############################################################# # # COMPASS SECURITY ADVISORY # http://www.csnc.ch/en/downloads/advisories.html # ############################################################# # # 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 # ############################################################# 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/