What is Unrestricted Externally Accessible Lock (CWE-412)?

TL;DR: Unrestricted Externally Accessible Lock (CWE-412) is a security misconfiguration where external actors can control or influence application locks, leading to potential denial-of-service attacks. To mitigate this risk, implement strict access controls and unpredictable identifiers for these locks.

What is Unrestricted Externally Accessible Lock?

Unrestricted Externally Accessible Lock (CWE-412) is a type of security misconfiguration vulnerability that occurs when locks can be controlled or influenced by external actors. As defined by the MITRE Corporation under CWE-412, and classified by the OWASP Foundation as not directly mapped to an official category.

Quick Summary

Unrestricted Externally Accessible Lock allows attackers to manipulate application resources through externally accessible locks, leading to potential denial-of-service attacks and resource consumption issues. This vulnerability can significantly impact system availability and integrity. Jump to: Overview · How It Works · Business Impact · Attack Scenario · Detection · Fix · Framework-Specific Fixes · AI Check · Best Practices · FAQ · Related Vulnerabilities

Jump to: Quick Summary · Unrestricted Externally Accessible Lock Overview · How Unrestricted Externally Accessible Lock Works · Business Impact of Unrestricted Externally Accessible Lock · Unrestricted Externally Accessible Lock Attack Scenario · How to Detect Unrestricted Externally Accessible Lock · How to Fix Unrestricted Externally Accessible Lock · Framework-Specific Fixes for Unrestricted Externally Accessible Lock · How to Ask AI to Check Your Code for Unrestricted Externally Accessible Lock · Unrestricted Externally Accessible Lock Best Practices Checklist · Unrestricted Externally Accessible Lock FAQ · Vulnerabilities Related to Unrestricted Externally Accessible Lock · References · Scan Your Own Site

Unrestricted Externally Accessible Lock Overview

What: A security misconfiguration where locks can be controlled or influenced by external actors.

Why it matters: This vulnerability allows attackers to manipulate resources, leading to potential denial-of-service attacks and resource consumption issues.

Where it occurs: In applications that improperly manage access control for externally accessible locks.

Who is affected: Any system with externally accessible locks that lack proper security controls.

Who is NOT affected: Systems where locks are managed internally and not exposed to external influence.

How Unrestricted Externally Accessible Lock Works

Root Cause

The root cause of this vulnerability lies in the improper management of access control for externally accessible locks. When an actor outside the intended sphere of control can manipulate a lock, it leads to potential denial-of-service conditions by blocking resources indefinitely.

Attack Flow

1. An attacker identifies an externally accessible lock.
2. The attacker gains unauthorized control over the lock.
3. The attacker uses this control to block or influence resource management operations.
4. This manipulation results in indefinite blocking and denial-of-service conditions for other users of the system.

Prerequisites to Exploit

• External access to a lock that is not properly secured.
• Lack of robust access controls on externally accessible locks.

Vulnerable Code

public void manageResource(String lockName) {
    // Lock management logic without proper access control checks
}

This code snippet demonstrates the absence of necessary security measures to prevent external actors from controlling or influencing the lock.

Secure Code

public void manageResource(String lockName) {
    if (!isLockAccessible(lockName)) {
        throw new SecurityException("Access denied for external lock management.");
    }
    // Lock management logic with proper access control checks
}

The secure version ensures that only authorized actors can manage the locks, mitigating the risk of unauthorized control.

Business Impact of Unrestricted Externally Accessible Lock

Availability:

• Indefinite blocking of resources leading to denial-of-service conditions.
• Significant disruption in service availability for legitimate users.

Real-world Consequences

• Financial losses due to system downtime.
• Compliance violations from unavailability breaches.
• Reputation damage from perceived lack of security and reliability.

Unrestricted Externally Accessible Lock Attack Scenario

1. An attacker identifies a publicly accessible lock used in resource management.
2. The attacker gains unauthorized control over the lock through external manipulation.
3. Using this control, the attacker blocks or influences resource allocation indefinitely.
4. This results in denial-of-service conditions for legitimate users attempting to access resources.

How to Detect Unrestricted Externally Accessible Lock

Manual Testing

• Check if locks are accessible from outside the intended sphere of control.
• Verify that proper access controls and validation checks are implemented on externally accessible locks.
• Test scenarios where external actors can manipulate lock states.

Automated Scanners (SAST / DAST)

Static analysis tools can identify patterns indicative of improperly managed locks, while dynamic scanners can simulate attacks to verify the presence of this vulnerability.

PenScan Detection

PenScan’s scanner engines such as ZAP and Wapiti actively detect externally accessible locks that lack proper security controls.

False Positive Guidance

False positives may occur when a lock is intended to be externally accessible for legitimate purposes. Ensure that any detected pattern is actually exploitable by verifying the context in which it appears.

How to Fix Unrestricted Externally Accessible Lock

• Implement robust access control mechanisms on externally accessible locks.
• Use unpredictable names or identifiers for these locks to mitigate unauthorized influence.
• Consider modifying code to use non-blocking synchronization methods where feasible.
• Ensure that all external lock management operations are validated against a strict security policy.

Framework-Specific Fixes for Unrestricted Externally Accessible Lock

Java

public void manageResource(String lockName) {
    if (!isLockAccessible(lockName)) {
        throw new SecurityException("Access denied for external lock management.");
    }
    // Lock management logic with proper access control checks
}

Node.js

function manageResource(lockName) {
    if (!isLockAccessible(lockName)) {
        throw new Error('Access denied for external lock management.');
    }
    // Lock management logic with proper access control checks
}

Python/Django

def manage_resource(lock_name):
    if not is_lock_accessible(lock_name):
        raise PermissionDenied("Access denied for external lock management.")
    # Lock management logic with proper access control checks

How to Ask AI to Check Your Code for Unrestricted Externally Accessible Lock

Unrestricted Externally Accessible Lock Best Practices Checklist

✅ Implement strict access controls on externally accessible locks. ✅ Use unpredictable names or identifiers to mitigate unauthorized influence. ✅ Validate all external lock management operations against a security policy. ✅ Consider non-blocking synchronization methods where feasible.

Unrestricted Externally Accessible Lock FAQ

How does an attacker exploit Unrestricted Externally Accessible Lock?

An attacker can control or influence a lock that is externally accessible, leading to potential denial of service attacks by blocking resources indefinitely.

What are the common consequences of Unrestricted Externally Accessible Lock?

This vulnerability can cause resource consumption issues and lead to denial-of-service conditions affecting availability.

How do you detect Unrestricted Externally Accessible Lock in your application?

Detecting this issue requires checking for locks that are accessible from outside the intended control sphere, often through manual code reviews or automated scanners.

What is a real-world example of Unrestricted Externally Accessible Lock?

A common scenario involves an external actor controlling a lock used in resource management, leading to indefinite blocking and denial-of-service conditions.

How can you prevent Unrestricted Externally Accessible Lock vulnerabilities?

Implement access controls on locks that are externally accessible and use unpredictable names or identifiers for these locks to mitigate the risk of unauthorized control.

What is the impact of Unrestricted Externally Accessible Lock on system availability?

The vulnerability can cause denial-of-service conditions by blocking resources indefinitely, impacting system availability significantly.

How does Unrestricted Externally Accessible Lock relate to other security issues?

This issue often coexists with improper locking (CWE-667) and insufficient resource pool management (CWE-410).

Vulnerabilities Related to Unrestricted Externally Accessible Lock

References

• MITRE
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Unrestricted Externally Accessible Lock and other risks before an attacker does.