CWE-767 Base Incomplete

Access to Critical Private Variable via Public Method

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.

Definition

What is CWE-767?

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.
Exposing a private variable through a public method breaks a core principle of encapsulation. It allows external code, including potential attacker-controlled inputs, to bypass intended controls and directly manipulate sensitive internal data. This can lead to the variable holding values the rest of the codebase never expects, corrupting the application's state and violating critical security assumptions. Beyond unexpected modification, this flaw can also lead to information disclosure. An attacker might use the public method to read the private variable's contents, potentially leaking sensitive data like internal flags, cryptographic keys, or user information. This exposed data not only compromises confidentiality but can also provide attackers with the insights needed to craft more sophisticated and targeted follow-up attacks.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-767

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

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

  2. 2

    The following example could be used to implement a user forum where a single user (UID) can switch between multiple profiles (PID).

  3. 3

    The programmer implemented setPID with the intention of modifying the PID variable, but due to a typo. accidentally specified the critical variable UID instead. If the program allows profile IDs to be between 1 and 10, but a UID of 1 means the user is treated as an admin, then a user could gain administrative privileges as a result of this typo.

Verwundbares Codebeispiel

Vulnerable C++

The following example declares a critical variable to be private, and then allows the variable to be modified by public methods.

Verwundbar C++ 
private: float price;
  public: void changePrice(float newPrice) {
  	price = newPrice;
  }
Sicheres Codebeispiel

Secure pseudo

Sicher 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-767

  • Implementation Use class accessor and mutator methods appropriately. Perform validation when accepting data from a public method that is intended to modify a critical private variable. Also be sure that appropriate access controls are being applied when a public method interfaces with critical data.
Erkennungssignale

How to detect CWE-767

SAST High

Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.

DAST Moderate

Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.

Runtime Moderate

Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.

Code review Moderate

Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.

Plexicus Auto-Fix

Plexicus erkennt CWE-767 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen
Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-767?

This vulnerability occurs when a class exposes a public method that directly accesses or alters a private variable.

Wie gravierend ist CWE-767?

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-767 betroffen?

MITRE lists the following affected platforms: C++, C#, Java.

Wie kann ich CWE-767 verhindern?

Use class accessor and mutator methods appropriately. Perform validation when accepting data from a public method that is intended to modify a critical private variable. Also be sure that appropriate access controls are being applied when a public method interfaces with critical data.

Wie erkennt und behebt Plexicus CWE-767?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-767 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-767?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/767.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-767

CWE-668 Parent

Exposure of Resource to Wrong Sphere

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CWE-1189 Sibling

Improper Isolation of Shared Resources on System-on-a-Chip (SoC)

This vulnerability occurs when a System-on-a-Chip (SoC) fails to properly separate shared hardware resources between secure (trusted) and…

CWE-1282 Sibling

Assumed-Immutable Data is Stored in Writable Memory

This vulnerability occurs when data that should be permanent and unchangeable—like a bootloader, device IDs, or one-time configuration…

CWE-1327 Sibling

Binding to an Unrestricted IP Address

This vulnerability occurs when software or a service is configured to bind to the IP address 0.0.0.0 (or :: in IPv6), which acts as a…

CWE-1331 Sibling

Improper Isolation of Shared Resources in Network On Chip (NoC)

This vulnerability occurs when a Network on Chip (NoC) fails to properly separate its internal, shared resources—like buffers, switches,…

CWE-134 Sibling

Use of Externally-Controlled Format String

This vulnerability occurs when a program uses a format string from an untrusted, external source (like user input, a network packet, or a…

CWE-200 Sibling

Exposure of Sensitive Information to an Unauthorized Actor

This weakness occurs when an application unintentionally reveals sensitive data to someone who shouldn't have access to it.

CWE-374 Sibling

Passing Mutable Objects to an Untrusted Method

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy…

CWE-375 Sibling

Returning a Mutable Object to an Untrusted Caller

This vulnerability occurs when a method directly returns a reference to its internal mutable data, allowing untrusted calling code to…

Ressourcen

Further reading

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