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

Medium Nessus Plugin ID 94437

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. This plugin requires report paranoia as 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.

See Also

https://sweet32.info

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

Plugin Details

Severity: Medium

ID: 94437

File Name: ssl_64bitblock_supported_ciphers.nasl

Version: $Revision: 1.7 $

Type: remote

Family: General

Published: 2016/11/01

Modified: 2017/12/08

Dependencies: 21643

Risk Information

Risk Factor: Medium

CVSSv2

Base Score: 5

Temporal Score: 4.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N

Temporal Vector: CVSS2#E:F/RL:ND/RC:ND

CVSSv3

Base Score: 5.3

Temporal Score: 5.1

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Temporal Vector: CVSS:3.0/E:F/RL:X/RC:X

Vulnerability Information

Required KB Items: SSL/Supported, Settings/ParanoidReport

Exploit Available: true

Exploit Ease: Exploits are available

Vulnerability Publication Date: 2016/08/24

Reference Information

CVE: CVE-2016-2183, CVE-2016-6329

BID: 92630, 92631