The program can potentially fail to release a file handle.
The program can potentially fail to release a file handle.
Resource leaks have at least two common causes:
- Error conditions and other exceptional circumstances.
- Confusion over which part of the program is responsible for releasing the resource.
Most unreleased resource issues result in general software reliability problems, but if an attacker can intentionally trigger a resource leak, the attacker might be able to launch a denial of service attack by depleting the resource pool.
Example 1: The following method never closes the file handle it opens. The finalize()
method for ZipFile
eventually calls close()
, but there is no guarantee as to how long it will take before the finalize()
method will be invoked. In a busy environment, this can result in the JVM using up all of its file handles.
public void printZipContents(String fName)
throws ZipException, IOException, SecurityException, IllegalStateException, NoSuchElementException
{
ZipFile zf = new ZipFile(fName);
Enumeration<ZipEntry> e = zf.entries();
while (e.hasMoreElements()) {
printFileInfo(e.nextElement());
}
}
public void printZipContents(String fName)
throws ZipException, IOException, SecurityException, IllegalStateException, NoSuchElementException
{
ZipFile zf = new ZipFile(fName);
Enumeration<ZipEntry> e = zf.entries();
while (e.hasMoreElements()) {
printFileInfo(e.nextElement());
}
}
[1] Standards Mapping - OWASP Top 10 2004 - (OWASP 2004) A9 Application Denial of Service
[2] Standards Mapping - Security Technical Implementation Guide Version 3 - (STIG 3) APP6080 CAT II
[3] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 404
[4] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 - (PCI 1.1) Requirement 6.5.9
[5] Standards Mapping - SANS Top 25 2009 - (SANS 2009) Risky Resource Management - CWE ID 404