CWE-669 Class Draft

Incorrect Resource Transfer Between Spheres

Definition

What is CWE-669?

This vulnerability occurs when an application incorrectly moves or shares a resource (like data, permissions, or functionality) between different trust boundaries or security contexts. This improper transfer can give unintended actors control over that resource, leading to security breaches.

Think of your application as having separate, secure zones—like a user interface (client-side), a backend server, and an administrative panel. Each zone has its own level of trust and permitted actions. This weakness happens when a resource, such as a user session, a file handle, or an administrative function, is mistakenly allowed to cross from a less-trusted zone into a more-trusted one, or is imported without proper validation. For example, a web application might incorrectly accept and process a user-supplied file path as if it originated from the secure server itself, allowing an attacker to access sensitive system files. To prevent this, developers must enforce strict boundaries between different spheres of control. Always validate and sanitize any resource that moves between contexts, explicitly check the origin of requests, and implement the principle of least privilege so that resources can only be used within their intended security scope. Auditing data flows and trust transitions in your architecture is key to identifying and fixing these improper transfers.

Auswirkungen in der Praxis

Real-world CVEs caused by CWE-669

CVE-2021-22909

Chain: router's firmware update procedure uses curl with "-k" (insecure) option that disables certificate validation (CWE-295), allowing adversary-in-the-middle (AITM) compromise with a malicious firmware image (CWE-494).
CVE-2023-5227

PHP-based FAQ management app does not check the MIME type for uploaded images
CVE-2005-0406

Some image editors modify a JPEG image, but the original EXIF thumbnail image is left intact within the JPEG. (Also an interaction error).

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

1
The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.
2
When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.
3
This code does not perform a check on the type of the file being uploaded (CWE-434). This could allow an attacker to upload any executable file or other file with malicious code.
4
Additionally, the creation of the BufferedWriter object is subject to relative path traversal (CWE-23). Since the code does not check the filename that is provided in the header, an attacker can use "../" sequences to write to files outside of the intended directory. Depending on the executing environment, the attacker may be able to specify arbitrary files to write to, leading to a wide variety of consequences, from code execution, XSS (CWE-79), or system crash.
5
This code includes an external script to get database credentials, then authenticates a user against the database, allowing access to the application.

Verwundbares Codebeispiel

Vulnerable Java

When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.

Verwundbar Java

public class FileUploadServlet extends HttpServlet {
  		...
  		protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  				response.setContentType("text/html");
  				PrintWriter out = response.getWriter();
  				String contentType = request.getContentType();
  				// the starting position of the boundary header
  				int ind = contentType.indexOf("boundary=");
  				String boundary = contentType.substring(ind+9);
  				String pLine = new String();
  				String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value
  				// verify that content type is multipart form data
  				if (contentType != null && contentType.indexOf("multipart/form-data") != -1) {
  						// extract the filename from the Http header
  						BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
  						...
  						pLine = br.readLine();
  						String filename = pLine.substring(pLine.lastIndexOf("\\"), pLine.lastIndexOf("\""));
  						...
  						// output the file to the local upload directory
  						try {
  								BufferedWriter bw = new BufferedWriter(new FileWriter(uploadLocation+filename, true));
  								for (String line; (line=br.readLine())!=null; ) {
  									if (line.indexOf(boundary) == -1) {
  										bw.write(line);
  										bw.newLine();
  										bw.flush();
  									}
  								} //end of for loop
  								bw.close();
  						} catch (IOException ex) {...}
  						// output successful upload response HTML page
  				}
  				// output unsuccessful upload response HTML page
  				else
  				{...}
  		}
  			...
  }

Sicheres Codebeispiel

Secure HTML

The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.

Sicher HTML

<form action="FileUploadServlet" method="post" enctype="multipart/form-data">
  Choose a file to upload:
  <input type="file" name="filename"/>
  <br/>
  <input type="submit" name="submit" value="Submit"/>
  </form>

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-669

Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
Implementation Validate input at trust boundaries; use allowlists, not denylists.
Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
Operation Monitor logs for the runtime signals listed in the next section.

Erkennungssignale

How to detect CWE-669

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-669 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-669?

Wie gravierend ist CWE-669?

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-669 betroffen?

MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.

Wie kann ich CWE-669 verhindern?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Wie erkennt und behebt Plexicus CWE-669?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-669 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-669?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/669.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-669

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

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