changelog

[git.ikiwiki.info.git] / doc / security.mdwn

diff --git a/doc/security.mdwn b/doc/security.mdwn
index 830cd415b1de67ad08928dfd55b79630bdb8d9d9..b573b5f2348a3bea028706f1af7d5433b3b0f9a7 100644 (file)
--- a/doc/security.mdwn
+++ b/doc/security.mdwn
@@ -6,7 +6,7 @@ security issues with this program than with cat(1). If, however, you let
 others edit pages in your wiki, then some possible security issues do need
 to be kept in mind.
 
 others edit pages in your wiki, then some possible security issues do need
 to be kept in mind.
 

-[[toc levels=2]]
+[[!toc levels=2]]

 
 ----
 
 
 ----
 


@@ -22,8 +22,8 @@ this would be to limit web commits to those done by a certain user.
 
 ## other stuff to look at
 
 
 ## other stuff to look at
 

-I need to audit the git backend a bit, and have been meaning to
-see if any CRLF injection type things can be done in the CGI code.
+I have been meaning to see if any CRLF injection type things can be
+done in the CGI code.

 
 ----
 
 
 ----
 


@@ -41,11 +41,19 @@ who's viewing the wiki, that can be a security problem.
 
 Of course nobody else seems to worry about this in other wikis, so should we?
 
 
 Of course nobody else seems to worry about this in other wikis, so should we?
 

-Currently only people with direct commit access can upload such files
+People with direct commit access can upload such files

 (and if you wanted to you could block that with a pre-commit hook).
 (and if you wanted to you could block that with a pre-commit hook).

-Users with only web commit access are limited to editing pages as ikiwiki
-doesn't support file uploads from browsers (yet), so they can't exploit
-this.
+
+The attachments plugin is not enabled by default. If you choose to
+enable it, you should make use of its powerful abilities to filter allowed
+types of attachments, and only let trusted users upload.
+
+It is possible to embed an image in a page edited over the web, by using
+`img src="data:image/png;"`. Ikiwiki's htmlscrubber only allows `data:`
+urls to be used for `image/*` mime types. It's possible that some broken
+browser might ignore the mime type and if the data provided is not an
+image, instead run it as javascript, or something evil like that. Hopefully
+not many browsers are that broken.

 
 ## multiple accessors of wiki directory
 
 
 ## multiple accessors of wiki directory
 


@@ -57,16 +65,15 @@ So it's best if only one person can ever directly write to those directories.
 
 ## setup files
 
 
 ## setup files
 

-Setup files are not safe to keep in subversion with the rest of the wiki.
-Just don't do it. [[ikiwiki.setup]] is *not* used as the setup file for
-this wiki, BTW.
+Setup files are not safe to keep in the same revision control repository
+with the rest of the wiki. Just don't do it.

 
 ## page locking can be bypassed via direct commits
 
 A locked page can only be edited on the web by an admin, but anyone who is
 allowed to commit directly to the repository can bypass this. This is by
 design, although a pre-commit hook could be used to prevent editing of
 
 ## page locking can be bypassed via direct commits
 
 A locked page can only be edited on the web by an admin, but anyone who is
 allowed to commit directly to the repository can bypass this. This is by
 design, although a pre-commit hook could be used to prevent editing of

-locked pages when using subversion, if you really need to.
+locked pages, if you really need to.

 
 ## web server attacks
 
 
 ## web server attacks
 


@@ -98,7 +105,7 @@ your web server will not run it.
 
 ## suid wrappers
 
 
 ## suid wrappers
 

-ikiwiki --wrapper is intended to generate a wrapper program that
+`ikiwiki --wrapper` is intended to generate a wrapper program that

 runs ikiwiki to update a given wiki. The wrapper can in turn be made suid,
 for example to be used in a [[post-commit]] hook by people who cannot write
 to the html pages, etc.
 runs ikiwiki to update a given wiki. The wrapper can in turn be made suid,
 for example to be used in a [[post-commit]] hook by people who cannot write
 to the html pages, etc.


@@ -111,9 +118,13 @@ been no problem yet.
 ## shell exploits
 
 ikiwiki does not expose untrusted data to the shell. In fact it doesn't use
 ## shell exploits
 
 ikiwiki does not expose untrusted data to the shell. In fact it doesn't use

-system() at all, and the only use of backticks is on data supplied by the
-wiki admin and untainted filenames. And it runs with taint checks on of
-course..
+`system(3)` at all, and the only use of backticks is on data supplied by the
+wiki admin and untainted filenames. 
+
+Ikiwiki was developed and used for a long time with perl's taint checking
+turned on as a second layer of defense against shell and other exploits. Due
+to a strange [bug](http://bugs.debian.org/411786) in perl, taint checking
+is currently disabled for production builds of ikiwiki.

 
 ## cgi data security
 
 
 ## cgi data security
 


@@ -134,15 +145,15 @@ file not be world readable.
 
 ## cgi password security
 
 
 ## cgi password security
 

-Login to the wiki involves sending a password in cleartext over the net.
-Cracking the password only allows editing the wiki as that user though.
-If you care, you can use https, I suppose. If you do use https either for
-all of the wiki, or just the cgi access, then consider using the sslcookie
-option.
+Login to the wiki using [[plugins/passwordauth]] involves sending a password
+in cleartext over the net. Cracking the password only allows editing the wiki
+as that user though. If you care, you can use https, I suppose. If you do use
+https either for all of the wiki, or just the cgi access, then consider using
+the sslcookie option. Using [[plugins/openid]] is a potentially better option.

 
 ## XSS holes in CGI output
 
 
 ## XSS holes in CGI output
 

-ikiwiki has not yet been audited to ensure that all cgi script input/output
+ikiwiki has been audited to ensure that all cgi script input/output

 is sanitised to prevent XSS attacks. For example, a user can't register
 with a username containing html code (anymore).
 
 is sanitised to prevent XSS attacks. For example, a user can't register
 with a username containing html code (anymore).
 


@@ -151,10 +162,11 @@ closed though.
 
 ## HTML::Template security
 
 
 ## HTML::Template security
 

-If the [[plugins/template]] plugin is enabled, users can modify templates
-like any other part of the wiki. This assumes that HTML::Template is secure
+If the [[plugins/template]] plugin is enabled, all users can modify templates
+like any other part of the wiki. Some trusted users can modify templates
+without it too. This assumes that HTML::Template is secure

 when used with untrusted/malicious templates. (Note that includes are not
 when used with untrusted/malicious templates. (Note that includes are not

-allowed, so that's not a problem.)
+allowed.)

 
 ----
 
 
 ----
 


@@ -341,7 +353,138 @@ There are at least two configurations where this is exploitable:
   notice.
 
 This security hole was discovered on 26 November 2007 and fixed the same
   notice.
 
 This security hole was discovered on 26 November 2007 and fixed the same

-da with the release of ikiwiki 2.14. I recommend upgrading to this version
+day with the release of ikiwiki 2.14. I recommend upgrading to this version

 if your wiki can be committed to by third parties. Alternatively, don't use
 a trailing slash in the srcdir, and avoid the (unusual) configurations that
 allow the security hole to be exploited.
 if your wiki can be committed to by third parties. Alternatively, don't use
 a trailing slash in the srcdir, and avoid the (unusual) configurations that
 allow the security hole to be exploited.

+
+## javascript insertion via uris
+
+The htmlscrubber did not block javascript in uris. This was fixed by adding
+a whitelist of valid uri types, which does not include javascript. 
+([[!cve CVE-2008-0809]]) Some urls specifyable by the meta plugin could also
+theoretically have been used to inject javascript; this was also blocked
+([[!cve CVE-2008-0808]]).
+
+This hole was discovered on 10 February 2008 and fixed the same day
+with the release of ikiwiki 2.31.1. (And a few subsequent versions..)
+A fix was also backported to Debian etch, as version 1.33.4. I recommend
+upgrading to one of these versions if your wiki can be edited by third
+parties.
+
+## Cross Site Request Forging
+
+Cross Site Request Forging could be used to constuct a link that would
+change a logged-in user's password or other preferences if they clicked on
+the link. It could also be used to construct a link that would cause a wiki
+page to be modified by a logged-in user. ([[!cve CVE-2008-0165]])
+
+These holes were discovered on 10 April 2008 and fixed the same day with
+the release of ikiwiki 2.42. A fix was also backported to Debian etch, as
+version 1.33.5. I recommend upgrading to one of these versions.
+
+## Cleartext passwords
+
+Until version 2.48, ikiwiki stored passwords in cleartext in the `userdb`.
+That risks exposing all users' passwords if the file is somehow exposed. To
+pre-emtively guard against that, current versions of ikiwiki store password
+hashes (using Eksblowfish).
+
+If you use the [[plugins/passwordauth]] plugin, I recommend upgrading to
+ikiwiki 2.48, installing the [[!cpan Authen::Passphrase]] perl module, and running
+`ikiwiki-transition hashpassword` to replace all existing cleartext passwords
+with strong blowfish hashes. 
+
+You might also consider changing to [[plugins/openid]], which does not 
+require ikiwiki deal with passwords at all, and does not involve users sending
+passwords in cleartext over the net to log in, either.
+
+## Empty password security hole
+
+This hole allowed ikiwiki to accept logins using empty passwords, to openid
+accounts that didn't use a password. It was introduced in version 1.34, and
+fixed in version 2.48. The [bug](http://bugs.debian.org/483770) was
+discovered on 30 May 2008 and fixed the same day. ([[!cve CVE-2008-0169]])
+
+I recommend upgrading to 2.48 immediatly if your wiki allows both password
+and openid logins.
+
+## Malformed UTF-8 DOS
+
+Feeding ikiwiki page sources containing certian forms of malformed UTF-8
+can cause it to crash. This can potentially be used for a denial of service
+attack.
+
+intrigeri discovered this problem on 12 Nov 2008 and a patch put in place
+later that day, in version 2.70. The fix was backported to testing as version
+2.53.3, and to stable as version 1.33.7.
+
+## Insufficient blacklisting in teximg plugin
+
+Josh Triplett discovered on 28 Aug 2009 that the teximg plugin's
+blacklisting of insecure TeX commands was insufficient; it could be
+bypassed and used to read arbitrary files. This was fixed by
+enabling TeX configuration options that disallow unsafe TeX commands.
+The fix was released on 30 Aug 2009 in version 3.1415926, and was
+backported to stable in version 2.53.4. If you use the teximg plugin,
+I recommend upgrading. ([[!cve CVE-2009-2944]])
+
+## javascript insertion via svg uris
+
+Ivan Shmakov pointed out that the htmlscrubber allowed `data:image/*` urls,
+including `data:image/svg+xml`. But svg can contain javascript, so that is
+unsafe.
+
+This hole was discovered on 12 March 2010 and fixed the same day
+with the release of ikiwiki 3.20100312.
+A fix was also backported to Debian etch, as version 2.53.5. I recommend
+upgrading to one of these versions if your wiki can be edited by third
+parties.
+
+## javascript insertion via insufficient htmlscrubbing of comments
+
+Kevin Riggle noticed that it was not possible to configure
+`htmlscrubber_skip` to scrub comments while leaving unscubbed the text
+of eg, blog posts. Confusingly, setting it to "* and !comment(*)" did not
+scrub comments.
+
+Additionally, it was discovered that comments' html was never scrubbed during
+preview or moderation of comments with such a configuration.
+
+These problems were discovered on 12 November 2010 and fixed the same
+hour with the release of ikiwiki 3.20101112. ([[!cve CVE-2010-1673]])
+
+## javascript insertion via insufficient checking in comments
+
+Dave B noticed that attempting to comment on an illegal page name could be
+used for an XSS attack.
+
+This hole was discovered on 22 Jan 2011 and fixed the same day with
+the release of ikiwiki 3.20110122. A fix was backported to Debian squeeze,
+as version 3.20100815.5. An upgrade is recommended for sites
+with the comments plugin enabled. ([[!cve CVE-2011-0428]])
+
+## possible javascript insertion via insufficient htmlscrubbing of alternate stylesheets
+
+Giuseppe Bilotta noticed that 'meta stylesheet` directives allowed anyone
+who could upload a malicious stylesheet to a site to add it to a
+page as an alternate stylesheet, or replacing the default stylesheet.
+
+This hole was discovered on 28 Mar 2011 and fixed the same hour with
+the release of ikiwiki 3.20110328. A fix was backported to Debian squeeze,
+as version 3.20100815.6. An upgrade is recommended for sites that have
+untrusted committers, or have the attachments plugin enabled.
+([[!cve CVE-2011-1401]])
+
+## tty hijacking via ikiwiki-mass-rebuild
+
+Ludwig Nussel discovered a way for users to hijack root's tty when
+ikiwiki-mass-rebuild was run. Additionally, there was some potential
+for information disclosure via symlinks. ([[!cve CVE-2011-1408]])
+
+This hole was disconvered on 8 June 2011 and fixed the same day with
+the release of ikiwiki 3.20110608. Note that the fix is dependant on
+a version of su that has a similar hole fixed; [[!debbug 628843]]
+tracks fixing the hole in Debian's su. An upgrade is a must for any
+sites that have `ikiwiki-update-wikilist` installed suid (not the default),
+and whose admins run `ikiwiki-mass-rebuild`.