SWEET 32 vulnerability

Document ID : KB000006725
Last Modified Date : 14/02/2018
Show Technical Document Details
Issue:

SWEET 32 vulnerability 

Nessus scan on Production servers has identified High severity vulnerability. "The remote host supports the use of a block cipher with 64-bit blocks in one or more cipher suites. It is, therefore, affected by a vulnerability, known as SWEET32, due to the use of weak 64-bit block ciphers. A man-in-the-middle attacker who has sufficient resources can exploit this vulnerability, via a 'birthday' attack, to detect a collision that leaks the XOR between the fixed secret and a known plaintext, allowing the disclosure of the secret text, such as secure HTTPS cookies, and possibly resulting in the hijacking of an authenticated session. 

Plugin Name: SSL 64-bit Block Size Cipher Suites Supported (SWEET32) 

Synopsis: The remote service supports the use of 64-bit block ciphers. 

Environment:
All DevTest environments.
Cause:

Proof-of-concepts have shown that attackers can recover authentication cookies from an HTTPS session in as little as 30 hours. 

Note that the ability to send a large number of requests over the same TLS connection between the client and server is an important requirement for carrying out this attack. If the number of requests allowed for a single connection were limited, this would mitigate the vulnerability. However, Nessus has not checked for such a mitigation."

Resolution:

Modifying the java.security file in DevTest_Home/jre/lib/security folder as below resolved the issue. 

Change jdk.tls.disabledAlgorithms=SSLv3, RC4, DH keySize < 768

to  jdk.tls.disabledAlgorithms=SSLv3, RC4, DESede, DH keySize < 768

 

This should be read as "disable SSLv3, all RC4 ciphers, all Triple-DES ciphers and any Diffie-Hellman ciphers with a keysize of less than 768 bits."

DESede -is an alias for Triple-DES within the Sun JCE.

Additional Information:

Oracle's JDK and JRE java Cryptographic Algorithms documentation is available at https://www.java.com/en/configure_crypto.html .