Security Alert: Denial-of-Service vulnerability in MAKETEXT macro

Attack Vectors

Editing wiki pages and HTTP POST requests towards a Foswiki server with enabled localization (typically port 80/TCP). Typically, prior authentication is necessary.

A crafted %MAKETEXT{}% macro can consume all memory leading to a possible system crash. Any user with the authority to edit a topic, comment on a topic, or execute the Foswiki rendering code (eg. The RenderPlugin) can take advantage of the vulnerability.

Impact

Exhaustion of system swap space and memory, leading to Denial of Service

A critical remote code execution vulnerability (SecurityAlert-CVE-2012-6329) is also addressed by the patches in this alert. Refer to that alert for further information.

Details

A crafted %MAKETEXT{}% macro can cause multiple issues:

• Execute arbitrary code on the server by passing unsanitized strings to Locale::Maketext. (CVE-2012-6329)
• Consume memory and swap space resulting in potential lockup or crash due to %<nop>MAKETEXT{}% not validating the parameter numbers supplied in the [_nnn] tokens. (CVE-2012-6330)
• Cause an exception within Foswiki, also due to invalid parameters in [_nnn] tokens

Countermeasures

One of the following should be done as soon as possible.

• Manually Apply hotfix (see patch below). or
• Apply the http://foswiki.org/Extensions/PatchItem12285Contrib to your Foswiki 1.1.x system (Does not apply to Foswiki 1.0.x) or
• The foswiki debian package has already been updated with the hotfix - use your preferred package management tool to update to foswiki 1.1.6-2

Note that Disable {UserInerfaceInternationalization} in your LocalSite.cfg will avoid the code execution vulnerability reported as SecurityAlert-CVE-2012-6329 but this other issue will still remain.

Upgrade to the latest patched production FoswikiRelease01x01x07 once released

The Foswiki patch fixes other issues with the %MAKETEXT% macro beyond the out of memory issue. Even with this patch installed, we recommend that a new Locale::Maketext is also upgraded to 1.23 or later

Hotfix for Foswiki Release 1.1.0 - 1.1.6

Install Extensions.PatchItem12285Contrib, and verify that the patch has been applied to lib/Foswiki/Macros/MAKETEXT.pm. The extension will attempt to apply two patches, and should report that 1 file was patched. Only one of the patches will match your system. This patch fixes both SecurityAlert-CVE-2012-6329 and SecurityAlert-CVE-2012-6330.

Running Post-install exit for PatchItem12285Contrib...
Processing /var/www/data/Foswiki-1.1.1/working/configure/patch/Item12285-001.patch
...
MD5 Matched - applying patch version Foswiki 1.1.0 - 1.1.2.
Update successful for /var/www/data/Foswiki-1.1.0/lib/Foswiki/Macros/MAKETEXT.pm
.
1 file patched
...
Processing /var/www/data/Foswiki-1.1.1/working/configure/patch/Item12285-002.patch
...
No files matched patch signatures

On a properly patched system, %MAKETEXT{" [_101] "}% should return an error. Excessive parameter number 101, MAKETEXT rejected.

Note that this Contrib will also install the PatchFoswikiContrib as a prerequisite. PatchFoswikiContrib patches the Extensions installer to accept the new style version strings used for modules released as of 1.1.6.

Hotfix for Foswiki Archived Release 1.0.0-1.0.10

This patch fixes both SecurityAlert-CVE-2012-6329 and SecurityAlert-CVE-2012-6330.

This release should be manually patched. In Foswiki.pm, in the sub MAKETEXT

--- Foswiki.pm  2010-01-17 09:16:20.000000000 -0500
+++ Foswiki.pm.new      2012-12-10 10:06:37.389129654 -0500
@@ -4200,6 +4200,9 @@
     $str =~
 s/~\[(\*,\_(\d+),[^,]+(,([^,]+))?)~\]/ $max = $2 if ($2 > $max); "[$1]"/ge;
 
+    return "Illegal parameter number" if ($max > 100);
+    $str =~ s#\\#\\\\#g;
+
     # get the args to be interpolated.
     my $argsStr = $params->{args} || "";
 

Manual patch for Foswiki Release 1.1.0 -> 1.1.2

Installing the PatchItem12285Contrib is the best way to patch your system - you can however see the patch we apply here. This patch fixes both SecurityAlert-CVE-2012-6329 and SecurityAlert-CVE-2012-6330:

~~~PATCH 72c86f0c71519caf6d26efbe174739f6  lib/Foswiki/Macros/MAKETEXT.pm (Foswiki 1.1.0 - 1.1.2)
--- /home/gac/Foswiki/Foswiki-1.1.0/lib/Foswiki/Macros/MAKETEXT.pm   2010-10-04 11:26:34.000000000 -0400
+++ lib/Foswiki/Macros/MAKETEXT.pm   2012-12-11 11:26:04.034507184 -0500
@@ -4,9 +4,19 @@
 use strict;
 use warnings;
 
+use Locale::Maketext;
+my $escape =
+  (      $Foswiki::cfg{UserInterfaceInternationalisation}
+      && $Locale::Maketext::VERSION
+      && $Locale::Maketext::VERSION < 1.23 );
+
 sub MAKETEXT {
     my ( $this, $params ) = @_;
 
+    my $max;
+    my $min;
+    my $param_error;
+
     my $str = $params->{_DEFAULT} || $params->{string} || "";
     return "" unless $str;
 
@@ -18,15 +28,22 @@
     $str =~ s/~~\[/~[/g;
     $str =~ s/~~\]/~]/g;
 
+    $max         = 0;
+    $min         = 1;
+    $param_error = 0;
+
     # unescape parameters and calculate highest parameter number:
-    my $max = 0;
-    $str =~ s/~\[(\_(\d+))~\]/ $max = $2 if ($2 > $max); "[$1]"/ge;
+    $str =~ s/~\[(\_(\d+))~\]/_validate($1, $2, $max, $min, $param_error)/ge;
     $str =~
-s/~\[(\*,\_(\d+),[^,]+(,([^,]+))?)~\]/ $max = $2 if ($2 > $max); "[$1]"/ge;
+s/~\[(\*,\_(\d+),[^,]+(,([^,]+))?)~\]/ _validate($1, $2, $max, $min, $param_error)/ge;
+    return $str if ($param_error);
 
     # get the args to be interpolated.
     my $argsStr = $params->{args} || "";
 
+    # Escape any escapes.
+    $str =~ s#\\#\\\\#g if ($escape);    # escape any escapes
+
     my @args = split( /\s*,\s*/, $argsStr );
 
     # fill omitted args with zeros
@@ -47,6 +64,26 @@
     return $result;
 }
 
+sub _validate {
+
+    #my ( $contents, $number, $max, $min, $param_error ) = @_
+
+    $_[2] = $_[1] if ( $_[1] > $_[2] );    # Record maximum param number
+    $_[3] = $_[1] if ( $_[1] < $_[3] );    # Record minimum param number
+
+    if ( $_[1] > 100 ) {
+        $_[4] = 1;                         # Set error flag
+        return
+"<span class=\"foswikiAlert\">Excessive parameter number $_[2], MAKETEXT rejected.</span>";
+    }
+    if ( $_[1] < 1 ) {
+        $_[4] = 1;                         # Set error flag
+        return
+"<span class=\"foswikiAlert\">Invalid parameter <code>\"$_[0]\"</code>, MAKETEXT rejected.</span>";
+    }
+    return "[$_[0]]";    # Return the complete bracket parameter without escapes
+}
+
 1;
 __END__
 Foswiki - The Free and Open Source Wiki, http://foswiki.org/
 

Manual patch for Foswiki Release 1.1.3 -> 1.1.6

Installing the PatchItem12285Contrib is the best way to patch your system - you can however see the patch we apply here This patch fixes both SecurityAlert-CVE-2012-6329 and SecurityAlert-CVE-2012-6330:

~~~PATCH 160f04fc478c5f9b81d2ef6c9e614074  lib/Foswiki/Macros/MAKETEXT.pm (Foswiki 1.1.3 - Foswiki 1.1.6)
--- lib/Foswiki/Macros/MAKETEXT.pm   2012-12-11 10:51:12.959268829 -0500
+++ lib/Foswiki/Macros/MAKETEXT.pm.new   2012-12-11 10:37:31.674486503 -0500
@@ -4,9 +4,19 @@
 use strict;
 use warnings;
 
+use Locale::Maketext;
+my $escape =
+  (      $Foswiki::cfg{UserInterfaceInternationalisation}
+      && $Locale::Maketext::VERSION
+      && $Locale::Maketext::VERSION < 1.23 );
+
 sub MAKETEXT {
     my ( $this, $params ) = @_;
 
+    my $max;
+    my $min;
+    my $param_error;
+
     my $str = $params->{_DEFAULT} || $params->{string} || "";
     return "" unless $str;
 
@@ -18,15 +28,22 @@
     $str =~ s/~~\[/~[/g;
     $str =~ s/~~\]/~]/g;
 
+    $max         = 0;
+    $min         = 1;
+    $param_error = 0;
+
     # unescape parameters and calculate highest parameter number:
-    my $max = 0;
-    $str =~ s/~\[(\_(\d+))~\]/ $max = $2 if ($2 > $max); "[$1]"/ge;
+    $str =~ s/~\[(\_(\d+))~\]/_validate($1, $2, $max, $min, $param_error)/ge;
     $str =~
-s/~\[(\*,\_(\d+),[^,]+(,([^,]+))?)~\]/ $max = $2 if ($2 > $max); "[$1]"/ge;
+s/~\[(\*,\_(\d+),[^,]+(,([^,]+))?)~\]/ _validate($1, $2, $max, $min, $param_error)/ge;
+    return $str if ($param_error);
 
     # get the args to be interpolated.
     my $argsStr = $params->{args} || "";
 
+    # Escape any escapes.
+    $str =~ s#\\#\\\\#g if ($escape);    # escape any escapes
+
     my @args = split( /\s*,\s*/, $argsStr );
 
     # fill omitted args with empty strings
@@ -47,6 +64,26 @@
     return $result;
 }
 
+sub _validate {
+
+    #my ( $contents, $number, $max, $min, $param_error ) = @_
+
+    $_[2] = $_[1] if ( $_[1] > $_[2] );    # Record maximum param number
+    $_[3] = $_[1] if ( $_[1] < $_[3] );    # Record minimum param number
+
+    if ( $_[1] > 100 ) {
+        $_[4] = 1;                         # Set error flag
+        return
+"<span class=\"foswikiAlert\">Excessive parameter number $_[2], MAKETEXT rejected.</span>";
+    }
+    if ( $_[1] < 1 ) {
+        $_[4] = 1;                         # Set error flag
+        return
+"<span class=\"foswikiAlert\">Invalid parameter <code>\"$_[0]\"</code>, MAKETEXT rejected.</span>";
+    }
+    return "[$_[0]]";    # Return the complete bracket parameter without escapes
+}
+
 1;
 __END__
 Foswiki - The Free and Open Source Wiki, http://foswiki.org/
 

Action Plan with Timeline

• 2012-12-05 - The Locale::Maketext vulnerability was discussed on the Perl5Porters email list, triggered review of Foswiki code.
• 2012-12-05 - Patched version (1.23) of Locale::Maketext is released.
• 2012-12-08 - The [_999999] DoS issue identified and sent to foswiki security list.
• 2012-12-09 - The "remote execution" vulnerability in Locale::Maketext was confirmed on Foswiki.
• 2012-12-09 - Requested the CVE from MITRE.
• 2012-12-09 - TWiki notified of the Vulnerability.
• 2012-12-10 - Developer fixes code (George Clark) and security team validates the fixes.
• 2012-12-10 - Extensions.PatchItem12285Contrib released for Foswiki 1.1.x
• 2012-12-10 - Security team creates advisory with hotfix. Announcement delayed for coordination with TWiki (George Clark)
• 2012-12-12 - Updated Debian packages released (Sven Dowideit)
• 2012-12-12 - Send alert to foswiki-announce and foswiki-discuss mailing lists ( )
• 2012-12-14 - Publish advisory in Support web and update all related topics ( )
• 2012-12-14 - Reference to public advisory on Download page and Known Issues ( )
• 2012-xx-xx - Release Manager builds patch release ( )
• 2012-xx-xx - Issue a public security advisory (vuln@secunia.com, cert@cert.org, bugs@securitytracker.com, full-disclosure@lists.netsys.com, vulnwatch@vulnwatch.org) ( )

• Set ALLOWTOPICCHANGE = SecurityGroup