CWE-492 詳細

Inner classes are translated into classes that are accessible at package scope and may expose code that the programmer intended to keep private to attackers.

Inner classes quietly introduce several security concerns because of the way they are translated into Java bytecode. In Java source code, it appears that an inner class can be declared to be accessible only by the enclosing class, but Java bytecode has no concept of an inner class, so the compiler must transform an inner class declaration into a peer class with package level access to the original outer class. More insidiously, since an inner class can access private fields in its enclosing class, once an inner class becomes a peer class in bytecode, the compiler converts private fields accessed by the inner class into protected fields.

導入モード

Implementation

適用可能なプラットフォーム

言語

名前： Java (Undetermined)

一般的な結果

潜在的な緩和策

Phases : Implementation
Using sealed classes protects object-oriented encapsulation paradigms and therefore protects code from being extended in unforeseen ways.
Phases : Implementation
Inner Classes do not provide security. Warning: Never reduce the security of the object from an outer class, going to an inner class. If an outer class is final or private, ensure that its inner class is private as well.

検出方法

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
有効性 : High

脆弱性マッピングノート

理由 : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
コメント : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

ノート

Mobile code, in this case a Java Applet, is code that is transmitted across a network and executed on a remote machine. Because mobile code developers have little if any control of the environment in which their code will execute, special security concerns become relevant. One of the biggest environmental threats results from the risk that the mobile code will run side-by-side with other, potentially malicious, mobile code. Because all of the popular web browsers execute code from multiple sources together in the same JVM, many of the security guidelines for mobile code are focused on preventing manipulation of your objects' state and behavior by adversaries who have access to the same virtual machine where your program is running.

参考文献

REF-6

Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors
Katrina Tsipenyuk, Brian Chess, Gary McGraw.
https://cwe.mitre.org/documents/sources/SevenPerniciousKingdoms.pdf

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