-Let's do an ikiwiki security analysis.
-
If you are using ikiwiki to render pages that only you can edit, do not
generate any wrappers, and do not use the cgi, then there are no more
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.
+If you find a new security vulnerability, please email the maintainers
+privately instead of listing it in a public bug tracker, so that we can
+arrange for coordinated disclosure when a fix is available. The maintainers
+are [[Joey Hess|joey]] (<joey@kitenet.net>),
+[[Simon McVittie|smcv]] (<smcv@debian.org>)
+and [[Amitai Schleier|schmonz]] (<schmonz-web-ikiwiki@schmonz.com>).
+
[[!toc levels=2]]
----
## 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.
----
## setup files
Setup files are not safe to keep in the same revision control repository
-with the rest of the wiki. Just don't do it. [[ikiwiki.setup]] is *not*
-used as the setup file for this wiki, BTW.
+with the rest of the wiki. Just don't do it.
## page locking can be bypassed via direct commits
for example to be used in a [[post-commit]] hook by people who cannot write
to the html pages, etc.
-If the wrapper script is made suid, then any bugs in this wrapper would be
+If the wrapper program is made suid, then any bugs in this wrapper would be
security holes. The wrapper is written as securely as I know how, is based
on code that has a history of security use long before ikiwiki, and there's
been no problem yet.
## 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
-allowed, so that's not a problem.)
+allowed.)
----
some security notes for them.
* The [[plugins/img]] plugin assumes that imagemagick/perlmagick are secure
- from malformed image attacks. Imagemagick has had security holes in the
+ from malformed image attacks for at least the formats listed in
+ `img_allowed_formats`. Imagemagick has had security holes in the
past. To be able to exploit such a hole, a user would need to be able to
upload images to the wiki.
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
+([[!debcve 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]]).
+([[!debcve 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..)
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]])
+page to be modified by a logged-in user. ([[!debcve 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
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]])
+discovered on 30 May 2008 and fixed the same day. ([[!debcve 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. ([[!debcve 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. ([[!debcve 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. ([[!debcve 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.
+([[!debcve 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. ([[!debcve CVE-2011-1408]])
+
+This hole was discovered 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. Version 4.1.5 of the shadow
+package contains the fixed su; [[!debbug 628843]] tracks fixing the hole in
+Debian. 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`.
+
+## javascript insertion via meta tags
+
+Raúl Benencia discovered an additional XSS exposure in the meta plugin.
+([[!debcve CVE-2012-0220]])
+
+This hole was discovered on 16 May 2012 and fixed the same day with
+the release of ikiwiki 3.20120516. A fix was backported to Debian squeeze,
+as version 3.20100815.9. An upgrade is recommended for all sites.
+
+## XSS via openid selector
+
+Raghav Bisht discovered this XSS in the openid selector. ([[!debcve CVE-2015-2793]])
+
+The hole was reported on March 24th, a fix was developed on March 27th,
+and the fixed version 3.20150329 was released on the 29th. A fix was backported
+to Debian jessie as version 3.20141016.2 and to Debian wheezy as version
+3.20120629.2. An upgrade is recommended for sites using CGI and openid.
+
+## XSS via error messages
+
+CGI error messages did not escape HTML meta-characters, potentially
+allowing an attacker to carry out cross-site scripting by directing a
+user to a URL that would result in a crafted ikiwiki error message. This
+was discovered on 4 May by the ikiwiki developers, and the fixed version
+3.20160506 was released on 6 May. The same fixes were backported to Debian
+8 "jessie" in version 3.20141016.3. A backport to Debian 7 "wheezy" is
+in progress.
+
+An upgrade is recommended for sites using
+the CGI. ([[!debcve CVE-2016-4561]], OVE-20160505-0012)
+
+## ImageMagick CVE-2016–3714 ("ImageTragick")
+
+ikiwiki 3.20160506 and 3.20141016.3 attempt to mitigate
+[[!debcve CVE-2016-3714]], and any
+future ImageMagick vulnerabilities that resemble it, by restricting the
+image formats that the [[ikiwiki/directive/img]] directive is willing to
+resize. An upgrade is recommended for sites where an untrusted user is
+able to attach images. Upgrading ImageMagick to a version where
+CVE-2016-3714 has been fixed is also recommended, but at the time of
+writing no such version is available.
+
+## Perl CVE-2016-1238 (current working directory in search path)
+
+ikiwiki 3.20160728 attempts to mitigate [[!debcve CVE-2016-1238]] by
+removing `'.'` from the Perl library search path. An attacker with write
+access to ikiwiki's current working directory could potentially use this
+vulnerability to execute arbitrary Perl code. An upgrade is recommended
+for sites where an untrusted user is able to attach files with arbitrary
+names and/or run a setuid ikiwiki wrapper with a working directory of
+their choice.
+
+## <span id="cve-2016-9645">Editing restriction bypass for git revert</span>
+
+intrigeri discovered that a web or git user could revert a change to a
+page they are not allowed to edit, if the change being reverted was made
+before the page was moved from a location where that user had permission
+to edit it. For example, if a file is moved from `drafts/policy.mdwn`
+(editable by less-trusted users) to `policy.mdwn` (only editable
+by more-trusted users), a less-trusted user could revert a change
+that was made to `drafts/policy.mdwn` prior to that move, and it would
+result in `policy.mdwn` being altered.
+
+This affects sites with the `git` VCS and the `recentchanges` plugin,
+which are both used in most ikiwiki installations.
+
+This bug was reported on 2016-12-17. A partially fixed version
+3.20161219 was released on 2016-12-19, but the solution used in that
+version was not effective with git versions older than 2.8.0.
+A more complete fix was released on 2016-12-29 in version 3.20161229,
+with fixes backported to Debian 8 in version 3.20141016.4.
+
+([[!debcve CVE-2016-10026]] represents the original vulnerability.
+[[!debcve CVE-2016-9645]]/OVE-20161226-0002 represents the vulnerability
+in 3.20161219 caused by the incomplete fix.)
+
+## <span id="cve-2016-9646">Commit metadata forgery via CGI::FormBuilder context-dependent APIs</span>
+
+When CGI::FormBuilder->field("foo") is called in list context (and
+in particular in the arguments to a subroutine that takes named
+arguments), it can return zero or more values for foo from the CGI
+request, rather than the expected single value. This breaks the usual
+Perl parsing convention for named arguments, similar to CVE-2014-1572
+in Bugzilla (which was caused by a similar API design issue in CGI.pm).
+
+In ikiwiki, this appears to have been exploitable in two places, both
+of them relatively minor:
+
+* in the comments plugin, an attacker who was able to post a comment
+ could give it a user-specified author and author-URL even if the wiki
+ configuration did not allow for that, by crafting multiple values
+ for other fields
+* in the editpage plugin, an attacker who was able to edit a page
+ could potentially forge commit authorship (attribute their edit to
+ someone else) by crafting multiple values for the rcsinfo field
+
+This was fixed in ikiwiki 3.20161229, with fixes backported to Debian 8
+in version 3.20141016.4.
+
+([[!debcve CVE-2016-9646]]/OVE-20161226-0001)
+
+## <span id="cve-2017-0356">Authentication bypass via repeated parameters</span>
+
+The ikiwiki maintainers discovered further flaws similar to CVE-2016-9646
+in the passwordauth plugin's use of CGI::FormBuilder, with a more
+serious impact:
+
+* An attacker who can log in to a site with a password can log in
+ as a different and potentially more privileged user.
+* An attacker who can create a new account can set arbitrary fields
+ in the user database for that account.
+
+This was fixed in ikiwiki 3.20170111, with fixes backported to Debian 8
+in version 3.20141016.4.
+
+([[!debcve CVE-2017-0356]]/OVE-20170111-0001)
+
+## <span id="cve-2019-9187">Server-side request forgery via aggregate plugin</span>
+
+The ikiwiki maintainers discovered that the [[plugins/aggregate]] plugin
+did not use [[!cpan LWPx::ParanoidAgent]]. On sites where the
+aggregate plugin is enabled, authorized wiki editors could tell ikiwiki
+to fetch potentially undesired URIs even if LWPx::ParanoidAgent was
+installed:
+
+* local files via `file:` URIs
+* other URI schemes that might be misused by attackers, such as `gopher:`
+* hosts that resolve to loopback IP addresses (127.x.x.x)
+* hosts that resolve to RFC 1918 IP addresses (192.168.x.x etc.)
+
+This could be used by an attacker to publish information that should not have
+been accessible, cause denial of service by requesting "tarpit" URIs that are
+slow to respond, or cause undesired side-effects if local web servers implement
+["unsafe"](https://tools.ietf.org/html/rfc7231#section-4.2.1) GET requests.
+([[!debcve CVE-2019-9187]])
+
+Additionally, if the LWPx::ParanoidAgent module was not installed, the
+[[plugins/blogspam]], [[plugins/openid]] and [[plugins/pinger]] plugins
+would fall back to [[!cpan LWP]], which is susceptible to similar attacks.
+This is unlikely to be a practical problem for the blogspam plugin because
+the URL it requests is under the control of the wiki administrator, but
+the openid plugin can request URLs controlled by unauthenticated remote
+users, and the pinger plugin can request URLs controlled by authorized
+wiki editors.
+
+This is addressed in ikiwiki 3.20190228 as follows, with the same fixes
+backported to Debian 9 in version 3.20170111.1:
+
+* URI schemes other than `http:` and `https:` are not accepted, preventing
+ access to `file:`, `gopher:`, etc.
+
+* If a proxy is [[configured in the ikiwiki setup file|tips/using_a_proxy]],
+ it is used for all outgoing `http:` and `https:` requests. In this case
+ the proxy is responsible for blocking any requests that are undesired,
+ including loopback or RFC 1918 addresses.
+
+* If a proxy is not configured, and LWPx::ParanoidAgent is installed,
+ it will be used. This prevents loopback and RFC 1918 IP addresses, and
+ sets a timeout to avoid denial of service via "tarpit" URIs.
+
+* Otherwise, the ordinary LWP user-agent will be used. This allows requests
+ to loopback and RFC 1918 IP addresses, and has less robust timeout
+ behaviour. We are not treating this as a vulnerability: if this
+ behaviour is not acceptable for your site, please make sure to install
+ LWPx::ParanoidAgent or disable the affected plugins.