Definition
Application code which prevents its own subroutines from accessing intra-process / internal memory space.
How it works
Some applications implement logic to permit or deny a particular subroutine access to other data within the same application process. This is intended to prevent critical application process data from being tampered with.
Application-based Process Isolation in web browsers.
Isolation in browsers usually is designed with the following architectural mindset:
The following aspects help make browser-based process isolation possible:
- Sandboxes and web resources should not be allowed to access each other because compromise of one should not effect the other.
- The principle of least-privilege should be followed when browsing.
- Same Origin Policy
- Separate tabs and iframes use their own DOMs (cross-site document object models always run as a different process)
- CORS ensures cross-site data is not delivered to a process unless the server allows it
- Cookie and local data storage is separated by domain/site
- Separate execution environments (threads)
Considerations
- Using isolation in browsers does mitigate and protect by default some types of attacks (e.g. renderer attacks and access to the filesystem) but it depends on correct configuration of CORS, use of valid/appropriate certificates.
- Application-based Process Isolation may increase memory footprint.
- Application-based Process Isolation may decrease application performance.
Implementation perspective
Application-based Process Isolation should be treated as a technical defensive capability rather than a product checkbox. In practice, teams should define the protected scope, the conditions under which the technique acts, and the observable evidence that demonstrates the intended behavior. For this technique, likely engineering context includes Process, Subroutine.
Use the technique to create a logical or physical boundary that limits access, execution, communication, or movement.
Questions to ask
- What is being isolated, from whom or what, and under which conditions?
- Which flows or operations remain explicitly allowed across the boundary?
- What happens when the isolation mechanism fails or loses policy context?
- How is the boundary tested for alternate paths, bypasses, and unintended dependencies?
Evidence and validation
- Architecture and data-flow diagrams showing the isolation boundary
- Policy, rule, or configuration exports from enforcing components
- Tests of allowed, denied, and failure-state behavior
- Monitoring evidence for boundary violations and policy changes
Common failure patterns
- The intended boundary has undocumented alternate paths or inherited trust relationships.
- Rules accumulate without ownership, review, or removal of obsolete exceptions.
- Isolation is assumed from network location while application, identity, or management paths remain open.
This implementation perspective is original Bare Metal Cyber educational content. It does not replace the official D3FEND definition or establish that a specific product implements the technique.
Technique hierarchy
Top-level family
Parent techniques
Direct child techniques
None listed at this level.
Artifacts and ontology entities
These relationships describe how D3FEND connects a defensive technique to artifacts or other ontology entities. They describe graph semantics, not a product certification.
Explicit technique relationships
Show inferred artifact relationship paths (2)
Offensive-technique relationships
These relationships are generated from D3FEND graph paths and are explicitly experimental. They should be treated as hypotheses for defensive analysis—not as proof that the technique prevents, detects, or removes an offensive behavior.
ATT&CK Enterprise (15)
ATT&CK for ICS (7)
Authoritative sources
- Open this technique on the official D3FEND website ↗
- Open the official ontology resources ↗
- Private application access with browser isolation ↗PatentReference
- Protecting web applications from untrusted endpoints using remote browser isolation ↗PatentReference
- Site Isolation Design Document ↗The Chromium Projects · InternetArticleReference
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