Improper Isolation or Compartmentalization

Description

This vulnerability occurs when an application fails to enforce strong boundaries between components that operate at different security levels, allowing lower-privileged functions to improperly interact with higher-privileged ones.

Extended Description

At its core, this weakness breaks a fundamental security principle: components with different trust levels should be kept separate. When an application doesn't properly isolate features, data, or processes, a flaw in a low-privilege area can create a bridge that attackers use to reach sensitive, high-privilege areas. Think of it like a building where a broken lock on a janitor's closet somehow gives access to the entire executive suite. For developers, this means that even a minor bug in a user-facing feature can escalate into a major breach if strong compartmentalization isn't in place. To prevent this, you must design clear security boundaries—using mechanisms like process separation, sandboxing, or strict access controls—to ensure that a compromise in one module is contained and cannot spread to more critical parts of the system.

Common Consequences 1

Scope: Access Control

Impact: Gain Privileges or Assume IdentityBypass Protection Mechanism

The exploitation of a weakness in low-privileged areas of the software can be leveraged to reach higher-privileged areas without having to overcome any additional obstacles.

Detection Methods 3

Automated Static Analysis - Binary or BytecodeSOAR Partial

According to SOAR, the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Compare binary / bytecode to application permission manifest

Manual Static Analysis - Source CodeHigh

According to SOAR, the following detection techniques may be useful: ``` Highly cost effective: ``` Manual Source Code Review (not inspections) ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source

Architecture or Design ReviewHigh

According to SOAR, the following detection techniques may be useful: ``` Highly cost effective: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Attack Modeling

Potential Mitigations 1

Phase: Architecture and Design

Break up privileges between different modules, objects, or entities. Minimize the interfaces between modules and require strong access control between them.

Demonstrative Examples 2

ID : DX-167

Single sign-on technology is intended to make it easier for users to access multiple resources or domains without having to authenticate each time. While this is highly convenient for the user and attempts to address problems with psychological acceptability, it also means that a compromise of a user's credentials can provide immediate access to all other resources or domains.

The traditional UNIX privilege model provides root with arbitrary access to all resources, but root is frequently the only user that has privileges. As a result, administrative tasks require root privileges, even if those tasks are limited to a small area, such as updating user manpages. Some UNIX flavors have a "bin" user that is the owner of system executables, but since root relies on executables owned by bin, a compromise of the bin account can be leveraged for root privileges by modifying a bin-owned executable, such as CVE-2007-4238.

Observed Examples 2

CVE-2021-33096Improper isolation of shared resource in a network-on-chip leads to denial of service

CVE-2019-6260Baseboard Management Controller (BMC) device implements Advanced High-performance Bus (AHB) bridges that do not require authentication for arbitrary read and write access to the BMC's physical address space from the host, and possibly the network [REF-1138].

References 4

The Protection of Information in Computer Systems

Jerome H. Saltzer and Michael D. Schroeder

Proceedings of the IEEE 63

09-1975

http://web.mit.edu/Saltzer/www/publications/protection/

ID: REF-196

Separation of Privilege

Sean Barnum and Michael Gegick

06-12-2005

https://web.archive.org/web/20220126060047/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/separation-of-privilege(2023-04-07)

ID: REF-535

CVE-2019-6260: Gaining control of BMC from the host processor

Stewart Smith

2019

https://www.flamingspork.com/blog/2019/01/23/cve-2019-6260:-gaining-control-of-bmc-from-the-host-processor/(2025-07-29)

ID: REF-1138

State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation

Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy

07-2014

https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx(2025-09-05)

ID: REF-1479

Applicable Platforms

Languages:

Not Language-Specific : Undetermined

Modes of Introduction

Architecture and Design

Implementation

Alternate Terms

Separation of Privilege

Some people and publications use the term "Separation of Privilege" to describe this weakness, but this term has dual meanings in current usage. This node conflicts with the original definition of "Separation of Privilege" by Saltzer and Schroeder; that original definition is more closely associated with Reliance on a Single Factor in a Security Decision. Because there are multiple interpretations, use of the "Separation of Privilege" term is discouraged.

Related Weaknesses

ChildOf:

Violation of Secure Design Principles (CWE-657)

ChildOf:

Protection Mechanism Failure (CWE-693)

Notes

RelationshipThere is a close association with Execution with Unnecessary Privileges (Execution with Unnecessary Privileges). Improper Isolation or Compartmentalization is about providing separate components for each "privilege"; Execution with Unnecessary Privileges is about ensuring that each component has the least amount of privileges possible. In this fashion, compartmentalization becomes one mechanism for reducing privileges.

TerminologyThe term "Separation of Privilege" is used in several different ways in the industry, but they generally combine two closely related principles: compartmentalization (this node) and using only one factor in a security decision (Reliance on a Single Factor in a Security Decision). Proper compartmentalization implicitly introduces multiple factors into a security decision, but there can be cases in which multiple factors are required for authentication or other mechanisms that do not involve compartmentalization, such as performing all required checks on a submitted certificate. It is likely that Improper Isolation or Compartmentalization and Reliance on a Single Factor in a Security Decision will provoke further discussion.