Class Hierarchy Analysis is a static analysis technique used to resolve method calls by examining inheritance relationships. It helps approximate which method implementations may be invoked at runtime in object oriented code, especially when direct call targets are not obvious from the source alone.
How Class Hierarchy Analysis works
Class Hierarchy Analysis, or CHA, is a whole-program reasoning technique for object-oriented code. It inspects declared inheritance and interface relationships to estimate which method implementations a virtual call might reach. That makes it useful for building call graphs, especially when dynamic dispatch prevents a compiler or analyst from seeing the exact target directly.
CHA is intentionally conservative. If a subclass could override a method, that implementation is treated as a possible target even when the runtime never chooses it in practice. The result is usually more complete than a narrow syntactic scan, but less precise than analyses that also track points-to information or runtime type flow.
Why it is used in static analysis
The main value of CHA is scale. It can approximate dispatch targets quickly because it relies on type structure rather than expensive execution modelling. Security tools, optimization passes, refactoring aids and program-understanding pipelines all use that property when they need a fast over-approximation of call relationships across a large codebase.
Because the method is conservative, it tends to preserve possible behaviour rather than miss it. That is especially important in the presence of polymorphism, abstract base classes and inherited interfaces, where the source call site may reveal the receiver type only indirectly. For analysis workflows, a broad but explainable answer is often preferable to a brittle exact one.
Strengths and limitations
CHA is strongest when class structure is stable and the codebase uses conventional inheritance patterns. It is easy to explain, easy to implement and cheap enough to run early in a toolchain. It also provides a useful baseline against which more precise analyses can be compared.
Its weakness is precision. Any subclass that could theoretically satisfy a call becomes part of the candidate set, even if the program never instantiates that type at runtime. In systems with deep hierarchies, heavy framework use or plugin-style extensibility, that can produce many false positives and a much larger call graph than the real execution paths require.
That trade-off matters because downstream analyses inherit the same approximation. If CHA feeds a vulnerability scanner, taint analysis or reachability check, the next stage may need extra filtering to avoid overwhelming the reader with non-executable paths.
Where it fits in practice
In practice, CHA is often the first pass in a layered analysis strategy. It establishes a safe upper bound on possible dispatch targets, then more precise techniques refine that set using runtime type constraints, points-to information or observed execution behaviour. Used this way, it gives analysts a dependable starting point without pretending to be fully exact.
It is also a reminder that object-oriented design choices affect analyzability. Wider inheritance trees, extensive interface polymorphism and framework-driven inversion of control all make static target resolution harder. When teams understand that constraint, they can choose the right precision level for the task rather than assuming one static method-call model fits every use case.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP ASVS, NIST SP 800-53 Rev 5 and OWASP SAMM set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP ASVS | V15 — Secure Coding and Architecture | CHA supports secure code analysis of object-oriented dispatch and reachable code paths. |
| Recommendation — Use V15 to examine polymorphic call paths when reviewing code for security-impacting design flaws. | ||
| NIST SP 800-53 Rev 5 | RA-5 — Vulnerability Monitoring and Scanning | Static reachability analysis helps identify code paths that deserve vulnerability review. |
| Recommendation — Apply RA-5 to prioritize code paths and components that static analysis marks as potentially reachable. | ||
| OWASP SAMM | DS — Design Security | CHA informs design-time understanding of inheritance-driven behaviour and analysis precision. |
| Recommendation — Use DS to account for polymorphism and inheritance when designing analyzable software architectures. | ||
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Reviewed and updated by the NHIMG editorial team on October 30, 2026.
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