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CWE-53 Variant Incomplete
Path Equivalence: '\multiple\\internal\backslash'
This vulnerability occurs when an application accepts file paths containing sequences of multiple internal backslashes (like '\multiple\\internal\\backslash') without properly normalizing them. This…
Definition
What is CWE-53?
This vulnerability occurs when an application accepts file paths containing sequences of multiple internal backslashes (like '\multiple\\internal\\backslash') without properly normalizing them. This can confuse the system's path resolution logic, potentially allowing attackers to access files or directories outside the intended scope.
When a system processes a file path, it typically uses a single backslash as a directory separator on Windows. However, sequences of multiple consecutive backslashes (e.g., 'C:\\folder\\\subfolder') can create ambiguity. Different operating system functions or parsing libraries may interpret these sequences inconsistently—some might collapse them, while others treat them as a special namespace or produce unexpected navigation. This inconsistency is the core weakness that attackers can probe and exploit.
To prevent this, developers should implement strict path validation and canonicalization. Always normalize paths by resolving sequences of multiple backslashes to a single separator before any file system operations. Combine this with other defenses like whitelisting allowed directories, using safe API functions that prevent traversal, and running the application with the least necessary file system permissions. This layered approach closes the gap between how the application sees the path and how the underlying OS interprets it.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-53
Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.
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-53
- Implementation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Erkennungssignale
How to detect CWE-53
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.
CWE-53
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-53?
Wie gravierend ist CWE-53?
Welche Sprachen oder Plattformen sind von CWE-53 betroffen?
Wie kann ich CWE-53 verhindern?
Wie erkennt und behebt Plexicus CWE-53?
Wo erfahre ich mehr über CWE-53?
Frequently asked questions
Was ist CWE-53?
This vulnerability occurs when an application accepts file paths containing sequences of multiple internal backslashes (like '\multiple\\internal\\backslash') without properly normalizing them. This can confuse the system's path resolution logic, potentially allowing attackers to access files or directories outside the intended scope.
Wie gravierend ist CWE-53?
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-53 betroffen?
MITRE hat für diese CWE keine betroffenen Plattformen spezifiziert — sie kann in den meisten Anwendungs-Stacks auftreten.
Wie kann ich CWE-53 verhindern?
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Wie erkennt und behebt Plexicus CWE-53?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-53 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-53?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/53.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-53
CWE-41 Parent
Improper Resolution of Path Equivalence
This vulnerability occurs when an application fails to properly handle different text representations that refer to the same file or…
CWE-42 Sibling
Path Equivalence: 'filename.' (Trailing Dot)
This vulnerability occurs when a system accepts file or directory paths that end with a dot (like 'file.txt.' or 'folder.') without…
CWE-44 Sibling
Path Equivalence: 'file.name' (Internal Dot)
This vulnerability occurs when an application accepts file paths containing internal dots (like 'file.ordir') without properly checking…
CWE-46 Sibling
Path Equivalence: 'filename ' (Trailing Space)
This vulnerability occurs when an application processes file paths that end with a space character (like 'document.txt ') without properly…
CWE-47 Sibling
Path Equivalence: ' filename' (Leading Space)
This vulnerability occurs when an application accepts file or directory paths that begin with a space character (like ' filename'),…
CWE-48 Sibling
Path Equivalence: 'file name' (Internal Whitespace)
This vulnerability occurs when an application accepts file paths containing internal spaces (like 'file name') without proper validation.…
CWE-49 Sibling
Path Equivalence: 'filename/' (Trailing Slash)
This vulnerability occurs when an application accepts file or directory paths that end with a slash (e.g., 'documents/') without properly…
CWE-50 Sibling
Path Equivalence: '//multiple/leading/slash'
This vulnerability occurs when an application accepts file or directory paths containing multiple leading slashes (like…
CWE-51 Sibling
Path Equivalence: '/multiple//internal/slash'
This vulnerability occurs when an application accepts file or directory paths containing multiple consecutive forward slashes (e.g.,…
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Bereit zu validieren, was zählt.
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