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a collection of tools to enumerate and attack self-hosted Skype for Business and Microsoft Lync installations

Note: these tools will not work with Skype/Lync installations hosted at Microsoft.


DerbyCon 6.0 YouTube link: https://www.youtube.com/watch?v=v0NTaCFk6VI

DerbyCon 6.0 Slide Deck: https://github.com/nyxgeek/nyxgeek-slides/blob/master/TheWeakestLync.pdf

scripts

  • lyncsmash.py - enumerate users via auth timing bug while brute forcing, lock accounts, locate lync installs
  • find_domain.sh - example of how to use Nmap with http-ntlm-info script to discover internal NetBIOS & domain names
  • brute_force_ntlm.sh - example of a brute force attack against Skype/Lync using Medusa
  • ntlm-info.py - script to get NetBIOS Domain name from NTLM auth

wordlists

  • skype-directories.txt - a listing of directories that may have NTLM-auth enabled
  • alexa-top-20000-sites.txt - a listing of the top 20,000 Alexa sites - to be used with discover mode

If you're looking for username lists, I highly recommend 'Statistically Likely Usernames': https://github.com/insidetrust/statistically-likely-usernames.git


using lyncsmash.py

lyncsmash has three operating modes:

  • enum - use to enumerate users via the auth timing attack
  • discover - will take a list of domains and determine which use Skype for Business/Lync
  • lock - make repeated bad authentication attempts in order to lock out an account

lyncsmash.py enum - enumerate users

** WARNING: THIS PERFORMS A DOMAIN LOGIN ATTEMPT AND CAN LOCK OUT ACCOUNTS **

Parameters:
    -H	hostname
    -U	username list
    -p  password
    -P  password list
    -d	NetBIOS domain
    -o  output file
    -t  manually set timeout
    -r  Randomize the user input list

In this mode lyncsmash will enumerate usernames via a timing attack, using the Webticket service located on the Lync Front-End server. If a bad username and/or domain is specified, the response will be long. If it is a valid user, the response will be short. Due to limitations of the timing-attack, this can only be run single-threaded.

usage:

python lyncsmash.py enum -H 2013-lync-fe.contoso.com -U usernamelist.txt -P passwordlist.txt -d CONTOSO -o CONTOSO_output.txt

or

python lyncsmash.py enum -H 2013-lync-fe.contoso.com -U usernamelist.txt -p Winter2017 -d CONTOSO

lyncsmash.py discover - discovering domains that are running Skype/Lync

Parameters:
    -H	host list - one DNS base domain per line

In this mode lyncsmash will attempt to enumerate various Skype/Lync subdomains via DNS, and returns a score based on number of indicators. Wildcard domains are discarded.

usage:

python lyncsmash.py discover -H domain_list.txt

lyncsmash lock - lockout an account with repeated login failures

** WARNING: THIS WILL LOCK OUT ACCOUNTS. **

Parameters:
    -H	hostname
    -u	username to lock out
    -d	NetBIOS domain

In this mode lyncsmash will make 5 login attempts with an incorrect password, attempting to lock out a user account.

usage:

python lyncsmash.py lock -H 2013-lync-fe.contoso.com -u administrator -d CONTOSO


ntlm-info.py

This script examines the HTTP headers from a null NTLM auth attempt. It will test against the /abs/ directory by default but any directory can be specified as a second argument (see below). This is a remake of the http-ntlm-info script from nmap (https://nmap.org/nsedoc/scripts/http-ntlm-info.html).

Additional potential NTLM auth directories can be found in this repository under wordlists (https://github.com/nyxgeek/lyncsmash/blob/master/wordlists/skype-directories.txt).

If you're having trouble locating NTLM auth directories, I wrote a script to scan for them: (https://github.com/nyxgeek/ntlmscan).

Requires requests_ntlm -- install with:

pip install requests_ntlm

Usage:

python ntlm-info.py dialin.domain.com

python ntlm-info.py dialin.domain.com RequestHandlerExt

thanks!

Thanks to @coldfusion39, @spoonman1091, @nettitude, @shellfail, picarddam, @fals3s3t, and @Oddvarmoe for contributing fixes and improvements!