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MITRE ATT&CK® Technique

T1171: LLMNR/NBT-NS Poisoning and Relay

Link-Local Multicast Name Resolution (LLMNR) and NetBIOS Name Service (NBT-NS) are Microsoft Windows components that serve as alternate methods of host identification. LLMNR is based upon the Domain Name System (DNS) format and allows hosts on the same local link to perform name resolution for other hosts. NBT-NS identifies systems on a local network by their NetBIOS name. [1] [2]

Adversaries can spoof an authoritative source for name resolution on a victim network by responding to LLMNR (UDP 5355)/NBT-NS (UDP 137) traffic as if they know the identity of the requested host, effectively poisoning the service so that the victims will communicate with the adversary controlled system. If the requested host belongs to a resource that requires identification/authentication, the username and NTLMv2 hash will then be sent to the adversary controlled system. The adversary can then collect the hash information sent over the wire through tools that monitor the ports for traffic or through Network Sniffing and crack the hashes offline through Brute Force to obtain the plaintext passwords. In some cases where an adversary has access to a system that is in the authentication path between systems or when automated scans that use credentials attempt to authenticate to an adversary controlled system, the NTLMv2 hashes can be intercepted and relayed to access and execute code against a target system. The relay step can happen in conjunction with poisoning but may also be independent of it. [3][4]

Several tools exist that can be used to poison name services within local networks such as NBNSpoof, Metasploit, and Responder. [5] [6] [7]

EnterpriseT1171TechniqueObject v2.1 Modified
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Historical object

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Official MITRE ATT&CK definition

LLMNR/NBT-NS Poisoning and Relay

Link-Local Multicast Name Resolution (LLMNR) and NetBIOS Name Service (NBT-NS) are Microsoft Windows components that serve as alternate methods of host identification. LLMNR is based upon the Domain Name System (DNS) format and allows hosts on the same local link to perform name resolution for other hosts. NBT-NS identifies systems on a local network by their NetBIOS name. [1] [2]

Adversaries can spoof an authoritative source for name resolution on a victim network by responding to LLMNR (UDP 5355)/NBT-NS (UDP 137) traffic as if they know the identity of the requested host, effectively poisoning the service so that the victims will communicate with the adversary controlled system. If the requested host belongs to a resource that requires identification/authentication, the username and NTLMv2 hash will then be sent to the adversary controlled system. The adversary can then collect the hash information sent over the wire through tools that monitor the ports for traffic or through Network Sniffing and crack the hashes offline through Brute Force to obtain the plaintext passwords. In some cases where an adversary has access to a system that is in the authentication path between systems or when automated scans that use credentials attempt to authenticate to an adversary controlled system, the NTLMv2 hashes can be intercepted and relayed to access and execute code against a target system. The relay step can happen in conjunction with poisoning but may also be independent of it. [3][4]

Several tools exist that can be used to poison name services within local networks such as NBNSpoof, Metasploit, and Responder. [5] [6] [7]

View the same entry on attack.mitre.org (MITRE-hosted reference; in-page links above use the Glexia ATT&CK library.)

Glexia analysis

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ATT&CK relationship table

Related techniques

This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.

1 rows
Domain ID Name Relationship / procedure
Enterprise T1557.001 Name Resolution Poisoning and SMB Relay Sub-technique This object revoked by Name Resolution Poisoning and SMB Relay.
Relationship explorer

All related ATT&CK context

revoked by · Technique T1557.001: Name Resolution Poisoning and SMB Relay Enterprise
Change history

Object version and sync metadata

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ATT&CK release
19.1
Object version
2.1
Created
Modified
Raw hash
736243ec874bd54f...
Imported snapshots across ATT&CK releases (1)
Release Bundle imported Object version Modified Status Raw hash
19.1 2.1 Current bundle Revoked 736243ec874b…
Raw source

Mirrored ATT&CK source object

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Source references

External references and citations

MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.

  1. [1]
    Wikipedia LLMNR

    Wikipedia. (2016, July 7). Link-Local Multicast Name Resolution. Retrieved November 17, 2017.

    Open source URL
  2. [2]
    TechNet NetBIOS

    Microsoft. (n.d.). NetBIOS Name Resolution. Retrieved November 17, 2017.

    Open source URL
  3. [3]
    byt3bl33d3r NTLM Relaying

    Salvati, M. (2017, June 2). Practical guide to NTLM Relaying in 2017 (A.K.A getting a foothold in under 5 minutes). Retrieved February 7, 2019.

    Open source URL
  4. [4]
    Secure Ideas SMB Relay

    Kuehn, E. (2018, April 11). Ever Run a Relay? Why SMB Relays Should Be On Your Mind. Retrieved February 7, 2019.

    Open source URL
  5. [5]
    GitHub NBNSpoof

    Nomex. (2014, February 7). NBNSpoof. Retrieved November 17, 2017.

    Open source URL
  6. [6]
    Rapid7 LLMNR Spoofer

    Francois, R. (n.d.). LLMNR Spoofer. Retrieved November 17, 2017.

    Open source URL
  7. [7]
    GitHub Responder

    Gaffie, L. (2016, August 25). Responder. Retrieved November 17, 2017.

    Open source URL
  8. [8]
    GitHub Conveigh

    Robertson, K. (2016, August 28). Conveigh. Retrieved November 17, 2017.

    Open source URL
  9. [9]
    Sternsecurity LLMNR-NBTNS

    Sternstein, J. (2013, November). Local Network Attacks: LLMNR and NBT-NS Poisoning. Retrieved November 17, 2017.

    Open source URL
  10. [10]
    mitre-attack T1171
    Open source URL
Source and licensing

Source: MITRE ATT&CK®. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. MITRE ATT&CK and ATT&CK are registered trademarks of The MITRE Corporation. Glexia is not affiliated with or endorsed by MITRE.

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