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Configuring Transport Level Security

Given below are the various transport-level security configurations that are required for WSO2 products. See the following topics for instructions.

• Disabling weak ciphers
• Changing the server name in HTTP response headers

Disabling weak ciphers

A cipher is an algorithm for performing encryption or decryption. When you set the sslprotocol of your server to TLS, the TLS and the default ciphers get enabled without considering the strength of the ciphers. This is a security risk as weak ciphers, also known as EXPORT ciphers, can make your system vulnerable to attacks such as the Logjam attack on Diffie-Hellman key exchange. The Logjam attack is also called the Man-in-the-Middle attack. It downgrades your connection's encryption to a less-secured level (e.g., 512 bit) that can be decrypted with sufficient processing power.

To prevent these types of security attacks, it is encouraged to disable the weak ciphers. You can enable only the ciphers that you want the server to support in a comma-separated list in the ciphers attribute. Also, if you do not add this cipher attribute or keep it blank, the browser will support all the SSL ciphers by JSSE. This will enable the weak ciphers.

Disabling weak ciphers for the Tomcat transport

1. Open the <PRODUCT_HOME>/repository/conf/deployment.toml file.
2. Take a backup of the deployment.toml file and stop the Carbon server.

3. Add the following configuration to the deployment.toml file by adding the list of ciphers that you want your server to support as follows: ciphers=",".

   [transport.https.sslHostConfig.properties]
   ciphers="TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384, TLS_DHE_DSS_WITH_AES_256_GCM_SHA384, TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256, TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256, TLS_DHE_DSS_WITH_AES_128_GCM_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384, TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384, TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384, TLS_DHE_DSS_WITH_AES_256_CBC_SHA256, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDH_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_DSS_WITH_AES_256_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256, TLS_DHE_DSS_WITH_AES_128_CBC_SHA256, TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA, TLS_ECDH_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_DSS_WITH_AES_128_CBC_SHA, TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS_ECDH_ECDSA_WITH_RC4_128_SHA, TLS_ECDH_RSA_WITH_RC4_128_SHA, TLS_EMPTY_RENEGOTIATION_INFO_SCSVF"

   See the list of supported cipher suites.

4. Start the server.

5. To verify that the configurations are all set correctly, download and run the TestSSLServer.jar.

   $ java -jar TestSSLServer.jar localhost 9443

   Note

   Note the following when you run TestSSLServer.jar :

   • The "Supported cipher suites" section in the output does not contain any EXPORT ciphers.

   • When you use the supported cipher suites listed here, the BEAST attack status will be shown as vulnerable. Note that this is a client-side vulnerability caused by the TLSv1 protocol. You can make the BEAST status protected by removing TLSv1, which will make clients with TLSv1 unusable. Therefore, it is recommended tofixed this from the client side.

Info

From Firefox 39.0 onwards, the browser does not allow to access Web sites that support DHE with keys less than 1023 bits (not just DHE_EXPORT). 768/1024 bits are considered to be too small and vulnerable to attacks if the hacker has enough computing resources.

Tip

• To use AES-256, the Java JCE Unlimited Strength Jurisdiction Policy files need to be installed. Download them from http://www.oracle.com/technetwork/java/javase/downloads/index.html, if your java installation does not have it installed.

Configuring Passthrough transport-level ciphers and TLS versions

1. To enable preferred ciphers, add the configuration given below to the <PRODUCT_HOME>/repository/conf/deployment.toml file.

   Format

   [transport.passthru_https.listener.parameters]
   PreferredCiphers = "<CIPHER_LIST>"

   Example

   [transport.passthru_https.listener.parameters]
   PreferredCiphers = "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384"

2. To enable HTTP protocols (TLS versions), add the configurations given below to the <PRODUCT_HOME>/repository/conf/deployment.toml file.

   Format

   [transport.passthru_https.listener.parameters]
   HttpsProtocols = "<TLS_VERSION_LIST>"

   Example

   [transport.passthru_https.listener.parameters]
   HttpsProtocols = "TLSv1,TLSv1.1,TLSv1.2,TLSv1.3"

Changing the server name in HTTP response headers

By default, all WSO2 products pass "WSO2 Carbon Server" as the server value in HTTP headers when sending HTTP responses. This means that information about the WSO2 product stack will be exposed through HTTP responses. It is recommended to change this by configuring the server name in the deployment.toml file.

1. Open the <PRODUCT_HOME>/repository/conf/deployment.toml file.

2. Add a new server name using the server property (under the relevant Tomcat connector configuration):

   [transport.https.properties]
   server="WSO2 Carbon Server"
   
   [transport.http.properties]
   server="WSO2 Carbon Server"

Info

See the Security Guidelines for Production Deployment for the full list of security-related recommendations for WSO2 products.

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