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Foswiki Security Alert CVE-2012-6329, CVE-2012-6330 Remote code execution and other vulnerabilities in MAKETEXT macro
From: George Clark <geonwiki () fenachrone com>
Date: Fri, 14 Dec 2012 16:28:48 -0500

---+ Security Alert: Code injection vulnerability in MAKETEXT macro,
Denial of Service vulnerability in MAKETEXT macro.

This advisory alerts you of a potential security issue with your Foswiki
installation. A vulnerability has been reported against the core Perl
module CPAN:Locale::Maketext, which Foswiki uses to provide translations
when {UserInterfaceInternationalization} is enabled in the
configuration. Because of this vulnerability it may be possible for a
user to run arbitrary shell commands and code on the server through a
crafted %MAKETEXT% macro. If your wiki allows commenting by users
without first logging in, then it may be possible for such an anonymous
user to exploit this vulnerability.


---++ Severity Level

Severity 1 issue: The web server can be compromised
The severity level was assigned by the Foswiki
Community.SecurityTaskTeam as documented in Development.SecurityAlertProcess

---++ Vulnerable Software Versions

All released versions of Foswiki are vulnerable to these issues

 - Foswiki 1.0.0 - 1.0.10
 - Foswiki 1.1.0 - 1.1.6

---++ MITRE Name for this Vulnerability

The Common Vulnerabilities and Exposures project has assigned the name
CVE-2012-6329 to this vulnerability, see
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-6329
CVE-2012-6330 was assigned to the Denial of Service vulnerability, see
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-6330

---++ 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 will pass through strings to
Locale::Maketext where they are executed under the control of the CGI
user on the server.  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. (CVE-2012-6329)

A crafted %MAKETEXT{}% macro will consume large amounts of memory and
exhaust swap space.  (CVE-2012-6330)

---++ Impact

Arbitrary code execution on the server can expose the file system.

A second less severe Denial of Service vulnerability is also addressed
by this alert.

---++ Details

A crafted %MAKETEXT{}% macro can cause multiple issues:
   * Execute arbitrary code on the server by passing unsanitized strings
to Locale::Maketext.
   * 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.
   * 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
[[Extensions.PatchItem12285Contrib][http://foswiki.org/Extensions/PatchItem12285Contrib]]
to your Foswiki 1.1.x system (Does not apply to Foswiki 1.0.x) __or__
   * Disable {UserInerfaceInternationalization} in your  LocalSite.cfg
_(Does not protect against [[SecurityAlert-CVE-2012-6330]])_ __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

In addition,  CPAN:Locale::Maketext version 1.23 or newer should be
installed.

Upgrade to the latest patched production Download.FoswikiRelease01x01x07
once released

*The Foswiki patch fixes other issues with the %MAKETEXT% macro beyond
the code execution issue. Even if the new Locale::Maketext is installed,
it is strongly recommended to apply the Foswiki patch.*


---++ Hotfix for Foswiki Release 1.1.0 - 1.1.6

Install http://foswiki.org/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 CVE-2012-6329 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
Extensions.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

============ vvv CUT vvv =============
--- Foswiki.pm  2010-01-17 09:16:20.000000000 -0500
+++ Foswiki.pm  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} || "";

============ ---CUT--- =============


---++ Manual patch for Foswiki Release 1.1.0 -> 1.1.6

Installing the Extensions.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]]:

============ vvv CUT vvv =============
--- lib/Foswiki/Macros/MAKETEXT.pm   2012-12-11 10:51:12.959268829 -0500
+++ lib/Foswiki/Macros/MAKETEXT.pm   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/

============ ^^^ CUT ^^^ =============

---++ 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 cve-assign () mitre org 
   * 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) ( )


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