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

This script is Copyright (C) 2016-2017 Tenable Network Security, Inc.


Synopsis :

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

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.

See also :

https://sweet32.info
https://www.openssl.org/blog/blog/2016/08/24/sweet32/

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.

Risk factor :

Medium / CVSS Base Score : 5.0
(CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N)
CVSS Temporal Score : 4.8
(CVSS2#E:F/RL:ND/RC:ND)
Public Exploit Available : true

Family: General

Nessus Plugin ID: 94437 ()

Bugtraq ID: 92630
92631

CVE ID: CVE-2016-2183
CVE-2016-6329

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