Attack Ent T1566 002 Spearphishing Link

MITRE ATT&CK T1566.002: Spearphishing Link

When to use this skill

Use this skill when the task involves T1566.002, Spearphishing Link, 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: T1566.002
• Technique name: Spearphishing Link
• Type: sub-technique
• ATT&CK URL: https://attack.mitre.org/techniques/T1566/002
• Tactics: initial-access
• Platforms: Identity Provider, Linux, macOS, Office Suite, SaaS, Windows
• Required permissions: Not specified
• Effective permissions: Not specified
• Defenses bypassed: Not specified

ATT&CK description

Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place.

Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly. Additionally, adversaries may use seemingly benign links that abuse special characters to mimic legitimate websites (known as an "IDN homograph attack").(Citation: CISA IDN ST05-016) URLs may also be obfuscated by taking advantage of quirks in the URL schema, such as the acceptance of integer- or hexadecimal-based hostname formats and the automatic discarding of text before an “@” symbol: for example, hxxp://google.com@1157586937.(Citation: Mandiant URL Obfuscation 2023)

Adversaries may also utilize links to perform consent phishing/spearphishing campaigns to Steal Application Access Tokens that grant immediate access to the victim environment. For example, a user may be lured into granting adversaries permissions/access via a malicious OAuth 2.0 request URL that when accepted by the user provide permissions/access for malicious applications.(Citation: Trend Micro Pawn Storm OAuth 2017)(Citation: Microsoft OAuth 2.0 Consent Phishing 2021) These stolen access tokens allow the adversary to perform various actions on behalf of the user via API calls.(Citation: Microsoft OAuth 2.0 Consent Phishing 2021)

Similarly, malicious links may also target device-based authorization, such as OAuth 2.0 device authorization grant flow which is typically used to authenticate devices without UIs/browsers. Known as “device code phishing,” an adversary may send a link that directs the victim to a malicious authorization page where the user is tricked into entering a code/credentials that produces a device token.(Citation: SecureWorks Device Code Phishing 2021)(Citation: Netskope Device Code Phishing 2021)(Citation: Optiv Device Code Phishing 2021)

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

• Audit
• Restrict Web-Based Content
• Software Configuration
• User Account Management
• User Training

Known threat context

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

• AADInternals (tool)
• APT-C-36 (intrusion-set)
• APT1 (intrusion-set)
• APT29 (intrusion-set)
• APT3 (intrusion-set)
• APT32 (intrusion-set)
• APT33 (intrusion-set)
• APT39 (intrusion-set)
• APT42 (intrusion-set)
• AppleJeus (malware)
• Bazar (malware)
• BlackTech (intrusion-set)
• Bumblebee (malware)
• C0011 (campaign)
• C0021 (campaign)
• Cobalt Group (intrusion-set)
• Confucius (intrusion-set)
• DarkGate (malware)
• EXOTIC LILY (intrusion-set)
• Earth Lusca (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

• Philip Winther
• Shailesh Tiwary (Indian Army)
• Mark Wee
• Jeff Sakowicz, Microsoft Identity Developer Platform Services (IDPM Services)
• Saisha Agrawal, Microsoft Threat Intelligent Center (MSTIC)
• Kobi Haimovich, CardinalOps
• Menachem Goldstein