Owning Windows Networks with Responder 1.7

A lot has beenhappening with Responder lately!

Everything is stillwritten in pure python for portability's sake, there's no need toinstall any third-party libraries.

For starters, Responderis a passive credentials gathering tool.

It listens for specificNBT-NS (NetBIOS Name Service) and LLMNR (Link-local Multicast NameResolution) queries and poisons the issuer. Responder has severalrogue authentication servers listening on several UDP and TCP ports.If you want more information on LLMNR &NBT-NS poisoning, read myprevious blog post:http://blog.spiderlabs.com/2012/10/introducing-responder-10.html

New Functionalitiesin Responder:

- Rogue SMB server nowmakes use of SMB Extended Security NTLMSSP authentication (NTLMv1/v2)by default, so you won't miss a hash!

- Rogue FTP serverclear text credential capture module (enabled by default).

- Small DNS server(enabled by default).

- ICMP Redirectsutility for Windows =< 5.2 Domain members.

- Stealth mode DomainController finder (enabled by default).

- Host Fingerprintmodule (need to specify -f On).

- All activity is nowlogged into a file named Responder-Session.log with date and time foreach entry.

- Ability to switchOn/Off any rogue server via command line.

- Ability to specify adifferent challenge for all NTLM rogue servers.

- NT4 specific SMBclear text credentials support.

Responder 1.7 inaction:

ICMP Redirect forWindows =< 5.2 Domain members:

Windows =< 5.2 Domainmembers (XP, Windows server 2003 and above) have ICMP Redirectenabled by default. This functionality can be used to remotely add(with no authentication required) a new route for a given host. Yes,you heard me right.

Case scenario example:

  • Attacker has IP address

  • Domain controller has IP address, which is also the primary DNS server.

  • Victim workstation has IP address

  • Gateway has IP address

Thisscreenshot reflects the victim default route prior using ResponderICMP Redirect utility:


So we start bydisabling outgoing ICMP requests:


We launch ResponderIcmp-Redirect.py utility accordingly:


Back to XP domainmember route configuration:


Now we can create a NATfirewall rule and answer all DNS queries for from192.168.2.39 by issuing this command as root :

iptables -t nat-A PREROUTING -p udp --dst --dport 53 -j DNAT--to-destination

Fromthere, Responder will reply to DNS requests and make use of its rogueauthentication servers:


StealthDomain Controller Finder:

Responderhas a Browser listener (UDP 138) and waits for Domain Master Browser(DMB) Announcements. In aWindows NT domain context, only the Primary Domain Controller can bethe DMB according to Microsoft documentation. If there'sno domain set and workstations are in a Workgroup, usually the LocalMaster Browser (LMB) will be the DMB.

In thisexample, Responder is simply listening on port UDP 138:


OSfingerprint module:

Whenenabled, the fingerprint module will fingerprint any host who issuedeither an LLMNR or NBT-NS query :


FTPcredential module:

Thismodule will grab plaintext FTP credentials:



Apart fromthe fact that with its internal components Responder is a great toolto gather encrypted or clear text credentials passively, it can alsobe combined with ARP spoofing attacks in order to amplify itsresults.

As always, latest version is available here : https://github.com/SpiderLabs/Responder

Trustwave reserves the right to review all comments in the discussion below. Please note that for security and other reasons, we may not approve comments containing links.