What is Sensitive Information in Resource Not (CWE-226)?

TL;DR: Sensitive Information in Resource Not Removed Before Reuse (CWE-226) occurs when sensitive data remains accessible after a resource is released for reuse, compromising confidentiality. Clearing or overwriting this data prevents unauthorized access.

What is Sensitive Information in Resource Not Removed Before Reuse?

Sensitive Information in Resource Not Removed Before Reuse (CWE-226) is a type of vulnerability where sensitive data remains accessible after a resource has been released for reuse. As defined by the MITRE Corporation under CWE-226, and classified by the OWASP Foundation as not directly mapped to their Top 10 list.

Quick Summary

Sensitive Information in Resource Not Removed Before Reuse is critical because it can expose sensitive data to unauthorized access when a resource is reused without proper cleanup. This vulnerability affects applications that do not clear or overwrite sensitive information before releasing resources for reuse, leading to potential confidentiality breaches.

Jump to: Quick Summary · Sensitive Information in Resource Not Removed Before Reuse Overview · How Sensitive Information in Resource Not Removed Before Reuse Works · Business Impact of Sensitive Information in Resource Not Removed Before Reuse · Sensitive Information in Resource Not Removed Before Reuse Attack Scenario · How to Detect Sensitive Information in Resource Not Removed Before Reuse · How to Fix Sensitive Information in Resource Not Removed Before Reuse · Framework-Specific Fixes for Sensitive Information in Resource Not Removed Before Reuse · How to Ask AI to Check Your Code for Sensitive Information in Resource Not Removed Before Reuse · Sensitive Information in Resource Not Removed Before Reuse Best Practices Checklist · Sensitive Information in Resource Not Removed Before Reuse FAQ · Vulnerabilities Related to Sensitive Information in Resource Not Removed Before Reuse · References · Scan Your Own Site

Sensitive Information in Resource Not Removed Before Reuse Overview

What: A vulnerability where sensitive data remains accessible after a resource is released for reuse.

Why it matters: This can lead to unauthorized access and exposure of sensitive information, compromising confidentiality.

Where it occurs: Applications that do not clear or overwrite sensitive information before releasing resources for reuse.

Who is affected: Developers and organizations using applications with this vulnerability.

Who is NOT affected: Systems already implementing proper cleanup mechanisms.

How Sensitive Information in Resource Not Removed Before Reuse Works

Root Cause

The root cause lies in the failure to properly clear or overwrite sensitive data before releasing a resource for reuse. This can occur during critical state transitions where information not needed in the next state should be removed.

Attack Flow

1. An attacker identifies that sensitive data remains accessible after a resource is released.
2. The attacker exploits this by accessing the residual data from the reused resource.
3. Sensitive information is compromised due to lack of proper cleanup.

Prerequisites to Exploit

• A resource must have been released without clearing sensitive data.
• Access to the reused resource or its remnants.

Vulnerable Code

def release_resource(resource):
    # Release the resource but do not clear sensitive data
    del resource

This code releases a resource without clearing any sensitive information it may contain, leaving it accessible for reuse.

Secure Code

def release_resource_securely(resource):
    # Clear sensitive data before releasing the resource
    resource.clear_sensitive_data()
    del resource

The secure version ensures that all sensitive data is cleared or overwritten before the resource is released.

Business Impact of Sensitive Information in Resource Not Removed Before Reuse

Confidentiality: Exposes sensitive application data to unauthorized access, leading to potential breaches and loss of confidential information.

• Financial consequences due to data theft.
• Compliance issues with regulations like GDPR and HIPAA.
• Damage to reputation from publicized security incidents.

Sensitive Information in Resource Not Removed Before Reuse Attack Scenario

1. An attacker identifies a resource that has been released without proper cleanup.
2. The attacker accesses the residual sensitive data left behind after resource release.
3. Confidential information is compromised due to lack of proper cleanup mechanisms.

How to Detect Sensitive Information in Resource Not Removed Before Reuse

Manual Testing

• Review code for instances where resources are released without clearing sensitive data.
• Verify that all sensitive information is properly cleared before releasing a resource.

Automated Scanners (SAST / DAST)

Static analysis tools can identify patterns of resource release without proper cleanup, while dynamic testing can simulate attacks to check if residual data remains accessible.

PenScan Detection

PenScan’s automated scanners such as ZAP and Wapiti actively detect instances where sensitive information is not cleared before releasing resources for reuse.

False Positive Guidance

A false positive may occur if a resource is released but the remaining data is not actually sensitive or accessible to unauthorized users. Ensure that detected patterns are reviewed in context to confirm true vulnerabilities.

How to Fix Sensitive Information in Resource Not Removed Before Reuse

• Clear or overwrite sensitive information before releasing resources for reuse.
• Implement proper cleanup mechanisms during critical state transitions.

Framework-Specific Fixes for Sensitive Information in Resource Not Removed Before Reuse

Python/Django

def release_resource_securely(resource):
    # Clear sensitive data before releasing the resource
    resource.clear_sensitive_data()
    del resource

This code ensures that all sensitive information is cleared or overwritten before the resource is released, preventing unauthorized access.

How to Ask AI to Check Your Code for Sensitive Information in Resource Not Removed Before Reuse

Sensitive Information in Resource Not Removed Before Reuse Best Practices Checklist

✅ Clear or overwrite sensitive information before releasing resources for reuse.

✅ Implement proper cleanup mechanisms during critical state transitions.

✅ Verify that all sensitive data is properly cleared before resource release.

Sensitive Information in Resource Not Removed Before Reuse FAQ

How does sensitive information get left behind before resource reuse?

During critical state transitions, developers often forget to clear or overwrite the data in resources such as memory or files before making them available for reuse.

What are the consequences of not removing sensitive information before resource reuse?

This can lead to unauthorized access to application data and potential exposure of confidential information.

How do I detect Sensitive Information in Resource Not Removed Before Reuse vulnerabilities in my codebase?

Use static analysis tools like ZAP or Wapiti, which can identify instances where sensitive data is not cleared before resource reuse.

What are some best practices for preventing this vulnerability?

Overwrite information with fixed patterns (like all zeros) during critical state transitions and ensure proper cleanup of resources when they are released.

How does Sensitive Information in Resource Not Removed Before Reuse differ from other CWEs like Incomplete Cleanup or Improper Removal of Sensitive Information?

This vulnerability specifically focuses on the failure to remove sensitive information before reusing a resource, while others may cover broader cleanup issues.

Can you provide an example of vulnerable code for this issue?

Vulnerable code might release memory without clearing it first, leaving sensitive data accessible until the next allocation.

What are some common false positives when detecting Sensitive Information in Resource Not Removed Before Reuse?

False positives may occur if a resource is cleared but not immediately reused or if the data left behind is not actually sensitive.

Vulnerabilities Related to Sensitive Information in Resource Not Removed Before Reuse

References

• MITRE - CWE-226
• CAPEC-37
• NVD - NIST.gov

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 Sensitive Information in Resource Not Removed Before Reuse and other risks before an attacker does.