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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 (alessandro.zala@csnc.ch)

#            Andreas Hunkeler (andreas.hunkeler@csnc.ch)

# 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 (info@soreco.ch)

05.03.2015: 2nd Request vendor's security contact information
(info@soreco.ch)

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/