The product does not release or incorrectly releases a resource before it is made available for re-use.

What CVEs are caused by CWE-404?

510 recorded CVEs are attributed to CWE-404, including CVE-2018-8639, CVE-2018-8611, CVE-2018-8405. 5 are listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.

Is CWE-404 part of the OWASP Top 10?

CWE-404 maps to OWASP Top Ten 2004: Denial of Service (A9) in the OWASP security taxonomy.

How do you prevent CWE-404?

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

How is CWE-404 detected?

Automated Dynamic Analysis: This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

What are the consequences of CWE-404?

Exploiting CWE-404 can lead to: DoS: Resource Consumption (Other), Varies by Context, Read Application Data.

Is CWE-404 actively exploited?

Yes. 5 CWE-404 vulnerabilities are in CISA's KEV catalog of actively exploited flaws, out of 510 recorded CVEs.

CWE-404: Improper Resource Shutdown or Release

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

The following method never closes the new file handle. Given enough time, the Finalize() method for BufferReader should eventually call Close(), but there is no guarantee as to how long this action will take. In fact, there is no guarantee that Finalize() will ever be invoked. In a busy environment, the Operating System could use up all of the available file handles before the Close() function is called.

Vulnerable example

java

private void processFile(string fName)

Safe example

java

private void processFile(string fName)

The good code example simply adds an explicit call to the Close() function when the system is done using the file. Within a simple example such as this the problem is easy to see and fix. In a real system, the problem may be considerably more obscure.

This code attempts to open a connection to a database and catches any exceptions that may occur.

Vulnerable example

java

try {

If an exception occurs after establishing the database connection and before the same connection closes, the pool of database connections may become exhausted. If the number of available connections is exceeded, other users cannot access this resource, effectively denying access to the application.

Under normal conditions the following C# code executes a database query, processes the results returned by the database, and closes the allocated SqlConnection object. But if an exception occurs while executing the SQL or processing the results, the SqlConnection object is not closed. If this happens often enough, the database will run out of available cursors and not be able to execute any more SQL queries.

The following C function does not close the file handle it opens if an error occurs. If the process is long-lived, the process can run out of file handles.

Vulnerable example

int decodeFile(char* fName) {

In this example, the program does not use matching functions such as malloc/free, new/delete, and new[]/delete[] to allocate/deallocate the resource.

Vulnerable example

cpp

class A {

In this example, the program calls the delete[] function on non-heap memory.

Vulnerable example

cpp

class A{

CWE-404: Improper Resource Shutdown or Release

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Dynamic Analysis

Manual Dynamic Analysis

Automated Static Analysis

Code examples

Illustrative examples

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

References

Stay ahead of CWE-404

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Dynamic Analysis

Manual Dynamic Analysis

Automated Static Analysis

Code examples

Illustrative examples

Related weaknesses

Parent

Child

Peer

Can precede

Terminology & mappings

Mapped taxonomies

Attack patterns

Frequently asked questions

References

Stay ahead of CWE-404