Wiki source code of Security

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version	line-number	content
38.1	1
34.1	2	This page aims at listing the various security aspects an administrator needs to be aware of when dealing with XWiki. For all security decision a developer needs to take when writing scripts and extensions, you should have a look to [[the security page of the developer guide>>Documentation.DevGuide.Security.WebHome]].
	3
9.1	4	{{box cssClass="floatinginfobox" title="Contents"}}
	5	{{toc/}}
	6	{{/box}}
5.1	7
26.1	8	= Security Policy =
	9
	10	XWiki security policy [[is detailed here>>dev:Community.SecurityPolicy.WebHome]].
	11
6.1	12	= Security related features =
9.1	13
6.1	14	XWiki offers some features for protecting security and some features which have security implications.
1.2	15
6.1	16	== Admin password ==
9.1	17
37.5	18	If you've [[installed a Standalone (Demo) Distribution>>documentation.xs.admin.installation.methods.install-standalone-demo-distribution.WebHome]], then a default administration user is pre-created for you:
29.2	19
26.2	20	* Username: ##Admin##
	21	* Password: ##admin##
2.1	22
26.2	23	Note: You could also remove that user but first you need to make sure it's not used as author of any page as it might create issue otherwise (some standard pages require their author to have enough right to be taken into account).
13.1	24
26.2	25	If you've used any other packaging to install XWiki, the [[Distribution Wizard>>Documentation.UserGuide.Features.DistributionWizard]] asks you to create an administration account and you get to choose the username and password.
	26
6.1	27	== Superadmin account ==
9.1	28
13.2	29	XWiki provides a ##superadmin## account. It is special, because:
13.1	30
1.3	31	* It is not stored in the database
	32	* It cannot be modified in any way
	33	* It always has full access, regardless of the rights settings
	34
5.1	35	{{warning}}
12.5	36	Because the Superadmin account is so powerful, it is not safe to leave it enabled for a long time.
5.1	37	{{/warning}}
1.5	38
12.5	39	By default, this account is disabled. To enable it, you have to edit ##<xwiki-dir>/WEB-INF/xwiki.cfg##, uncomment the ##xwiki.superadminpassword=system## line and set a proper password. To disable it, just comment this line. Remember to restart the servlet container after changing ##xwiki.cfg##.
1.3	40
5.1	41	{{info}}
	42	Using this superadmin account is useful when you cannot log in anymore, for example when you forgot your admin user password, if you messed up some rights or if you have deleted your admin user by mistake.
	43	{{/info}}
1.4	44
6.1	45	== Cookies ==
9.1	46
29.1	47	XWiki uses several cookies on the user's machines. For example, XWiki identifies users who have already logged in by setting cookies. These can be the target of attacks.
1.1	48
29.1	49	=== Cookies List ===
	50
	51	This is the full list of Cookies used by XWiki core (if you install Extensions, they may define their own cookies and you would need to refer to their documentation).
	52
36.1	53	\|= Cookie name\|=Content\|=Path\|=Domain\|=Max age\|=Is Secure?\|=Http Only?\|=Usage
	54	\|##JSESSIONID##\|Unique number representing the Session\|##/##\|Web site domain\|Session duration (30mn by default, can be configured in ##web.xml##)\|Yes if request is using HTTPS (can depend on Servlet Container)\|Yes if request is using HTTPS (can depend on Servlet Container)\|Session cookie created by the Servlet Container
36.5	55	\|##ckCsrfToken##\|Unique number (CSRF Token)\|##/##\|Web site domain\|Session duration (30mn by default, can be configured in ##web.xml##)\|Yes\|Yes\|Created by CKEditor. The CSRF token can be used to secure the communication between the web browser and the server, i.e. for the file upload feature in the editor. However XWiki doesn't use it as it has its own CSRF token mechanism.
36.2	56	\|##language##\|Current user locale\|##/##\|Not set\|10 years\|No\|No\|Remember the locale used
36.3	57	\|##interfacelanguage##\|The interface language used for the current user\|##/##\|Not set\|10 years\|No\|No\|Remember the UI language used
36.4	58	\|##visitid##\|Random alphanumeric value of 32 characters\|##/##\|A value from the comma-separated list from the ##xwiki.authentication.cookiedomains## config parameter, if it matches the server name\|Difference between 1 Jan 2030 and current date\|No\|No\|To uniquely recognize the user when computing visit stats. Note that the stats feature is deprecated and turned off.
36.1	59	\|##[xwiki.authentication.cookieprefix]username##\|The protected user name (i.e. encrypted using ##[xwiki.authentication.encryptionKey]## if ##xwiki.authentication.protection## is set)\|##[xwiki.authentication.cookiepath]## or ##/## if not set\|##[xwiki.authentication.cookiedomains]## matching the server name of ##/## if not set or no match\|##[xwiki.authentication.cookielife]## (in days) or 15 days if not set, or until browser shutdown if "remember me" is not checked\|Yes if request is using HTTPS\|Yes\|Remember me (if external authentication is used, this cookie may not be used). If ##xwiki.authentication.cookieprefix## is not set, then an empty string is used.
	60	\|##[xwiki.authentication.cookieprefix]password##\|The protected password(i.e. encrypted using ##[xwiki.authentication.encryptionKey]## if ##xwiki.authentication.protection## is set)\|##[xwiki.authentication.cookiepath]## or ##/## if not set\|##[xwiki.authentication.cookiedomains]## matching the server name of ##/## if not set or no match\|##[xwiki.authentication.cookielife]## (in days) or 15 days if not set, or until browser shutdown if "remember me" is not checked\|Yes if request is using HTTPS\|Yes\|Remember me (if external authentication is used, this cookie may not be used). If ##xwiki.authentication.cookieprefix## is not set, then an empty string is used.
	61	\|##[xwiki.authentication.cookieprefix]rememberme##\|True if remember me is checked, false otherwise\|##[xwiki.authentication.cookiepath]## or ##/## if not set\|##[xwiki.authentication.cookiedomains]## matching the server name of ##/## if not set or no match\|##[xwiki.authentication.cookielife]## (in days) or 15 days if not set, or until browser shutdown if "remember me" is not checked\|Yes if request is using HTTPS\|Yes\|Remember me (if external authentication is used, this cookie may not be used). If ##xwiki.authentication.cookieprefix## is not set, then an empty string is used.
	62	\|##[xwiki.authentication.cookieprefix]validation##\|MD5 hash based on the protected username, protected password and the IP addres (if ##xwiki.authentication.useip## is set)\|##[xwiki.authentication.cookiepath]## or ##/## if not set\|##[xwiki.authentication.cookiedomains]## matching the server name of ##/## if not set or no match\|##[xwiki.authentication.cookielife]## (in days) or 15 days if not set, or until browser shutdown if "remember me" is not checked\|Yes if request is using HTTPS\|Yes\|Remember me (if external authentication is used, this cookie may not be used). If ##xwiki.authentication.cookieprefix## is not set, then an empty string is used.
29.1	63
	64	Legend help:
29.2	65
29.1	66	* If "Is Secure?" is true, it means that the cookie is only sent when HTTPS is used.
	67
37.1	68	=== Session Cookie Security ===
	69
	70	In general, Servlet Containers create the ##JSESSIONID## cookie as ##secure## only when the connexion is made on HTTPS (i.e. on an HTTP connexion the cookie is NOT ##secure## and is thus sent client-side). Some Servlet Containers always set ##httpOnly## but some don't.
	71
	72	You can configure your Servlet Container to never send the ##JSESSIONID## cookie, at the level of the Servlet Container's configuration files (e.g. in Tomcat's ##web.xml## file). You could also edit XWiki's ##web.xml## file and use:
	73
	74	{{code language="xml"}}
	75	<session-config>
	76	<cookie-config>
	77	<http-only>true</http-only>
	78	<secure>true</secure>
	79	</cookie-config>
	80	</session-config>
	81	{{/code}}
	82
29.2	83	=== Cookie Encryption Keys ===
9.1	84
37.4	85	When a user logs in, three cookies are saved on his machine containing the username, password and a "nothing up my sleeve" hash. The cookies are encrypted so that nobody having access to them can see the username/password. This encryption is done using 2 configuration parameters located in the //xwiki.cfg// configuration file. This file is located in //WEB-INF/// in the XWiki WAR (see the [[Installation WAR guide>>Documentation.AdminGuide.Installation.InstallationWAR.WebHome]] for where it's installed).
29.2	86
	87	{{version before="15.9, 15.5.4, 14.10.19"}}
21.4	88	It's important you edit the //[[xwiki.cfg>>Documentation.AdminGuide.Configuration#HSamplexwiki.cfg]]// file to modify the cookie authentication and encryption keys as they use default values when you install XWiki and these predefined values could be used by an attacker to decipher the username and password. To prevent this, change the following 2 configuration parameters:
13.1	89
5.1	90	* //xwiki.authentication.validationKey//
	91	* //xwiki.authentication.encryptionKey//
29.2	92	{{/version}}
1.1	93
38.1	94	See the [[Authentication Parameters>>documentation.xs.admin.authentication.parameters.WebHome]] page for more details.
6.1	95
	96	=== Encrypt cookies using IP address ===
9.1	97
23.2	98	Even if the password cannot be extracted from the cookie, the cookies might be stolen (see [[XSS>>Documentation.AdminGuide.Security#HCrossSiteScripting]]) and used as they are. To limit this by default, the cookies are blocked from being used except by the same IP address that was used to create them.
6.1	99
23.2	100	You can disable this by setting the [[##xwiki.cfg##>>Documentation.AdminGuide.Configuration#HSamplexwiki.cfg]] parameter ##xwiki.authentication.useip## to false.
	101
7.1	102	== Override version information ==
	103
20.1	104	By default, the exact XWiki version is shown in the footer of every page. This is not harmful by itself, but can provide useful information to the attacker, who can use known vulnerabilities against this version.
7.1	105
23.3	106	You can change the version string shown in the footer using the [[Administration Application>>extensions:Extension.Administration Application]]. Click on the ##Presentation## icon and change the version string in the //Version// field. Please note that with this solution, the version can still be find through a REST request on the wiki.
7.1	107
12.5	108	If you want to be sure the version is definitely not leaked somewhere else, you can replace the file //WEB-INF/version.properties// by your own version with the following content: {{code}}version=your version string here{{/code}}.
7.1	109
33.1	110	= Antivirus =
	111
	112	There's an [[Antivirus Application>>https://store.xwiki.com/xwiki/bin/view/Extension/AntivirusApplication/]] developed by a sponsoring company offering scanning for antivirus when attaching files to wiki pages.
	113
6.1	114	= Discussion of attack vectors =
9.1	115
6.1	116	Perfect security is generally considered impossible. With simple static HTML servers we can have near perfect security but those are not very useful. This document discusses different threat models and how to fortify against each. These attacks are grouped by type of access gained if successful. More dangerous attacks are near the top yet the most common attacks are less dangerous (and easier to perform) and will be seen at the bottom.
	117
	118	== Server root attacks ==
9.1	119
6.1	120	This attack is characterized by assent of power in the operating system and is largely beyond the scope of this document as it is the responsibility of the operating system to prevent users ascending power.
	121
	122	=== Likelihood / Known Issues ===
9.1	123
6.1	124	Not a very common attack method.
	125
	126	=== Mitigation Methods ===
9.1	127
6.1	128	* Run a decent operating system
12.5	129	* Run the Java VM with XWiki under its own username, only give this user permissions to files needed for the operation of XWiki and make sure this user doesn't have sudo access
6.1	130	* Don't run extraneous processes on the server
	131	* Run services on non-standard ports (ssh)
	132	* Firewall all ports not explicitly needed
	133
	134	== Java VM attacks ==
9.1	135
6.1	136	This attack is characterized by the attacker running arbitrary code on Java and perhaps using Java level security flaws to execute native code thus gaining access in the user level of the Java VM process.
	137
	138	=== Likelihood / Known Issues ===
9.1	139
12.5	140	* XWiki requires reflection of private fields and variables for the [[component module>>extensions:Extension.Component Module]] This means that jsr223 scripts such as Groovy and Python are able to read and write any field or variable in the system which may lead to execution of native code via Java Native Access. Virtual wikis are not insulated against this attack method and as such virtual wiki administrators cannot be given programming permission (note that there is another reason for not giving wiki admin programming rights in a farm, it is because you may access any document without rights being checked, even in another wiki). This flaw could lead to dumping of connected databases, however user passwords are SHA-512 hashed (see [[this issue>>http://jira.codehaus.org/browse/GROOVY-1875]] for more details.
	141	** This attack method requires the use of a registered username which has programming rights
6.1	142
	143	=== Mitigation Methods ===
9.1	144
12.5	145	* Enable a SecurityManager which peeks at the calling stack and only allows unchecked reflection if called by the component manager
	146	* Disable Groovy entirely
	147	* Guard programming rights closely, have a special username just for saving documents which contain approved Groovy scripts
6.1	148
	149	== Database Injection attacks ==
9.1	150
6.1	151	Such an attack happens from inside of unsafe scripting and results in unintended information being given up by the database.
	152
	153	=== Likelihood / Known Issues ===
9.1	154
6.1	155	* XWiki uses Hibernate as a database controller so some of the injection methods are mitigated. XWiki gives you the capability to create safe scripts and unsafe scripts.
	156	** This attack method may often be performed without a registered username.
	157
	158	=== Mitigation Methods ===
9.1	159
13.1	160	* You can use this groovy snippet to test your database to see if it supports [[stacked queries>>http://ferruh.mavituna.com/sql-injection-cheatsheet-oku/#StackingQueries]]. If your database does not support stacked queries, injection in a SELECT query can only lead to additional arbitrary SELECT queries:(((
9.1	161	{{code language="java"}}
6.1	162	{{groovy}}
	163	try {
	164	session = xcontext.getContext().getWiki().getHibernateStore().getSessionFactory().openSession();
	165	session.connection().createStatement().execute("begin transaction; rollback;");
	166	println("Your database supports stacked queries.")
	167	} catch (Exception e) {
	168	println("Your database does not support stacked queries.");
	169	} finally {
	170	try {
	171	session.close()
	172	} catch (Exception e) {}
	173	}
	174	{{/groovy}}
	175	{{/code}}
12.5	176	)))
	177	* Configure your database to log or if possible disable comment syntax {{code language="none"}} -- /* */ and # {{/code}}. Comments are not used by Hibernate and are central to most of the more dangerous SQL injection.
	178	* When designing scripts avoid the temptation to concatenate user input into database queries
6.1	179
	180	WRONG:
	181
	182	{{code}}
	183	#set($x = $xwiki.searchDocuments("where doc.fullName = '${userContent}'"))
	184	{{/code}}
	185
12.5	186	If the user enters: {{code}} ' or doc.hidden = 1 or doc.fullName = ' {{/code}} your code will create the Hibernate query: {{code language="sql"}}where doc.fullName = '' or doc.hidden = 1 or doc.fullName = ''{{/code}}.
6.1	187
	188	This may not be a horrible outcome but it is not what you wanted and others surely can invent far more dangerous injections than this.
	189	Fortunately Hibernate itself protects against the worst type of injection such as:
	190
9.1	191	{{code language="sql"}}
6.1	192	Embarrassing Mistake'); DROP TABLE xwikidoc;--
	193	{{/code}}
	194
12.5	195	This is because it does not allow multiple commands in one call and does not allow the ~-~- comment syntax (can be bypassed in some versions; see above).
6.1	196
12.5	197	RIGHT:
6.1	198
	199	{{code}}
	200	## We are passing a ? in the query and then passing the parameter as a list (Velocity notation for list is [element, element] )
	201	#set($x = $xwiki.searchDocuments("where doc.fullName = ?", [$userContent]))
	202	{{/code}}
	203
	204	Your code will now instruct Hibernate to name the userContent parameter and pass it to the database separately from the query. The above injection trick will not work.
	205
12.5	206	* Avoid "Privileged API" whenever possible and only use non API when absolutely necessary. If each of your calls requires you to pass the context as a parameter, you're doing it wrong.
6.1	207
27.1	208	For more information check the [[XWiki API Reference>>Documentation.DevGuide.API]].
6.1	209
	210	== Cross Site Scripting ==
9.1	211
6.1	212	Cross site scripting or XSS is the least harmful to the server of all attack methods, however it is the most common.
12.5	213	XSS can lead to users altering documents which they didn't want to or having their authentication cookies copied. XSS can also lead to exploitation of web browsers and plugins such as pdf or ActiveX. Such exploits often install malware.
6.1	214
	215	=== Attack vectors (persistent injection) ===
9.1	216
6.1	217	Persistent injection is characterized by saving content in the system which when loaded by the unwitting user, executes as javascript in their browser. This is the more dangerous variety because it sits in a page waiting for a victim.
	218
	219	1. Persistent injection through XWiki document content by editing the document.
	220	2. Persistent injecting through comments.
	221
	222	==== Likelihood / Known Issues ====
9.1	223
6.1	224	* XWiki syntax 1.0 does not filter out HTML so script injection is possible
17.1	225	* XWiki syntax 2.0 contains html macro which when invoked allows injection of raw html and script. There is still no safe way to disable this (see [[this issue>>https://jira.xwiki.org/browse/XWIKI-3953]] for more information.
12.5	226	** This attack method requires the attacker to have a registered username (unless anonymous editing or commenting is allowed).
6.1	227
	228	==== Mitigation Methods ====
9.1	229
13.1	230	* The only way to be sure that script cannot be injected in content (xwiki/1.0 or xwiki/2.0) is to make that content completely passive as follows:(((
6.1	231	{{code}}
	232	{{html}}
	233	$escapetool.html($userContent)
	234	{{/html}}
	235	{{/code}}
13.1	236	)))There are however some methods to minimize the risk:
12.5	237	* Disable creation of syntax 1.0 pages. NOTE: Pages which are already written in syntax 1.0 can still be altered and should be updated to syntax 2.0, otherwise they must have edit permission locked down so that only authorized users may edit them.
	238	* Force unauthorized users to post through a script which escapes //~{~{// (double squigly brackets) because there is currently no way to prevent injection of html macro for unauthorized users.
	239	* Set up ObservationManager to scan all page content and object property updates for HTML macro invocation and alert a moderator.
9.1	240
6.1	241	=== Attack vectors (reflective injection) ===
9.1	242
6.1	243	Reflective injection is characterized by convincing a user to click on a specially crafted link which causes a page to generate javascript.
	244
	245	1. Reflective injection through form fields.
	246
	247	==== Mitigation Methods ====
9.1	248
12.5	249	Advise admins to use addons such as [[noscript>>https://addons.mozilla.org/en-US/firefox/addon/noscript/]] which will detect reflective injection attacks and warn the user when it suspects foul play and also avoid clicking on suspicious links.
6.1	250
12.5	251	* when content is loaded from request parameters into a form field, make sure it is escaped using [[EscapeTool>>http://velocity.apache.org/tools/devel/generic/EscapeTool.html]]
6.1	252
	253	WRONG:
	254
9.1	255	{{code language="xml"}}
6.1	256	<input type=text value="$request.get('name')" />
	257	{{/code}}
	258
	259	RIGHT:
	260
9.1	261	{{code language="xml"}}
6.1	262	<input type=text value="$escapetool.html($request.get('name'))" />
	263	{{/code}}
	264
	265	== Cross site request forgery (CSRF) ==
9.1	266
6.1	267	The basis of this attack is that a foreign website can craft a malicious link or form which points to the save action in your system and when clicked by a logged in user will cause the user to save the page.
	268
	269	=== Likelihood / Known Issues ===
9.1	270
12.5	271	Currently there is no system implemented to prevent form submission from external sites. See discussion in mailing list about implementing [[secret tokens>>http://lists.xwiki.org/pipermail/devs/2010-March/017727.html]].
6.1	272
	273	=== Mitigation Methods ===
9.1	274
12.5	275	Advise admins to use addons such as [[noscript>>https://addons.mozilla.org/en-US/firefox/addon/noscript/]] which will help prevent automatic form submission by an attack site and also avoid clicking on suspicious links.
19.1	276
19.2	277	= Advisory Notices =
19.1	278
	279	Here's a list of sites offering security advisory notices about XWiki:
20.1	280
35.1	281	* [[nvd.nist.gov>>https://nvd.nist.gov/vuln/search/results?form_type=Basic&results_type=overview&query=xwiki&search_type=all&isCpeNameSearch=false]]
19.1	282	* [[www.cvedetails.com>>http://www.cvedetails.com/product/6856/Xwiki-Xwiki.html?vendor_id=3885]]
	283	* [[vuldb.com>>https://vuldb.com/fr/?search]] (need to search for ##xwiki##)
	284	* [[vulners.com>>https://vulners.com/search?query=xwiki]]

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