamy-slashdot.xml
  
*J2re1.3.1_20: Ejecutable de objetos interactivos o applets
+
Slashdot (http://www.slashdot.org/) is a techie news site that allows users to respond anonymously to news posts with very limited HTML markup. Now Slashdot is not only one of the coolest sites around, it's also one that's been subject to many different successful attacks. Even more unfortunate is the fact that most of the attacks led users to the infamous goatse.cx picture (please don't go look it up). The rules for Slashdot are fairly strict: users can only submit the following HTML tags and no CSS: &lt;b&gt;, &lt;u&gt;, &lt;i&gt;, &lt;a&gt;, &lt;blockquote&gt;.
  
http://java.sun.com/products/archive/j2se/1.3.1_20/index.html
+
Accordingly, we've built a policy file that allows fairly similar functionality. All text-formatting tags that operate directly on the font, color or emphasis have been allowed.  
  
*Escritorio: Gestor de ventanas X11
 
  
http://windowmaker.info
 
  
*Gnuzilla: Navegador seguro y de uso libre
+
2) antisamy-ebay.xml
  
http://code.google.com/p/iceweaselwindows/downloads/list
+
eBay (http://www.ebay.com/) is the most popular online auction site in the universe, as far as I can tell. It is a public site so anyone is allowed to post listings with rich HTML content. It's not surprising that given the attractiveness of eBay as a target that it has been subject to a few complex XSS attacks. Listings are allowed to contain much more rich content than, say, Slashdot- so it's attack surface is considerably larger. The following tags appear to be accepted by eBay (they don't publish rules): <a>,...
  
*Gnupdf: Visor de formato de texto universal pdf
 
  
http://blog.kowalczyk.info/software/sumatrapdf
 
  
*Gnuflash: Jugador alternativo a flash player
+
3) antisamy-myspace.xml
  
http://gnu.org/software/gnash
+
MySpace (http://www.myspace.com/) is arguably the most popular social networking site today. Users are allowed to submit pretty much all HTML and CSS they want - as long as it doesn't contain JavaScript. MySpace is currently using a word blacklist to validate users' HTML, which is why they were subject to the infamous Samy worm (http://namb.la/). The Samy worm, which used fragmentation attacks combined with a word that should have been blacklisted (eval) - was the inspiration for the project.
  
*Zinf: Reproductor de audio
 
  
http://zinf.org
+
4) antisamy-anythinggoes.xml
  
*Informática forense: Análisis de datos ocultos en el disco duro
+
I don't know of a possible use case for this policy file. If you wanted to allow every single valid HTML and CSS element (but without JavaScript or blatant CSS-related phishing attacks), you can use this policy file. Not even MySpace is _this_ crazy. However, it does serve as a good reference because it contains base rules for every element, so you can use it as a knowledge base when using tailoring the other policy files.
  
http://sleuthkit.org
 
  
*Compresor: Comprime datos sobreescribiendo bytes repetidos
 
  
http://peazip.sourceforge.net
+
=== Stage 3 - Tailoring the policy file ===
  
*Ftp: Gestor de descarga de archivos
+
Smaller organizations may want to deploy AntiSamy in a default configuration, but it's equally likely that a site may want to have strict, business-driven rules for what users can allow. The discussion that decides the tailoring should also consider attack surface - which grows in relative proportion to the policy file.
  
http://dfast.sourceforge.net
+
You may also want to enable/modify some "directives", which are basically advanced user options. [[AntiSamy Directives|This page]] tells you what the directives are and which versions support them.
  
*AntiKeylogger: Neutraliza el seguimiento de escritorios remotos (Monitoring)
+
=== Stage 4 - Calling the AntiSamy API ===
  
http://psmantikeyloger.sourceforge.net
+
Using AntiSamy is abnormally easy. Here is an example of invoking AntiSamy with a policy file:
  
*Password manager: Gestión de contraseñas
+
<code><pre>import org.owasp.validator.html.*;
  
http://passwordsafe.sourceforge.net
+
Policy policy = Policy.getInstance(POLICY_FILE_LOCATION);
  
*Limpiador de disco: Borra archivos innecesrios del sistema
+
AntiSamy as = new AntiSamy();
 +
CleanResults cr = as.scan(dirtyInput, policy);
  
http://bleachbit.sourceforge.net
+
MyUserDAO.storeUserProfile(cr.getCleanHTML()); // some custom function
 +
</pre></code>
  
*Desfragmentador: Reordena los archivos del disco duro, generando espacio virtual
+
There are a few ways to create a Policy object. The <code>getInstance()</code> method can take any of the following:
 +
* a String filename
 +
* a File object
 +
* an InputStream
  
http://kessels.com/jkdefrag
+
Policy files can also be referenced by filename by passing a second argument to the <code>AntiSamy:scan()</code> method as the following examples show.:
  
*X11: Gestor de ventanas, reemplazo de escritorio Xwindow's
+
<code><pre>AntiSamy as = new AntiSamy();
 +
CleanResults cr = as.scan(dirtyInput, policyFilePath);</pre></code>
  
http://bb4win.org
+
Finally, policy files can also be referenced by File objects directly in the second parameter:
  
*Open Hardware: Hardware construído por la comunidad Linux
+
<code><pre>AntiSamy as = new AntiSamy();
 +
CleanResults cr = as.scan(dirtyInput, new File(policyFilePath));</pre></code>
  
http://open-pc.com
+
=== Stage 5 - Analyzing CleanResults ===
  
*Open WRT: Firmware libre para configurar transmisión de Internet
+
The CleanResults object provides a lot of useful stuff.
  
http://openwrt.org
+
<code>getErrorMessages()</code> - a list of <code>String</code> error messages
  
*Gnu- Linux: Sistema operativo universal
+
<code>getCleanHTML()</code> - the clean, safe HTML output
  
http://gnewsense.org
+
<code>getCleanXMLDocumentFragment()</code> - the clean, safe <code>XMLDocumentFragment</code> which is reflected in <code>getCleanHTML()</code>
  
== Biocriptoseguridad ==: Es la unión de la biología, criptografía y hacking ético para formar una defensa stándar contra virus complejos.
+
<code>getScanTime()</code> - returns the scan time in seconds
  
Implementación de la biocriptoseguridad informática:
+
== Project roadmap ==
  
#Amplificar la banda ancha
+
This section details the status of the various ports of AntiSamy.
#Optimizar (limpiar- modificar) el sistema operativo
+
#Desfragmentar los discos lógicos
+
#Ocultar el sistema operativo
+
#Configurar antivirus
+
#Limpiar y desfragmentar
+
#Congelar
+
  
*Sistema inmune._ Defensa biológica natural contra infecciones como virus http://immunet.com
+
=== Grails ===
 +
Daniel Bower created a [http://www.grails.org/plugin/sanitizer Grails plugin] for AntiSamy.
  
*Criptografía._ Método de escritura oculta por caractes, números y letras:—{H}/gJa¢K¡Ng÷752%\*)A>¡#(W|a— http://diskcryptor.net
+
=== .NET ===
 +
A .NET port of AntiSamy is available now at the [[:Category:OWASP AntiSamy Project .NET|OWASP AntiSamy .NET]] page. The project was funded by a Summer of Code 2008 grant and was developed by Jerry Hoff.  
  
*Hacking ético._ Auditoría de sistemas informáticos que preserva la integridad de los datos.
+
This port is no longer under active development, and is looking for a few good developers to help make it feature-synchronized with the .NET version. If it doesn't suit your needs, consider Microsoft's [http://blogs.msdn.com/b/securitytools/archive/2009/09/01/html-sanitization-in-anti-xss-library.aspx AntiXSS] library.
  
Congelador: Mantiene el equilibrio en la integridad de los datos, el sistema operativo, red , memoria ram, ciclos de CPU, espacio en disco duro e incidencias de malware
+
=== Python ===
 +
A beta Python version is currently being prototyped by a few different groups. As more information becomes available, we will post it here. If you are interested in helping, please contact the mailing list.
  
*http://code.google.com/p/hzr312001/downloads/detail?name=Deep%20systemze%20Standard%20Version%206.51.020.2725.rar&amp;can=2&amp;q= (para Window's)
+
=== PHP ===
*http://sourceforge.net/projects/lethe (para GNU/Linux)
+
Although a PHP version was initially planned, we now suggest [http://htmlpurifier.org HTMLPurifier] for safe rich input validation for PHP applications.
  
<br>Auditoría de virus cifrado._ Un criptovirus se oculta tras un algoritmo de criptografía, generalmente es híbrido simétrico-asimétrico con una extensión de 1700bit's, burla los escáneres antivirus con la aleatoriedad de cifrado, facilitando la expansión de las botnet's. La solución es crear un sistema operativo transparente, anonimizarlo y usar herramientas de cifrado stándar de uso libre:
+
== Presentations on AntiSamy ==
  
*Gnupg: Sirve para cifrar mensajes de correo electrónico http://gpg4win.org/download.html
+
From OWASP & WASC AppSec U.S. 2007 Conference (San Jose, CA): [http://www.owasp.org/images/e/e9/OWASP-WASCAppSec2007SanJose_AntiSamy.ppt AntiSamy - Picking a Fight with XSS (ppt)] - by Arshan Dabirsiaghi - AntiSamy project lead
  
*Open Secure Shell: Ofuscador TcpIp, protege el túnel de comunicación digital cifrando la Ip. http://openvas.org
+
From OWASP AppSec Europe 2008 (Ghent, Belgium): [http://www.owasp.org/images/4/47/AppSecEU08-AntiSamy.ppt The OWASP AntiSamy project (ppt)] - by Jason Li - AntiSamy project contributor
  
*Red protegida: DNS libre http://namespace.org/switch
+
From OWASP AppSec India 2008 (Delhi, India): [https://www.owasp.org/images/9/9d/AppSecIN08-ValidatingRichUserContent.ppt Validating Rich User Content (ppt)] - by Jason Li - AntiSamy project contributor
  
*Criptosistema simétrico: Encapsula el disco duro, incluyendo el sistema operativo,usando algoritmo Twofish http://truecrypt.org/downloads.php
+
From Shmoocon 2009 (Washington, DC): [http://www.shmoocon.org/2009/slides/OWASP%20Winter%202009%20Shmoocon%20-%20Anti%20Samy.pptx AntiSamy - Picking a Fight with XSS (pptx)] - by Arshan Dabirsiaghi - AntiSamy project lead
  
*Proxy cifrado: Autenticación de usuario anónimo http://torproject.org
+
== Contacting us ==
 +
There are two ways of getting information on AntiSamy. The mailing list, and contacting the project lead directly.
  
Energías renovables._ Son energías adquiridas por medios naturales: hidrógeno, aire, sol que disminuyen la toxicidad de las emisiones de Co2 en el medio ambiente, impulsando políticas ecologistas contribuímos a preservar el ecosistema. Ejm: Usando paneles solares fotovoltaicos.
+
=== OWASP AntiSamy mailing list ===
 +
The first is the mailing list which is located at https://lists.owasp.org/mailman/listinfo/owasp-antisamy. The list was previously private and the archives have been cleared with the release of version 1.0. We encourage all prospective and current users and bored attackers to join in the conversation. We're happy to brainstorm attack scenarios, discuss regular expressions and help with integration.
 +
 
 +
=== Emailing the project lead ===
 +
 
 +
For content which is not appropriate for the public mailing list, you can alternatively contact the project lead, Arshan Dabirsiaghi, at [arshan.dabirsiaghi] at [aspectsecurity.com].
 +
 
 +
=== Issue tracking ===
 +
 
 +
Visit the [http://code.google.com/p/owaspantisamy/issues/list Google Code issue tracker].
 +
 
 +
== Sponsors ==
 +
 
 +
The initial Java project was sponsored by the [[OWASP Spring Of Code 2007|OWASP Spring Of Code 2007]]. The .NET project was sponsored by the [[OWASP Summer of Code 2008]]
 +
 
 +
== Project's Assessment ==
 +
 
 +
This project was assessed by [[:User:Jeff Williams|Jeff Williams]] and his evaluation can be seen [http://spreadsheets.google.com/ccc?key=pAX6n7m2zaTW-JtGBqixbTw '''here'''].
 +
 
 +
[[Category:OWASP Project|AntiSamy Project]]
 +
[[Category:OWASP Tool]]
 +
[[Category:OWASP Download]]
 +
[[Category:OWASP Release Quality Tool]]

Revision as of 18:07, 7 February 2011

Contents

What is it?

The OWASP AntiSamy project is a few things. Technically, it is an API for ensuring user-supplied HTML/CSS is in compliance within an application's rules. Another way of saying that could be: It's an API that helps you make sure that clients don't supply malicious cargo code in the HTML they supply for their profile, comments, etc., that get persisted on the server. The term "malicious code" in regards to web applications usually mean "JavaScript." Cascading Stylesheets are only considered malicious when they invoke the JavaScript engine. However, there are many situations where "normal" HTML and CSS can be used in a malicious manner. So we take care of that too.

Philosophically, AntiSamy is a departure from contemporary security mechanisms. Generally, the security mechanism and user have a communication that is virtually one way, for good reason. Letting the potential attacker know details about the validation is considered unwise as it allows the attacker to "learn" and "recon" the mechanism for weaknesses. These types of information leaks can also hurt in ways you don't expect. A login mechanism that tells the user, "Username invalid" leaks the fact that a user by that name does not exist. A user could use a dictionary or phone book or both to remotely come up with a list of valid usernames. Using this information, an attacker could launch a brute force attack or massive account lock denial-of-service. We get that.

Unfortunately, that's just not very usable in this situation. Typical Internet users are largely pretty bad when it comes to writing HTML/CSS, so where do they get their HTML from? Usually they copy it from somewhere out on the web. Simply rejecting their input without any clue as to why is jolting and annoying. Annoyed users go somewhere else to do their social networking.

The OWASP licensing policy (further explained in the membership FAQ) allows OWASP projects to be released under any approved open source license. Under these guidelines, AntiSamy is distributed under a BSD license.

Who are you?

AntiSamy was originally authored by Arshan Dabirsiaghi (arshan.dabirsiaghi [at the] gmail.com) with help from Jason Li (li.jason.c [at the] gmail.com), both of Aspect Security (http://www.aspectsecurity.com/). The problem AntiSamy solves was often described as "impossible" or "impossible to do right". The folks with the AntiSamy project hope to antiquate that idea in a hurry. As of now, there are Java and .NET implementations of AntiSamy, though the framework is implementable in any language. The Java version is callable from ColdFusion.

PHP developers should use HTMLPurifier, another free utility similar to AntiSamy.

What's the difference between AntiSamy Java, .NET, etc.?

This page shows a big-picture comparison between the versions. Since it's an unfunded open source project, the ports can't be expected to mirror functionality exactly. If there's something a port is missing -- let us know, and we'll try to accommodate, or write a patch!

How do I get started?

There's 4 steps in the process of integrating AntiSamy. Each step is detailed in the next section, but the high level overview follows:

  1. Download AntiSamy from its home on Google Code
  2. Choose one of the standard policy files that matches as close to the functionality you need:
    • antisamy-slashdot.xml
    • antisamy-ebay.xml
    • antisamy-myspace.xml
    • antisamy-anythinggoes.xml
  3. Tailor the policy file according to your site's rules
  4. Call the API from the code

Stage 1 - Downloading AntiSamy

The following instructions are for AntiSamy Java, the main version. For instructions on the .NET version, see the .NET page.

Which package you download depends on what you want to do with AntiSamy. If you'd like to extend it or review the code, download the source package. If you're looking to integrate AntiSamy, you can either download the library or use Maven to include it in your build. If you want to use Maven, here's an example POM for including AntiSamy. If you want a jar file, then download the antisamy-bin-X.X.X.jar (which, before version 1.2 was confusingly called "antisamy-standalone-X.X.X.jar"), which only contains AntiSamy library. This will be the preferred choice for mature enterprise environments who don't want to be caught in classpath issues which may be introduced by the current version.

The second option versions before 1.2 is downloading antisamy-standalone-X.X.X.jar, which contains not only the AntiSamy code, but all necessary supporting libraries. This should only be used by applications that don't use the libraries AntiSamy ships with as they might introduce classpath and versioning issues.

For convenience, the download page also contains the necessary libraries for running AntiSamy in antisamy-required-libs.zip.

You can Download AntiSamy from its home on Google Code

Stage 2 - Choosing a base policy file

Chances are that your site's use case for AntiSamy is at least roughly comparable to one of the predefined policy files. They each represent a "typical" scenario for allowing users to provide HTML (and possibly CSS) formatting information. Let's look into the different policy files:

1) antisamy-slashdot.xml

Slashdot (http://www.slashdot.org/) is a techie news site that allows users to respond anonymously to news posts with very limited HTML markup. Now Slashdot is not only one of the coolest sites around, it's also one that's been subject to many different successful attacks. Even more unfortunate is the fact that most of the attacks led users to the infamous goatse.cx picture (please don't go look it up). The rules for Slashdot are fairly strict: users can only submit the following HTML tags and no CSS: <b>, <u>, <i>, <a>, <blockquote>.

Accordingly, we've built a policy file that allows fairly similar functionality. All text-formatting tags that operate directly on the font, color or emphasis have been allowed.


2) antisamy-ebay.xml

eBay (http://www.ebay.com/) is the most popular online auction site in the universe, as far as I can tell. It is a public site so anyone is allowed to post listings with rich HTML content. It's not surprising that given the attractiveness of eBay as a target that it has been subject to a few complex XSS attacks. Listings are allowed to contain much more rich content than, say, Slashdot- so it's attack surface is considerably larger. The following tags appear to be accepted by eBay (they don't publish rules): <a>,...


3) antisamy-myspace.xml

MySpace (http://www.myspace.com/) is arguably the most popular social networking site today. Users are allowed to submit pretty much all HTML and CSS they want - as long as it doesn't contain JavaScript. MySpace is currently using a word blacklist to validate users' HTML, which is why they were subject to the infamous Samy worm (http://namb.la/). The Samy worm, which used fragmentation attacks combined with a word that should have been blacklisted (eval) - was the inspiration for the project.


4) antisamy-anythinggoes.xml

I don't know of a possible use case for this policy file. If you wanted to allow every single valid HTML and CSS element (but without JavaScript or blatant CSS-related phishing attacks), you can use this policy file. Not even MySpace is _this_ crazy. However, it does serve as a good reference because it contains base rules for every element, so you can use it as a knowledge base when using tailoring the other policy files.


Stage 3 - Tailoring the policy file

Smaller organizations may want to deploy AntiSamy in a default configuration, but it's equally likely that a site may want to have strict, business-driven rules for what users can allow. The discussion that decides the tailoring should also consider attack surface - which grows in relative proportion to the policy file.

You may also want to enable/modify some "directives", which are basically advanced user options. This page tells you what the directives are and which versions support them.

Stage 4 - Calling the AntiSamy API

Using AntiSamy is abnormally easy. Here is an example of invoking AntiSamy with a policy file:

import org.owasp.validator.html.*;

Policy policy = Policy.getInstance(POLICY_FILE_LOCATION);

AntiSamy as = new AntiSamy();
CleanResults cr = as.scan(dirtyInput, policy);

MyUserDAO.storeUserProfile(cr.getCleanHTML()); // some custom function

There are a few ways to create a Policy object. The getInstance() method can take any of the following:

  • a String filename
  • a File object
  • an InputStream

Policy files can also be referenced by filename by passing a second argument to the AntiSamy:scan() method as the following examples show.:

AntiSamy as = new AntiSamy();
CleanResults cr = as.scan(dirtyInput, policyFilePath);

Finally, policy files can also be referenced by File objects directly in the second parameter:

AntiSamy as = new AntiSamy();
CleanResults cr = as.scan(dirtyInput, new File(policyFilePath));

Stage 5 - Analyzing CleanResults

The CleanResults object provides a lot of useful stuff.

getErrorMessages() - a list of String error messages

getCleanHTML() - the clean, safe HTML output

getCleanXMLDocumentFragment() - the clean, safe XMLDocumentFragment which is reflected in getCleanHTML()

getScanTime() - returns the scan time in seconds

Project roadmap

This section details the status of the various ports of AntiSamy.

Grails

Daniel Bower created a Grails plugin for AntiSamy.

.NET

A .NET port of AntiSamy is available now at the OWASP AntiSamy .NET page. The project was funded by a Summer of Code 2008 grant and was developed by Jerry Hoff.

This port is no longer under active development, and is looking for a few good developers to help make it feature-synchronized with the .NET version. If it doesn't suit your needs, consider Microsoft's AntiXSS library.

Python

A beta Python version is currently being prototyped by a few different groups. As more information becomes available, we will post it here. If you are interested in helping, please contact the mailing list.

PHP

Although a PHP version was initially planned, we now suggest HTMLPurifier for safe rich input validation for PHP applications.

Presentations on AntiSamy

From OWASP & WASC AppSec U.S. 2007 Conference (San Jose, CA): AntiSamy - Picking a Fight with XSS (ppt) - by Arshan Dabirsiaghi - AntiSamy project lead

From OWASP AppSec Europe 2008 (Ghent, Belgium): The OWASP AntiSamy project (ppt) - by Jason Li - AntiSamy project contributor

From OWASP AppSec India 2008 (Delhi, India): Validating Rich User Content (ppt) - by Jason Li - AntiSamy project contributor

From Shmoocon 2009 (Washington, DC): AntiSamy - Picking a Fight with XSS (pptx) - by Arshan Dabirsiaghi - AntiSamy project lead

Contacting us

There are two ways of getting information on AntiSamy. The mailing list, and contacting the project lead directly.

OWASP AntiSamy mailing list

The first is the mailing list which is located at https://lists.owasp.org/mailman/listinfo/owasp-antisamy. The list was previously private and the archives have been cleared with the release of version 1.0. We encourage all prospective and current users and bored attackers to join in the conversation. We're happy to brainstorm attack scenarios, discuss regular expressions and help with integration.

Emailing the project lead

For content which is not appropriate for the public mailing list, you can alternatively contact the project lead, Arshan Dabirsiaghi, at [arshan.dabirsiaghi] at [aspectsecurity.com].

Issue tracking

Visit the Google Code issue tracker.

Sponsors

The initial Java project was sponsored by the OWASP Spring Of Code 2007. The .NET project was sponsored by the OWASP Summer of Code 2008

Project's Assessment

This project was assessed by Jeff Williams and his evaluation can be seen here.

Subcategories

This category has the following 2 subcategories, out of 2 total.