---
name: attack-ent-t1557-001-name-resolution-poisoning-and-smb-re
description: "Analyze MITRE ATT&CK T1557.001 Name Resolution Poisoning and SMB Relay in the enterprise matrix. Use for TTP triage, detection engineering, hunting, defensive emulation planning, mitigations, incident response mapping, ATT&CK coverage, or questions mentioning T1557.001, Name Resolution Poisoning and SMB Relay, or enterprise ATT&CK. By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.(Citation: BlackCat ransomware) This activ…"
license: MITRE ATT&CK Terms of Use apply to ATT&CK-derived content. See https://attack.mitre.org/resources/terms-of-use/
metadata:
  source: mitre-attack/attack-stix-data
  domain: enterprise
  attack_id: T1557.001
  attack_stix_id: attack-pattern--650c784b-7504-4df7-ab2c-4ea882384d1e
  attack_version: "2.0"
  attack_modified: "2026-02-03T16:53:09.295Z"
---

# MITRE ATT&CK T1557.001: Name Resolution Poisoning and SMB Relay

## When to use this skill

Use this skill when the task involves T1557.001, Name Resolution Poisoning and SMB Relay, enterprise ATT&CK, TTP mapping, detection engineering, hunting, incident-response enrichment, control validation, or authorized adversary-emulation planning. Treat it as a defensive analysis aid: keep outputs focused on understanding, detecting, mitigating, and safely validating this ATT&CK sub-technique.

## Technique context

- ATT&CK domain: enterprise
- ATT&CK ID: T1557.001
- Technique name: Name Resolution Poisoning and SMB Relay
- Type: sub-technique
- ATT&CK URL: https://attack.mitre.org/techniques/T1557/001
- Tactics: collection, credential-access
- Platforms: Windows
- Required permissions: Not specified
- Effective permissions: Not specified
- Defenses bypassed: Not specified

## ATT&CK description

By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.(Citation: BlackCat ransomware) This activity may be used to collect or relay authentication materials. 

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.(Citation: Wikipedia LLMNR)(Citation: TechNet NetBIOS)

Multicast Domain Name System(mDNS) is a zero-configuration service used to resolve hostnames to IP addresses with “.local” as a top-level domain. MDNS is based upon Domain Name System (DNS) format and allows hosts on the same network segment to perform name resolution for other hosts, using multicast.(Citation: mDNS RFC)

Adversaries can spoof an authoritative source for name resolution on a victim network by responding to LLMNR (UDP 5355)/NBT-NS (UDP 137)/mDNS (UDP 5353) 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](https://attack.mitre.org/techniques/T1040) and crack the hashes offline through [Brute Force](https://attack.mitre.org/techniques/T1110) 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 NTLMv1/v2 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.(Citation: byt3bl33d3r NTLM Relaying)(Citation: Secure Ideas SMB Relay) Additionally, adversaries may encapsulate the NTLMv1/v2 hashes into various other protocols, such as LDAP, MSSQL and HTTP, to expand and use multiple services with the valid NTLM response. 

Several tools may be used to poison name services within local networks such as NBNSpoof, Metasploit, and [Responder](https://attack.mitre.org/software/S0174).(Citation: GitHub NBNSpoof)(Citation: Rapid7 LLMNR Spoofer)(Citation: GitHub Responder)

## Agent workflow

1. Clarify scope: identify the system, asset class, log sources, cloud or endpoint platform, and whether the user wants triage, detection, coverage assessment, or safe emulation planning.
2. Load bundled resources as needed: use `references/technique-profile.json` for structured metadata, `references/detection-and-mitigation.md` for triage and telemetry guidance, `references/known-threat-context.md` for ATT&CK relationship context, and `templates/` for repeatable outputs.
3. Map observations to ATT&CK: compare the user's evidence to the ATT&CK description, tactics, platforms, and known procedure patterns before asserting a match.
4. Produce defensive outputs: prioritize hypotheses, telemetry requirements, detection logic ideas, validation steps, containment guidance, and mitigations.
5. Preserve uncertainty: distinguish confirmed evidence, plausible indicators, assumptions, and gaps. Recommend what to collect next.
6. Stay safe: do not provide malware, credential theft, persistence, evasion, destructive automation, or unauthorized exploitation instructions. For adversary emulation, keep steps bounded to approved lab or control-validation contexts and omit operational abuse details.

## Bundled resources

- `references/technique-profile.json`: machine-readable ATT&CK metadata for this technique.
- `references/detection-and-mitigation.md`: detection notes, telemetry checklist, triage questions, mitigation candidates, and false-positive considerations.
- `references/known-threat-context.md`: ATT&CK relationship context with attribution cautions.
- `templates/detection-brief.md`: detection engineering brief template.
- `templates/hunt-plan.md`: threat hunt plan template.
- `templates/incident-response-note.md`: incident response note template.
- `templates/coverage-assessment.md`: ATT&CK coverage assessment template.
- `scripts/render_brief.py`: local helper that renders a Markdown defensive brief from `technique-profile.json`.
- `assets/output-schema.json`: JSON schema for structured technique analysis outputs.

To generate a quick brief, run `python scripts/render_brief.py --output brief.md` from inside this skill directory, or adapt the templates directly.

## Detection guidance

No ATT&CK detection guidance was present in the source STIX object.

## Useful telemetry and data sources

- Not specified in the STIX object.

## Mitigations to consider

- Disable or Remove Feature or Program
- Filter Network Traffic
- Network Intrusion Prevention
- Network Segmentation

## Known threat context

Use these examples only as contextual leads, not as proof that an observed event is this technique:

- Empire (tool)
- Impacket (tool)
- Lazarus Group (intrusion-set)
- PoshC2 (tool)
- Pupy (tool)
- Responder (tool)
- Wizard Spider (intrusion-set)

## Recommended output pattern

When responding with this skill, structure the answer as:

- Assessment: whether the evidence supports this ATT&CK mapping and why.
- Evidence: specific indicators, logs, behaviors, and assumptions.
- Detection: telemetry sources, analytic logic, and tuning considerations.
- Response: containment, eradication, recovery, and validation actions.
- Coverage gaps: missing logs, sensors, controls, or environmental details.
- References: include the ATT&CK URL and any user-provided evidence references.

## ATT&CK contributors

- Eric Kuehn, Secure Ideas
- Matthew Demaske, Adaptforward
- Andrew Allen, @whitehat_zero
- Arad Inbar