Unreleased Resource: Sockets

ABSTRACT

程序可能無法釋放某個套接字。

EXPLANATION

程序可能無法成功釋放某一個套接字。


資源泄露至少有兩種常見的原因：

－ 錯誤狀況及其他異常情況。

－ 未明確程序的哪一部份負責釋放資源。

大部分 Unreleased Resource 問題只會導致一般的軟件可靠性問題，但如果攻擊者能夠故意觸發資源泄漏，該攻擊者就有可能通過耗盡資源池的方式發起 denial of service 攻擊。

例 1：下面的方法絕不會關閉它所打開的套接字。在繁忙的環境中，這會導致 JVM 用盡它所有的套接字。

private void echoSocket(String host, int port) throws UnknownHostException, SocketException, IOException
{
Socket sock = new Socket(host, port);
BufferedReader reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));

while ((String socketData = reader.readLine()) != null) {
System.out.println(socketData);
  }
}

private void echoSocket(String host, int port) throws UnknownHostException, SocketException, IOException
{
Socket sock = new Socket(host, port);
BufferedReader reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));

while ((String socketData = reader.readLine()) != null) {
System.out.println(socketData);
  }
sock.close();
}

REFERENCES

[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 - Security Technical Implementation Guide Version 3.4 - (STIG 3.4) APP6080 CAT II

[4] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 404

[5] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 - (PCI 1.1) Requirement 6.5.9

[6] Standards Mapping - SANS Top 25 2009 - (SANS 2009) Risky Resource Management - CWE ID 404