Objective
Nessus Output
Description
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.
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.
Solution
Reconfigure the affected application, if possible, to avoid use of all 64-bit block ciphers. Alternatively, place limitations on the number of requests that are allowed to be processed over the same TLS connection to mitigate this vulnerability.
Output
List of 64-bit block cipher suites supported by the remote server :
Medium Strength Ciphers (> 64-bit and < 112-bit key)
TLSv1
DES-CBC3-SHA Kx=RSA Au=RSA Enc=3DES-CBC(168) Mac=SHA1
The fields above are :
{OpenSSL ciphername}
Kx={key exchange}
Au={authentication}
Enc={symmetric encryption method}
Mac={message authentication code}
{export flag}
Solution
References
