Reconnaissance — MITRE ATT&CK® Tactic TA0043

Tactical objective

Adversaries collect information about people, organizations, technology, and exposed services before or during an operation so they can choose targets and shape later actions.

In ATT&CK, a tactic describes why an adversary performs an action. Reconnaissance is not necessarily a single chronological phase, and techniques associated with it can appear repeatedly or alongside other objectives during one operation.

This BMC path highlights 3 high-value profiles: Active Scanning (T1595), Gather Victim Identity Information (T1589), Search Open Websites and Domains (T1593). The complete ATT&CK catalog contains additional techniques and sub-techniques, so this page is a teaching sequence rather than an exhaustive replacement for the official matrix.

What defenders should ask

The best tactical questions connect observable behavior to an asset, identity, trust decision, and consequence. They help investigators test competing explanations instead of inferring intent solely from an alert label.

• What information is publicly exposed?
• Which observations indicate deliberate targeting rather than ordinary internet noise?
• Can repeated probes, identity research, and infrastructure research be correlated across time?
• Which part of the environment is outside current telemetry or control scope?
• What earlier and later behaviors would strengthen or weaken this hypothesis?

Architecture and preventive controls

Prevention of reconnaissance behavior rarely depends on one product. Architecture, identity, configuration, network paths, software maintenance, user workflow, and recovery design all influence the available opportunities.

Control design should identify where the organization can deny, constrain, slow, or expose the behavior. For every control, define the expected evidence, exception process, failure mode, and owner.

• Reduce unnecessary public exposure and stale records.
• Monitor external attack surfaces, certificate transparency, and brand abuse.
• Use rate controls and protective services for exposed applications.
• Train personnel to recognize pretext development and suspicious outreach.

Detection and evidence

Detection for reconnaissance should focus on behavior and context rather than an identifier alone. The same command, protocol, or configuration action may be authorized or malicious depending on the actor, asset, sequence, and expected workflow.

Use multiple evidence sources when possible. Independent identity, endpoint, network, cloud, and application records are especially valuable when an adversary can alter host-local evidence.

• Web and API gateway request patterns
• DNS and certificate-transparency observations
• External attack-surface inventory changes
• Email and social-engineering reports
• Asset criticality, identity role, and change-window context
• Correlated preceding and follow-on behaviors across tactics

Investigation and response

Build a timeline that separates observed actions from inferred objectives. Preserve the event, process, account, resource, destination, and configuration evidence supporting every mapping.

Response priorities for reconnaissance should address the active behavior while also identifying the access and dependencies that made it possible. Containment that removes one symptom but leaves the enabling identity, trust path, or persistence mechanism can create a false sense of closure.

• Confirm the affected scope and earliest supported activity.
• Identify accounts, hosts, workloads, applications, and external infrastructure involved.
• Preserve volatile and centralized evidence before making disruptive changes.
• Contain the enabling path and validate that controls are functioning.
• Search for related techniques and repeat activity across the environment.
• Document confidence, residual risk, and the conditions for recovery.

Safe tabletop exercise

Create a fictional scenario in which an adversary pursues the Reconnaissance objective against a representative business service. Select two techniques from this path and identify the architecture, identity, and evidence required for the behavior.

Have one participant act as the investigator and another as the service owner. Compare what security tooling reports with what the service owner knows about expected behavior. Record one prevention gap, one detection gap, and one recovery or resilience improvement.

• State the assumed adversary access and objective.
• Define the affected platform and business service.
• List expected benign activity that could resemble the behavior.
• Identify the minimum evidence needed to reach a defensible conclusion.
• Map only what the scenario actually supports.

Attribution and scope

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MITRE ATT&CK® and ATT&CK® are registered trademarks of The MITRE Corporation. Bare Metal Cyber is not affiliated with or endorsed by MITRE.

This article is an original Bare Metal Cyber educational treatment of tactic TA0043 reviewed against Enterprise ATT&CK v19.2. Verify current technique relationships and object status on the official tactic page.

Certification relevance

This subject appears in or supports the following certification bodies of knowledge:

Authoritative sources

• MITRE ATT&CK® Reconnaissance Tactic
• MITRE ATT&CK® Data & Tools
• MITRE ATT&CK® Legal and Branding Guidance