CWE-412 Base Incomplete

Unrestricted Externally Accessible Lock

This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or influence that lock.

Definition

What is CWE-412?

This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or influence that lock.
When an attacker can manipulate a lock—such as a mutex, file lock, or a shared resource used as a lock—they can prevent the application from accessing critical resources or performing essential operations. This effectively creates a denial-of-service condition, as the system remains blocked waiting for a lock it cannot acquire. The severity of this issue escalates if the attacker can hold the lock indefinitely, leading to a permanent disruption of service. Developers must ensure that lock mechanisms are secured within the application's trusted boundary and cannot be created, modified, or sustained by untrusted external sources.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-412

  • CVE-2001-0682

    Program can not execute when attacker obtains a mutex.

  • CVE-2002-1914

    Program can not execute when attacker obtains a lock on a critical output file.

  • CVE-2002-1915

    Program can not execute when attacker obtains a lock on a critical output file.

  • CVE-2002-0051

    Critical file can be opened with exclusive read access by user, preventing application of security policy. Possibly related to improper permissions, large-window race condition.

  • CVE-2000-0338

    Chain: predictable file names used for locking, allowing attacker to create the lock beforehand. Resultant from permissions and randomness.

  • CVE-2000-1198

    Chain: Lock files with predictable names. Resultant from randomness.

  • CVE-2002-1869

    Product does not check if it can write to a log file, allowing attackers to avoid logging by accessing the file using an exclusive lock. Overlaps unchecked error condition. This is not quite CWE-412, but close.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    Identifiziere einen Codepfad, der nicht vertrauenswürdige Eingaben ohne Validierung verarbeitet.

  2. 2

    Erzeuge eine Payload, die das unsichere Verhalten auslöst — Injection, Traversal, Overflow oder Logik-Missbrauch.

  3. 3

    Liefere die Payload über einen normalen Request aus und beobachte die Reaktion der Anwendung.

  4. 4

    Iteriere, bis die Antwort Daten preisgibt, Angreifer-Code ausführt oder Berechtigungen eskaliert.

Verwundbares Codebeispiel

Vulnerable PHP

This code tries to obtain a lock for a file, then writes to it.

Verwundbar PHP 
function writeToLog($message){
  	$logfile = fopen("logFile.log", "a");
```
//attempt to get logfile lock* 
  	if (flock($logfile, LOCK_EX)) {
  	```
  		fwrite($logfile,$message);
```
// unlock logfile* 
  		flock($logfile, LOCK_UN);}
  	else {
  	```
  		print "Could not obtain lock on logFile.log, message not recorded\n";
  	}
  }
  fclose($logFile);
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-412

  • Architecture and Design / Implementation Use any access control that is offered by the functionality that is offering the lock.
  • Architecture and Design / Implementation Use unpredictable names or identifiers for the locks. This might not always be possible or feasible.
  • Architecture and Design Consider modifying your code to use non-blocking synchronization methods.
Erkennungssignale

How to detect CWE-412

White Box

Automated code analysis techniques might not be able to reliably detect this weakness, since the application's behavior and general security model dictate which resource locks are critical. Interpretation of the weakness might require knowledge of the environment, e.g. if the existence of a file is used as a lock, but the file is created in a world-writable directory.

Plexicus Auto-Fix

Plexicus erkennt CWE-412 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-412?

This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or influence that lock.

Wie gravierend ist CWE-412?

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-412 betroffen?

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

Wie kann ich CWE-412 verhindern?

Use any access control that is offered by the functionality that is offering the lock. Use unpredictable names or identifiers for the locks. This might not always be possible or feasible.

Wie erkennt und behebt Plexicus CWE-412?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-412 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-412?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/412.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-412

CWE-667 Parent

Improper Locking

This vulnerability occurs when a program fails to correctly acquire or release a lock on a shared resource, such as a file, database…

CWE-1232 Sibling

Improper Lock Behavior After Power State Transition

This vulnerability occurs when a hardware lock bit, designed to protect critical system configuration registers, is improperly reset or…

CWE-1233 Sibling

Security-Sensitive Hardware Controls with Missing Lock Bit Protection

This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…

CWE-1234 Sibling

Hardware Internal or Debug Modes Allow Override of Locks

Hardware debug modes or internal states can bypass critical system lock protections, allowing unauthorized changes to device configuration.

CWE-413 Sibling

Improper Resource Locking

This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before…

CWE-414 Sibling

Missing Lock Check

This vulnerability occurs when software fails to verify that a proper synchronization lock is active before accessing or modifying a…

CWE-609 Sibling

Double-Checked Locking

Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks…

CWE-764 Sibling

Multiple Locks of a Critical Resource

This vulnerability occurs when a critical resource, such as a file, data structure, or connection, is locked more times than the software…

CWE-765 Sibling

Multiple Unlocks of a Critical Resource

This vulnerability occurs when a critical resource, like a lock or semaphore, is unlocked more times than it was locked, putting the…

Ressourcen

Further reading

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