Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.
CWE-689 Compound Draft
Permission Race Condition During Resource Copy
This vulnerability occurs when a system copies a file or resource but delays setting its final permissions until the entire copy operation is finished. During the copy process, the resource remains…
Definition
What is CWE-689?
This vulnerability occurs when a system copies a file or resource but delays setting its final permissions until the entire copy operation is finished. During the copy process, the resource remains exposed with default or overly permissive access, creating a temporary window where unauthorized users or processes could read, modify, or delete it.
This race condition is a classic time-of-check to time-of-use (TOCTOU) flaw specific to resource duplication. When an application copies a file—for example, during installation, backup, or user upload—it often creates the new file with broad default permissions (like world-readable) to ensure the copy succeeds. The intended restrictive permissions are only applied after the data transfer is complete. This gap, however brief, is a real security risk, especially on multi-user systems or shared hosting environments where other processes are actively running.
To prevent this, developers should implement atomic operations where possible, such as creating the file with the correct permissions from the outset before writing data. Alternatively, copy operations can be performed in a secure, isolated temporary location with strict access controls, and the file should only be moved to its final destination after both the data and the correct permissions are fully applied, eliminating the exposure window.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-689
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Archive extractor decompresses files with world-readable permissions, then later sets permissions to what the archive specified.
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Product inserts a new object into database before setting the object's permissions, introducing a race condition.
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Error file has weak permissions before a chmod is performed.
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Archive permissions issue using hard link.
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Database product creates files world-writable before initializing the setuid bits, leading to modification of executables.
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-689
- 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-689
Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.
Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.
Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.
Plexicus erkennt CWE-689 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.
Häufig gestellte Fragen Was ist CWE-689?
Wie gravierend ist CWE-689?
Welche Sprachen oder Plattformen sind von CWE-689 betroffen?
Wie kann ich CWE-689 verhindern?
Wie erkennt und behebt Plexicus CWE-689?
Wo erfahre ich mehr über CWE-689?
Frequently asked questions
Was ist CWE-689?
This vulnerability occurs when a system copies a file or resource but delays setting its final permissions until the entire copy operation is finished. During the copy process, the resource remains exposed with default or overly permissive access, creating a temporary window where unauthorized users or processes could read, modify, or delete it.
Wie gravierend ist CWE-689?
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-689 betroffen?
MITRE lists the following affected platforms: C, Perl.
Wie kann ich CWE-689 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-689?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-689 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-689?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/689.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-689
CWE-362 Parent
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
A race condition occurs when multiple processes or threads access a shared resource simultaneously without proper coordination, creating a…
CWE-1223 Sibling
Race Condition for Write-Once Attributes
This vulnerability occurs when an untrusted software component wins a race condition and writes to a hardware register before the trusted…
CWE-1298 Sibling
Hardware Logic Contains Race Conditions
A hardware race condition occurs when security-critical logic circuits receive signals at slightly different times, creating temporary…
CWE-364 Sibling
Signal Handler Race Condition
A signal handler race condition occurs when a program's signal handling routine is vulnerable to timing issues, allowing its state to be…
CWE-366 Sibling
Race Condition within a Thread
This vulnerability occurs when two or more threads within the same application access and manipulate a shared resource (like a variable,…
CWE-367 Sibling
Time-of-check Time-of-use (TOCTOU) Race Condition
This vulnerability occurs when a program verifies a resource's state (like a file's permissions or existence) but then uses it after that…
CWE-368 Sibling
Context Switching Race Condition
This vulnerability occurs when an application switches between different security contexts (like privilege levels or domains) using a…
CWE-421 Sibling
Race Condition During Access to Alternate Channel
A race condition occurs when an application opens a secondary communication channel intended for an authorized user, but fails to secure…
CWE-732 Peer
Incorrect Permission Assignment for Critical Resource
This vulnerability occurs when a system grants overly permissive access to a sensitive resource, allowing unauthorized users or processes…
Ressourcen
Further reading
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