Remote Perl code execution with query string to debug TWiki plugins

影响版本：

* TWiki-6.0.0 (TWikiRelease06x00x00)
* TWiki-5.1.x (TWikiRelease05x01x00 to TWikiRelease05x01x04)
* TWiki-5.0.x (TWikiRelease05x00x00 to TWikiRelease05x00x02)
* TWiki-4.3.x (TWikiRelease04x03x00 to TWikiRelease04x03x02)
* TWiki-4.2.x (TWikiRelease04x02x00 to TWikiRelease04x02x04)
* TWiki-4.1.x (TWikiRelease04x01x00 to TWikiRelease04x01x02)
* TWiki-4.0.x (TWikiRelease04x00x00 to TWikiRelease04x00x05)

测试方法：

http://www.example.com/do/view/Main/WebHome?debugenableplugins=BackupRestorePlugin%3bprint("Content-Type:text/html\r\n\r\nVulnerable!")%3bexit

修复方式：

twiki/lib/TWiki/Plugins.pm

Patch to sanitize the 'debugenableplugins' parameter:

=======( 8>< CUT )===============================================
--- TWiki/Plugins.pm.save1   2014-01-09 02:10:56.000000000 -0500
+++ TWiki/Plugins.pm   2014-10-01 20:30:36.000000000 -0400
@@ -186,8 +186,11 @@

     unless( $allDisabled ) {
         if ( $query && defined( $query->param( 'debugenableplugins' ))) {
-            @pluginList = split( /[,\s]+/,
-                                 $query->param( 'debugenableplugins' ));
+            @pluginList =
+              grep { /Plugin$/ }
+              map { s/[^a-zA-Z0-9]//go; $_ } # Item7558: Sanitize parameter
+              split( /[,\s]+/, $query->param( 'debugenableplugins' ));
+
         } else {
             if( $TWiki::cfg{PluginsOrder} ) {
                 foreach my $plugin( split( /[,\s]+/,
=======( 8>< CUT )===============================================

Source: http://seclists.org/fulldisclosure/2014/Oct/44

TWiki Security Alert CVE-2014-7236: Remote Perl code execution with query string to debug TWiki plugins

From: Peter Thoeny <peter09 () thoeny org>

Date: Thu, 9 Oct 2014 07:26:56 -0700

This is an advisory for TWiki administrators: The debugenableplugins request parameter allows arbitrary Perl code
execution.
TWiki ( http://twiki.org ) is an Open Source Enterprise Wiki and Web Application Platform used by millions of people.
   * Vulnerable Software Version
   * Attack Vectors
   * Impact
   * Severity Level
   * MITRE Name for this Vulnerability
   * Details
   * Countermeasures
   * Hotfix for TWiki Production Release 6.0.0
   * Hotfix for Older Affected TWiki Releases
   * Verify Hotfix
   * Authors and Credits
   * Action Plan with Timeline
   * External Links
   * Feedback
---++ Vulnerable Software Version
   * TWiki-6.0.0 (TWikiRelease06x00x00)
   * TWiki-5.1.x (TWikiRelease05x01x00 to TWikiRelease05x01x04)
   * TWiki-5.0.x (TWikiRelease05x00x00 to TWikiRelease05x00x02)
   * TWiki-4.3.x (TWikiRelease04x03x00 to TWikiRelease04x03x02)
   * TWiki-4.2.x (TWikiRelease04x02x00 to TWikiRelease04x02x04)
   * TWiki-4.1.x (TWikiRelease04x01x00 to TWikiRelease04x01x02)
   * TWiki-4.0.x (TWikiRelease04x00x00 to TWikiRelease04x00x05)
---++ Attack Vectors
Using an HTTP GET request towards a TWiki server, add a specially crafted 'debugenableplugins' request parameter to
TWiki's view script (typically port 80/TCP). Prior authentication may or may not be necessary.
---++ Impact
A remote attacker can execute arbitrary Perl code to view and modify any file the webserver user has access to.
---++ Severity Level
The TWiki SecurityTeam triaged this issue as documented in TWikiSecurityAlertProcess [1] and assigned the following
severity level:
   * Severity 1 issue: The web server can be compromised
---++ MITRE Name for this Vulnerability
The Common Vulnerabilities and Exposures project has assigned the name CVE-2014-7236 [7] to this vulnerability.
---++ Details
It is possible to execute arbitrary Perl code by adding a =debugenableplugins= parameter with a specially crafted
value. Example: http://www.example.com/do/view/Main/WebHome?debugenableplugins=BackupRestorePlugin%3bprint("Content-Type:text/html\r\n\r\nVulnerable!")%3bexit
The TWiki site is vulnerable if you see a page with text "Vulnerable!".
__Background:__
TWiki allows enabling specific plugins for debug purposes using a 'debugenableplugins' parameter that lists the plugins
to enable. In order to support this dynamic loading of plugins, TWiki inserts the plugin name into the following Perl
=eval= statement without sanitizing the plugin name:
<verbatim>
my $p = $this->{module};
eval "use $p;";
</verbatim>
---++ Countermeasures
   * Apply hotfix (see patch below).
   * Upgrade to the latest patched production release TWiki-6.0.1 (TWikiRelease06x00x01) [2]
---++ Hotfix for TWiki Production Release 6.0.0
Apply the patch listed in the TWiki bug item at TWikibug:Item7558 [8]. The patch is also listed here, but due to
whitespace changes in e-mail it is not recommended to use below patch.
NOTE: In case you use a Perl accelerator make sure to clear the script cache. For example, in case of SpeedyCGI remove
the speedy cache (tmp/speedy.*) before restarting Apache.
Affected file: twiki/lib/TWiki/Plugins.pm
Patch to sanitize the 'debugenableplugins' parameter:
=======( 8>< CUT )===============================================
--- TWiki/Plugins.pm.save1   2014-01-09 02:10:56.000000000 -0500
+++ TWiki/Plugins.pm   2014-10-01 20:30:36.000000000 -0400
@@ -186,8 +186,11 @@

     unless( $allDisabled ) {
         if ( $query && defined( $query->param( 'debugenableplugins' ))) {
-            @pluginList = split( /[,\s]+/,
-                                 $query->param( 'debugenableplugins' ));
+            @pluginList =
+              grep { /Plugin$/ }
+              map { s/[^a-zA-Z0-9]//go; $_ } # Item7558: Sanitize parameter
+              split( /[,\s]+/, $query->param( 'debugenableplugins' ));
+
         } else {
             if( $TWiki::cfg{PluginsOrder} ) {
                 foreach my $plugin( split( /[,\s]+/,
=======( 8>< CUT )===============================================
---++ Hotfix for Older Affected TWiki Releases
Apply above patch (line numbers may vary).
---++ Verify Hotfix
To verify the patch add the following parameter to any TWiki topic:
?debugenableplugins=BackupRestorePlugin%3bprint("Content-Type:text/html\r\n\r\nVulnerable!")%3bexit
The site is vulnerable if a page is returned with text "Vulnerable!"
---++ Authors and Credits
   * Credit to Netanel Rubin (netanelr[at]checkpoint.com) for disclosing the issue to the twiki-security () lists
sourceforge netmailing list
   * PeterThoeny for creating the fix, patch and advisory
   * HideyoImazu for creating the TWiki-6.0.1 production release [2]
---++ Action Plan with Timeline
   * 2014-10-01 - Netanel Rubin of Check Point Software discloses issue to TWikiSecurityMailingList [4]
   * 2014-10-01 - developer verifies issue - PeterThoeny
   * 2014-10-01 - developer fixes code - PeterThoeny
   * 2014-10-05 - developer creates new TWiki-6.0.1 patch release [2] with fix - HideyoImazu
   * 2014-10-06 - security team creates advisory with hotfix - PeterThoeny
   * 2014-10-07 - send alert to TWikiAnnounceMailingList [5] and TWikiDevMailingList [6] - PeterThoeny
   * 2014-10-09 - publish advisory in Codev web and update all related topics - PeterThoeny
   * 2014-10-09 - issue a public security advisory to fulldisclosure[at]seclists.org, cert[at]cert.org,
vuln[at]secunia.com, bugs[at]securitytracker.com, submissions[at]packetstormsecurity.org - PeterThoeny
---++ External Links
[1]: http://twiki.org/cgi-bin/view/Codev/TWikiSecurityAlertProcess [2]: http://twiki.org/cgi-bin/view/Codev/TWikiRelease06x00x01 [3]: http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2014-7236 (will be created on 2014-10-09)
[4]: http://twiki.org/cgi-bin/view/Codev/TWikiSecurityMailingList [5]: http://twiki.org/cgi-bin/view/Codev/TWikiAnnounceMailingList [6]: http://twiki.org/cgi-bin/view/Codev/TWikiDevMailingList [7]: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7236 - CVE on MITRE.org
[8]: http://develop.twiki.org/~twiki4/cgi-bin/view/Bugs/Item7558 ---++ Feedback
Please provide feedback at the security alert topic, http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2014-7236 once it exists (this topic will be created on Mon, 2014-10-09).
Please send an e-mail to twiki-security () lists sourceforge net if you have any questions before Monday.
-- Peter Thoeny - 2014-10-09
--

Peter Thoeny     - Peter09[at]Thoeny.org http://bit.ly/MrTWiki - consulting on enterprise collaboration http://TWiki.org - is your team already TWiki enabled?
Knowledge cannot be managed, it can be discovered and shared
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