Instances from the class javax.net.ssl.SSLSocket must be created instead of normal Sockets when transferring sensitive objects over communication channels. The class SSLSockets provides security protocols such as SSL or TLS to ensure that the channel is not open to eavesdropping and malicious tampering.
The principal protections included in SSLSockets that are not provided by the Socket class are: [[Java API]]
- Integrity Protection. SSL protects against modification of messages by an active wiretapper.
- Authentication. In most modes, SSL provides peer authentication. Servers are usually authenticated, and clients may be authenticated as requested by servers.
- Confidentiality (Privacy Protection). In most modes, SSL encrypts data being sent between client and server. This protects the confidentiality of data, so that passive wiretappers won't see sensitive data such as financial information or personal information of many kinds.
It is also important to use SSL for secure RMI communications because RMI depends on object serialization and serialized data must be safeguarded in transit. Gong et al. [[Gong 03]] describe how to secure RMI communications using SSLSockets.
Noncompliant Code Example
This example shows the use of regular sockets for a server application that does not protect sensitive information in transit. The insecure code for the corresponding client application follows the server's code.
class EchoServer {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(10007);
Socket socket = serverSocket.accept();
PrintWriter out = new PrintWriter(socket.getOutputStream(),true);
BufferedReader in = new BufferedReader(
new InputStreamReader( socket.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println (inputLine);
out.println(inputLine);
}
out.close();
in.close();
socket.close();
}
catch (Exception e) { /*Handle exception*/ }
}
}
class EchoClient {
public static void main(String[] args) {
try {
Socket socket = new Socket("localhost", 9999);
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(socket.getInputStream()));
BufferedReader stdIn = new BufferedReader(
new InputStreamReader(System.in));
String userInput;
while ((userInput = stdIn.readLine()) != null) {
out.println(userInput);
System.out.println(in.readLine());
}
out.close();
in.close();
stdIn.close();
socket.close();
}
catch (Exception e) { /*Handle exception*/ }
}
}
Compliant solution
This compliant solution makes use of SSLSockets to protect packets using the SSL and TLS security protocols.
class EchoServer {
public static void main(String[] args) {
try {
SSLServerSocketFactory sslserversocketfactory =
(SSLServerSocketFactory) SSLServerSocketFactory.getDefault();
SSLServerSocket sslserversocket =
(SSLServerSocket) sslserversocketfactory.createServerSocket(9999);
SSLSocket sslsocket = (SSLSocket) sslserversocket.accept();
PrintWriter out = new PrintWriter( sslsocket.getOutputStream(),true);
BufferedReader in = new BufferedReader(
new InputStreamReader( sslsocket.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println (inputLine);
out.println(inputLine);
}
out.close();
in.close();
sslsocket.close();
}
catch (Exception e) { /*Handle exception*/ }
}
}
class EchoClient {
public static void main(String[] args) {
try {
SSLSocketFactory sslsocketfactory =
(SSLSocketFactory) SSLSocketFactory.getDefault();
SSLSocket sslsocket =
(SSLSocket) sslsocketfactory.createSocket("localhost", 9999);
PrintWriter out = new PrintWriter(sslsocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(sslsocket.getInputStream()));
BufferedReader stdIn = new BufferedReader(
new InputStreamReader(System.in));
String userInput;
while ((userInput = stdIn.readLine()) != null) {
out.println(userInput);
System.out.println(in.readLine());
}
out.close();
in.close();
stdIn.close();
sslsocket.close();
}
catch (Exception e) { /*Handle exception*/ }
}
}
Note that a program that makes use of SSLSockets will block indefinitely if it tries to connect to a port that is not using SSL and, similarly, a program that does not use SSLSockets will block when trying to establish a connection through a port that uses SSL.
Risk assesment
Using plain sockets instead of SSLSockets means that the data's confidentiality and integrity is not protected.
Rule |
Severity |
Likelihood |
Remediation Cost |
Priority |
Level |
|---|---|---|---|---|---|
SEC09- J |
medium |
likely |
high |
P6 |
L2 |
Automated Detection
TODO
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Exceptions
EX1: Because of the mechanisms that SSLSockets provide to ensure the secure transfer of packets, significant performance overhead may result. If no sensitive information is being transmitted, or the channel is not prone to attacks, regular Sockets are sufficient.
References
[[API 06]]
[[Gong 03]] 11.3.3 "Securing RMI Communications"
[[Ware 08]]
[[MITRE 09]] CWE ID 311
"Failure to Encrypt Sensitive Data"
SEC08-J. Define custom security permissions for fine grained security 02. Platform Security (SEC) SEC10-J. Call the superclass's getPermissions method when writing a custom class loader