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Security Alert CVE-2014-7236: Remote Perl code execution with query string to debug TWiki plugins
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This advisory alerts you of a potential security issue with your TWiki installation: The
debugenableplugins
request parameter allows arbitrary Perl code execution.
Vulnerable Software Version
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 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 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:
my $p = $this->{module};
eval "use $p;";
Countermeasures
- Apply hotfix (see patch below).
- Upgrade to the latest patched production release TWiki-6.0.1 (TWikiRelease06x00x01)
Hotfix for TWiki Production Release 6.0.0
Affected file:
twiki/lib/TWiki/Plugins.pm
Patch to sanitize the
debugenableplugins
parameter:
--- 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]+/,
This patch is handled at
TWikibug:Item7558.
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.
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
Action Plan with Timeline
External Links
--
Peter Thoeny - 2014-10-07
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