Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
CWE-913 Class Incomplete
Improper Control of Dynamically-Managed Code Resources
This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.
Definition
What is CWE-913?
This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.
Many modern programming languages provide powerful features for dynamic code manipulation, allowing developers to generate or modify code, objects, and functions while the application is running. While these capabilities offer great flexibility and can speed up development, they introduce significant risk if an attacker can influence what gets created or changed.
Without strict controls, an attacker could inject malicious logic, alter critical data structures, or bypass security checks by manipulating these dynamic resources. To prevent this, developers must implement strong validation, enforce strict access controls, and avoid using user input directly in dynamic code operations.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-913
-
Python compiler uses eval() to execute malicious strings as Python code.
-
Cryptography API uses unsafe reflection when deserializing a private key
-
Deserialization issue in commonly-used Java library allows remote execution.
-
Chain: extract used for register_globals compatibility layer, enables path traversal (CWE-22)
-
Source version control product allows modification of trusted key using mass assignment.
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.
- 2
Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.
- 3
Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.
- 4
Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.
Verwundbares Codebeispiel
Vulnerable pseudo
MITRE hat kein Codebeispiel für diese CWE veröffentlicht. Das untenstehende Muster ist illustrativ — kanonische Referenzen findest du unter Ressourcen.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Sicheres Codebeispiel
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} 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-913
- Implementation For any externally-influenced input, check the input against an allowlist of acceptable values.
- Implementation / Architecture and Design Refactor the code so that it does not need to be dynamically managed.
Erkennungssignale
How to detect CWE-913
CWE-913
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.
Häufig gestellte Fragen Was ist CWE-913?
Wie gravierend ist CWE-913?
Welche Sprachen oder Plattformen sind von CWE-913 betroffen?
Wie kann ich CWE-913 verhindern?
Wie erkennt und behebt Plexicus CWE-913?
Wo erfahre ich mehr über CWE-913?
Frequently asked questions
Was ist CWE-913?
This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.
Wie gravierend ist CWE-913?
MITRE hat für diese Schwachstelle keine Exploit-Wahrscheinlichkeit veröffentlicht. Behandle sie als mittlere Auswirkung, bis dein Threat Model anderes belegt.
Welche Sprachen oder Plattformen sind von CWE-913 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-913 verhindern?
For any externally-influenced input, check the input against an allowlist of acceptable values. Refactor the code so that it does not need to be dynamically managed.
Wie erkennt und behebt Plexicus CWE-913?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-913 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-913?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/913.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-913
CWE-664 Parent
Improper Control of a Resource Through its Lifetime
This vulnerability occurs when software fails to properly manage a resource throughout its entire lifecycle—from creation and active use…
CWE-118 Sibling
Incorrect Access of Indexable Resource ('Range Error')
This vulnerability occurs when software fails to properly check the boundaries of an indexed resource, like an array, buffer, or file,…
CWE-1229 Sibling
Creation of Emergent Resource
This vulnerability occurs when a system's normal operations unintentionally create new, exploitable resources that attackers can use to…
CWE-1250 Sibling
Improper Preservation of Consistency Between Independent Representations of Shared State
This vulnerability occurs when a system with multiple independent components (like distributed services or separate hardware units) each…
CWE-1329 Sibling
Reliance on Component That is Not Updateable
This vulnerability occurs when a product depends on a component that cannot be updated or patched to fix security flaws or critical bugs.
CWE-221 Sibling
Information Loss or Omission
This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security…
CWE-372 Sibling
Incomplete Internal State Distinction
This vulnerability occurs when an application fails to accurately track its own operational state. The system incorrectly assumes it's in…
CWE-400 Sibling
Uncontrolled Resource Consumption
This vulnerability occurs when an application fails to properly manage a finite resource, allowing an attacker to exhaust it and cause a…
CWE-404 Sibling
Improper Resource Shutdown or Release
This vulnerability occurs when a program fails to properly close or release a system resource—like a file handle, database connection, or…
Ressourcen
Further reading
Bereit, das Wesentliche zu validieren?
Bereit zu validieren, was zählt.
Plexicus ist Proof-Driven AppSec: validierte Funde, kontextuelles Verständnis und geprüfte Remediation — in Evidenz verankert, mit Ihnen gescoped.