From: Joey Hess Date: Thu, 10 Apr 2008 20:35:30 +0000 (-0400) Subject: Fix CSRF attacks against the preferences and edit forms. Closes: #475445 X-Git-Url: https://sipb.mit.edu/gitweb.cgi/ikiwiki.git/commitdiff_plain/72b5ef2c5fb01751992c9400afe2690da5df611f?ds=inline Fix CSRF attacks against the preferences and edit forms. Closes: #475445 The fix involved embedding the session id in the forms, and not allowing the forms to be submitted if the embedded id does not match the session id. In the case of the preferences form, if the session id is not embedded, then the CGI parameters are cleared. This avoids a secondary attack where the link to the preferences form prefills password or other fields, and the user hits "submit" without noticing these prefilled values. In the case of the editpage form, the anonok plugin can allow anyone to edit, and so I chose not to guard against CSRF attacks against users who are not logged in. Otherwise, it also embeds the session id and checks it. For page editing, I assume that the user will notice if content or commit message is changed because of CGI parameters, and won't blndly hit save page. So I didn't block those CGI paramters. (It's even possible to use those CGI parameters, for good, not for evil, I guess..) The only other CSRF attack I can think of in ikiwiki involves the poll plugin. It's certianly possible to set up a link that causes the user to unknowingly vote in a poll. However, the poll plugin is not intended to be used for things that people would want to attack, since anyone can after all edit the poll page and fill in any values they like. So this "attack" is ignorable. --- diff --git a/IkiWiki/CGI.pm b/IkiWiki/CGI.pm index 470677088..65136a269 100644 --- a/IkiWiki/CGI.pm +++ b/IkiWiki/CGI.pm @@ -161,8 +161,18 @@ sub cgi_prefs ($$) { #{{{ my $session=shift; needsignin($q, $session); - decode_cgi_utf8($q); + + # The session id is stored on the form and checked to + # guard against CSRF. + my $sid=$q->param('sid'); + if (! defined $sid) { + $q->delete_all; + } + elsif ($sid ne $session->id) { + error(gettext("Your login session has expired.")); + } + eval q{use CGI::FormBuilder}; error($@) if $@; my $form = CGI::FormBuilder->new( @@ -193,7 +203,10 @@ sub cgi_prefs ($$) { #{{{ buttons => $buttons); }); - $form->field(name => "do", type => "hidden"); + $form->field(name => "do", type => "hidden", value => "prefs", + force => 1); + $form->field(name => "sid", type => "hidden", value => $session->id, + force => 1); $form->field(name => "email", size => 50, fieldset => "preferences"); $form->field(name => "banned_users", size => 50, fieldset => "admin"); @@ -241,11 +254,11 @@ sub cgi_prefs ($$) { #{{{ sub cgi_editpage ($$) { #{{{ my $q=shift; my $session=shift; - - my @fields=qw(do rcsinfo subpage from page type editcontent comments); - my @buttons=("Save Page", "Preview", "Cancel"); decode_cgi_utf8($q); + + my @fields=qw(do rcsinfo subpage from page type editcontent comments); + my @buttons=("Save Page", "Preview", "Cancel"); eval q{use CGI::FormBuilder}; error($@) if $@; my $form = CGI::FormBuilder->new( @@ -316,6 +329,8 @@ sub cgi_editpage ($$) { #{{{ } $form->field(name => "do", type => 'hidden'); + $form->field(name => "sid", type => "hidden", value => $session->id, + force => 1); $form->field(name => "from", type => 'hidden'); $form->field(name => "rcsinfo", type => 'hidden'); $form->field(name => "subpage", type => 'hidden'); @@ -474,6 +489,16 @@ sub cgi_editpage ($$) { #{{{ else { # save page check_canedit($page, $q, $session); + + # The session id is stored on the form and checked to + # guard against CSRF. But only if the user is logged in, + # as anonok can allow anonymous edits. + if (defined $session->param("name")) { + my $sid=$q->param('sid'); + if (! defined $sid || $sid ne $session->id) { + error(gettext("Your login session has expired.")); + } + } my $exists=-e "$config{srcdir}/$file"; diff --git a/debian/changelog b/debian/changelog index 613640f60..9085d97cb 100644 --- a/debian/changelog +++ b/debian/changelog @@ -3,6 +3,9 @@ ikiwiki (2.42) UNRELEASED; urgency=low * aggregate: Correct a mistake in the code that dummy up a guid for feeds lacking one. * inline: Correct handling of urls relative to baseurl in feeds. + * Fix CSRF attacks against the preferences and edit forms. The fix involved + embedding the session id in the forms, and not allowing the forms to be + submitted if the embedded id does not match the session id. Closes: #475445 -- Joey Hess Thu, 03 Apr 2008 02:35:39 -0400 diff --git a/doc/security.mdwn b/doc/security.mdwn index 373f64557..29ae7d4b3 100644 --- a/doc/security.mdwn +++ b/doc/security.mdwn @@ -366,3 +366,14 @@ 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. + +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 1.33.4. I recommend upgrading to one of these versions. diff --git a/po/ikiwiki.pot b/po/ikiwiki.pot index a3f7cafcb..5e7e4b4d4 100644 --- a/po/ikiwiki.pot +++ b/po/ikiwiki.pot @@ -8,7 +8,7 @@ msgid "" msgstr "" "Project-Id-Version: PACKAGE VERSION\n" "Report-Msgid-Bugs-To: \n" -"POT-Creation-Date: 2008-03-29 21:01-0400\n" +"POT-Creation-Date: 2008-04-10 16:18-0400\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: LANGUAGE \n" @@ -24,46 +24,50 @@ msgstr "" msgid "login failed, perhaps you need to turn on cookies?" msgstr "" -#: ../IkiWiki/CGI.pm:184 +#: ../IkiWiki/CGI.pm:173 ../IkiWiki/CGI.pm:499 +msgid "Your login session has expired." +msgstr "" + +#: ../IkiWiki/CGI.pm:194 msgid "Login" msgstr "" -#: ../IkiWiki/CGI.pm:185 +#: ../IkiWiki/CGI.pm:195 msgid "Preferences" msgstr "" -#: ../IkiWiki/CGI.pm:186 +#: ../IkiWiki/CGI.pm:196 msgid "Admin" msgstr "" -#: ../IkiWiki/CGI.pm:235 +#: ../IkiWiki/CGI.pm:248 msgid "Preferences saved." msgstr "" -#: ../IkiWiki/CGI.pm:293 +#: ../IkiWiki/CGI.pm:306 #, perl-format msgid "%s is not an editable page" msgstr "" -#: ../IkiWiki/CGI.pm:395 ../IkiWiki/Plugin/brokenlinks.pm:24 +#: ../IkiWiki/CGI.pm:410 ../IkiWiki/Plugin/brokenlinks.pm:24 #: ../IkiWiki/Plugin/inline.pm:265 ../IkiWiki/Plugin/opendiscussion.pm:17 #: ../IkiWiki/Plugin/orphans.pm:28 ../IkiWiki/Render.pm:95 #: ../IkiWiki/Render.pm:172 msgid "discussion" msgstr "" -#: ../IkiWiki/CGI.pm:451 +#: ../IkiWiki/CGI.pm:466 #, perl-format msgid "creating %s" msgstr "" -#: ../IkiWiki/CGI.pm:469 ../IkiWiki/CGI.pm:487 ../IkiWiki/CGI.pm:497 -#: ../IkiWiki/CGI.pm:531 ../IkiWiki/CGI.pm:576 +#: ../IkiWiki/CGI.pm:484 ../IkiWiki/CGI.pm:512 ../IkiWiki/CGI.pm:522 +#: ../IkiWiki/CGI.pm:556 ../IkiWiki/CGI.pm:601 #, perl-format msgid "editing %s" msgstr "" -#: ../IkiWiki/CGI.pm:666 +#: ../IkiWiki/CGI.pm:691 msgid "You are banned." msgstr "" @@ -222,7 +226,7 @@ msgstr "" msgid "Discussion" msgstr "" -#: ../IkiWiki/Plugin/inline.pm:491 +#: ../IkiWiki/Plugin/inline.pm:500 msgid "RPC::XML::Client not found, not pinging" msgstr "" diff --git a/templates/editpage.tmpl b/templates/editpage.tmpl index cf4950ead..b0bb0ecb9 100644 --- a/templates/editpage.tmpl +++ b/templates/editpage.tmpl @@ -41,6 +41,7 @@ together before saving. +