LLMNR/NBT-NS Poisoning

Quick Example

Let's walk through a quick example of the attack flow at a very high level:

  1. A host attempts to connect to the print server at \\print01.inlanefreight.local, but accidentally types in \\printer01.inlanefreight.local.

  2. The DNS server responds, stating that this host is unknown.

  3. The host then broadcasts out to the entire local network asking if anyone knows the location of \\printer01.inlanefreight.local.

  4. The attacker (us with Responder running) responds to the host stating that it is the \\printer01.inlanefreight.local that the host is looking for.

  5. The host believes this reply and sends an authentication request to the attacker with a username and NTLMv2 password hash.

  6. This hash can then be cracked offline or used in an SMB Relay attack if the right conditions exist.

Tools

Tool

Description

Responder is a purpose-built tool to poison LLMNR, NBT-NS, and MDNS, with many different functions.

Inveigh is a cross-platform MITM platform that can be used for spoofing and poisoning attacks.

Metasploit has several built-in scanners and spoofing modules made to deal with poisoning attacks.

  • Both responder and inveigh can attack the following protocols: LLMNR, DNS, MDNS, NBNS, DHCP, ICMP, HTTP, HTTPS, SMB, LDAP, WebDAV, Proxy Auth

  • But responder also has support for:

    • MSSQL

    • DCE-RPC

    • FTP, POP3, IMAP, and SMTP auth

Sample Exploitation

Linux

  1. Start Responder

  2. Cracking NTLMv2 hash with hashcat

  3. We now have the plaintext password of the user

Windows

  1. Start Inveigh

  2. Retrieve the Hash and crack it using hashcat as same as the method in linux

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