Initial Access is the MITRE ATT&CK tactic that describes how an adversary first gains a foothold in an environment. It is a category of techniques, not one specific attack method. Initial access may involve phishing, exploitation of a public-facing application, valid accounts, drive-by compromise, external remote services, supply-chain compromise, or other entry paths.
Why the Term Matters
In Data Breach & Incident Response, identifying initial access helps explain how the incident began and what controls failed or were bypassed. It can guide containment, credential resets, vulnerability remediation, notification scope, and threat-hunting priorities. It also helps separate the entry event from later activity such as discovery, lateral movement, privilege escalation, persistence, or exfiltration.
The entry point is sometimes obvious, such as a confirmed phishing email followed by a successful sign-in from suspicious infrastructure. In other cases, initial access is inferred from multiple weak signals. A missing log window, older compromise, or reused credentials can make the first event difficult to establish.
Evidence Sources
- Email headers, attachments, URLs, delivery logs, and user click or report data.
- Authentication records from Microsoft Entra ID, VPNs, remote desktop, SaaS services, and identity providers.
- Web-server logs, application logs, WAF events, and vulnerability evidence for public-facing systems.
- Endpoint telemetry showing process execution, malware staging, browser activity, or remote access tools.
- Cloud audit logs showing app consent, token activity, new credentials, or administrative changes.
Initial Access Is Not the Whole Incident
Initial access explains entry, but it does not establish impact. An attacker may gain access and do little, or may move quickly toward command and control, data staging, credential access, or data breach conditions. Investigators should avoid treating entry as proof of data access or data loss without supporting evidence.
Common Misconceptions
- Initial Access is not synonymous with phishing, though phishing is a common technique.
- A valid login can still be adversary initial access when credentials or tokens were misused.
- Remediation should address the specific entry path and any downstream control gaps.