Soreco AG Xpert.Line 3.0 Authentication Bypass

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#  
  
# COMPASS SECURITY ADVISORY  
  
# http://www.csnc.ch/en/downloads/advisories.html  
  
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# Product: Xpert.Line  
  
# Vendor: Soreco AG [1]  
  
# CVE ID: CVE-2015-3442  
  
# Subject: Authentication Bypass  
  
# Risk: Critical  
  
# Effect: Remotely exploitable  
  
# Author: Alessandro Zala ([email protected])  
  
# Andreas Hunkeler ([email protected])  
  
# Date: 06.03.2015  
  
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Introduction:  
  
-------------  
  
The Xpert.Line software [2] is a Human Resources Management solution that  
helps  
  
companies administrating information assets of their employees. It manages  
  
all the private information about the employees. Compass Security [3] found  
a  
  
vulnerability that allows an attacker to impersonate other users by only  
  
knowing the username of the person. With this flaw a user can bypass the  
  
authentication mechanism and achieve highest privileges to access personal  
  
information like the salary of any employee or manipulate security settings  
  
(e.g. accounts) of the application.  
  
  
  
Affected:  
  
---------  
  
Xpert.Line Version 3.0 (Xpert.Center). Other versions have not been tested.  
  
  
  
Vulnerability Description:  
  
--------------------------  
  
Xpert.Line has several authentication mechanisms to authenticate the user to  
the  
  
application. One of the authentication mechanisms relies only on client-side  
  
functionalities. When the Xpert.Line Windows client is started, it first  
  
retrieves the username of the current logged-in Windows user by using an API  
  
call to "getUserNameA" from the Windows built-in library "advapi32.dll".  
This  
  
information is then sent to the server to authenticate the user to  
Xpert.Line  
  
and it is also used for all subsequent requests to the server.  
  
  
  
Impact:  
  
-------  
  
A malicious user can impersonate any user by intercepting the above  
mentioned  
  
API call to "getUserNameA" in "advapi32.dll" and change the value returned  
to  
  
an arbitrary name. This allows impersonating higher privileged users to  
access  
  
sensitive information like salary information or to create new administrator  
  
accounts.  
  
  
  
Workaround / Fix:  
  
-----------------  
  
The affected authentication mechanism can be deactivated. The vendor  
currently  
  
is not willing to remove this authentication mechanism. Instead, vendor  
offers  
  
more secure authentication mechanisms and considers this a configuration  
issue.  
  
  
  
To deactivate the affected unsecure authentication method do the following:  
  
1. Go to Xpert.Security  
  
2. Got to "change environment" settings  
  
3. Change the authentication type to a secure setting (e.g. LDAPs)  
  
  
  
Source: Xpert.Security LDAP documentation, received from vendor on  
06.03.2015  
  
  
  
Timeline:  
  
---------  
  
29.01.2015: Vulnerability detected  
  
19.02.2015: Initial contact, conference call with vendor  
  
03.03.2015: CVE ID requested  
  
03.03.2015: Request vendor's security contact information ([email protected])  
  
05.03.2015: 2nd Request vendor's security contact information  
([email protected])  
  
05.03.2015: Vendor notification with technical details to contact person via  
  
  
secured channel  
  
05.03.2015: Conference call with vendor discussing finding and next steps  
  
06.03.2015: 2nd conference call with vendor to discuss workaround and   
  
publication, vendor approved immediate publication  
  
29.04.2015: CVE ID received: CVE-2015-3442  
  
02.07.2015: Public disclosure  
  
  
  
Very positive was the handling of the notification. The vendor was very  
  
responsive to our notification and was very willing to cooperate with us.  
  
  
  
References:  
  
-----------  
  
[1] http://www.sorecoweb.ch/home/  
  
[2] http://www.xpertline.ch/  
  
[3] http://www.csnc.ch/en/  
  
  
  
  
  
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