The STRIDE Framework

STRIDE is a threat categorization framework developed at Microsoft. It gives you six categories of threats so you can systematically ask 'what could go wrong?' for each component of a system.

STRIDE is a mnemonic for the six threat types:

• Spoofing
• Tampering
• Repudiation
• Information disclosure
• Denial of service
• Elevation of privilege

Each STRIDE category is the violation of a desirable security property. This pairing helps you remember what each threat attacks:

Spoofing is pretending to be someone or something you are not. It violates authentication.

Examples:

• Logging in with stolen credentials
• Forging the 'From' address of an email
• Setting up a fake login page to harvest passwords
• Impersonating a trusted server

Typical mitigations: strong authentication, multi-factor authentication, mutual TLS, and digital signatures.

Tampering is unauthorized modification of data or code. It violates integrity.

Examples:

• Altering a price field in an HTTP request before submission
• Modifying a database record without authorization
• Injecting malicious code into a software update
• Changing a log file to hide activity

Mitigations: input validation, integrity checks (hashes/HMAC), code signing, and access controls.

Repudiation is a user denying they performed an action, when the system cannot prove otherwise. It violates non-repudiation.

Example: a user makes a fraudulent transaction, then claims they never did it, and there are no logs to prove it.

Mitigations:

• Comprehensive, tamper-resistant audit logging
• Digital signatures on critical actions
• Secure timestamps and log forwarding to a write-once store

Information disclosure is exposing data to people who should not see it. It violates confidentiality.

Examples:

• An unencrypted database leaking customer records
• Verbose error messages revealing stack traces or queries
• A misconfigured cloud bucket exposed to the public
• Sensitive data sent over plaintext HTTP

Mitigations: encryption in transit and at rest, least-privilege access, and careful error handling.

Denial of service (DoS) is making a system unavailable to legitimate users. It violates availability.

Examples:

• Flooding a server with traffic (DDoS)
• A single expensive query exhausting database resources
• Filling up disk space with uploads
• Triggering an infinite loop or resource leak

Mitigations: rate limiting, quotas, input size limits, autoscaling, and upstream DDoS protection.

Elevation of privilege is gaining capabilities beyond what you are authorized to have. It violates authorization.

Examples:

• A normal user accessing an admin endpoint
• Exploiting a bug to run code as root
• Changing your own role via a manipulated parameter
• Escaping a container to reach the host

Mitigations: enforce authorization on every request, principle of least privilege, and sandboxing.

The power of STRIDE comes from applying it methodically. For each element in your design diagram, walk through all six categories and ask if that threat applies.

There are two ways to apply STRIDE:

• STRIDE-per-element — analyze each component (process, data store, external entity) against relevant threat types
• STRIDE-per-interaction — analyze each data flow between elements

Not every threat applies to every element. For example, data stores rarely 'spoof,' but they are prime targets for tampering and information disclosure. Use the relevant subset for each element.

STRIDE pairs naturally with a mitigation strategy. For each identified threat you choose one of four responses:

• Mitigate — add a control to reduce the risk
• Eliminate — remove the feature or component causing it
• Transfer — shift the risk (insurance, third party)
• Accept — knowingly tolerate a low risk

Document the decision for every threat so nothing is silently ignored.

Test your knowledge of STRIDE categories.

You learned the STRIDE framework:

• Spoofing (authentication), Tampering (integrity), Repudiation (non-repudiation)
• Information disclosure (confidentiality), Denial of service (availability), Elevation of privilege (authorization)
• Each category violates a specific security property
• Apply STRIDE methodically per element or per interaction
• For each threat, decide to mitigate, eliminate, transfer, or accept

Next, you will map data flows and trust boundaries to know where to apply STRIDE.