CWE-486: Comparison of Classes by Name

Definition

What is CWE-486?

This vulnerability occurs when an application determines an object's trustworthiness or behavior solely by checking its class name. Since multiple classes can share identical names across different packages or classloaders, this comparison can lead to using the wrong, potentially malicious, class.

Relying on class name strings for security decisions is inherently risky. Attackers can craft classes with names identical to your trusted ones, tricking your application into granting them unauthorized privileges or executing unintended code paths. This is especially problematic in environments with multiple classloaders, like application servers, where the same fully-qualified name can point to completely different implementations. Detecting these logical flaws manually is challenging, as they depend on runtime context. While SAST tools can flag dangerous comparison patterns, Plexicus uses AI to not only identify the risk but also suggest specific, secure refactoring—such as using direct class object comparisons or verifying the classloader—saving significant manual review time and preventing impersonation attacks.

Auswirkungen in der Praxis

Real-world CVEs caused by CWE-486

Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

1
In this example, the expression in the if statement compares the class of the inputClass object to a trusted class by comparing the class names.
2
However, multiple classes can have the same name therefore comparing an object's class by name can allow untrusted classes of the same name as the trusted class to be use to execute unintended or incorrect code. To compare the class of an object to the intended class the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.
3
In this example, the Java class, TrustedClass, overrides the equals method of the parent class Object to determine equivalence of objects of the class. The overridden equals method first determines if the object, obj, is the same class as the TrustedClass object and then compares the object's fields to determine if the objects are equivalent.
4
However, the equals method compares the class names of the object, obj, and the TrustedClass object to determine if they are the same class. As with the previous example using the name of the class to compare the class of objects can lead to the execution of unintended or incorrect code if the object passed to the equals method is of another class with the same name. To compare the class of an object to the intended class, the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.

Verwundbares Codebeispiel

Vulnerable Java

In this example, the expression in the if statement compares the class of the inputClass object to a trusted class by comparing the class names.

Verwundbar Java

if (inputClass.getClass().getName().equals("TrustedClassName")) {
```
// Do something assuming you trust inputClass* 
  		
  		
  		 *// ...* 
  		}

Sicheres Codebeispiel

Secure Java

However, multiple classes can have the same name therefore comparing an object's class by name can allow untrusted classes of the same name as the trusted class to be use to execute unintended or incorrect code. To compare the class of an object to the intended class the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.

Sicher Java

if (inputClass.getClass() == TrustedClass.class) {
```
// Do something assuming you trust inputClass* 
  		
  		
  		 *// ...* 
  		}

What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.

Präventions-Checkliste

How to prevent CWE-486

Implementation Use class equivalency to determine type. Rather than use the class name to determine if an object is of a given type, use the getClass() method, and == operator.

Erkennungssignale

How to detect CWE-486

Automated Static Analysis High

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.)

CWE-486

Don't catalog this weakness. Prove it's reachable.

Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.

Request AI Swarm Pentest

Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-486?

This vulnerability occurs when an application determines an object's trustworthiness or behavior solely by checking its class name. Since multiple classes can share identical names across different packages or classloaders, this comparison can lead to using the wrong, potentially malicious, class.

Wie gravierend ist CWE-486?

MITRE stuft die Exploit-Wahrscheinlichkeit als hoch ein — diese Schwachstelle wird aktiv in freier Wildbahn ausgenutzt und sollte priorisiert behoben werden.

Welche Sprachen oder Plattformen sind von CWE-486 betroffen?

MITRE lists the following affected platforms: Java.

Wie kann ich CWE-486 verhindern?

Use class equivalency to determine type. Rather than use the class name to determine if an object is of a given type, use the getClass() method, and == operator.

Wie erkennt und behebt Plexicus CWE-486?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-486 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-486?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/486.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-486

CWE-1025 Parent

Comparison Using Wrong Factors

This weakness occurs when a program compares two items but checks the wrong properties or attributes. This flawed comparison leads to…

CWE-595 Sibling

Comparison of Object References Instead of Object Contents

This vulnerability occurs when code incorrectly checks if two object references point to the same memory location, rather than comparing…

Ressourcen

Bereit zu validieren, was zählt.

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Comparison of Classes by Name