SSLv3 Padding Oracle On Downgraded Legacy Encryption Vulnerability (POODLE)

Medium Nessus Plugin ID 78479

Synopsis

It is possible to obtain sensitive information from the remote host with SSL/TLS-enabled services.

Description

The remote host is affected by a man-in-the-middle (MitM) information disclosure vulnerability known as POODLE. The vulnerability is due to the way SSL 3.0 handles padding bytes when decrypting messages encrypted using block ciphers in cipher block chaining (CBC) mode.
MitM attackers can decrypt a selected byte of a cipher text in as few as 256 tries if they are able to force a victim application to repeatedly send the same data over newly created SSL 3.0 connections.

As long as a client and service both support SSLv3, a connection can be 'rolled back' to SSLv3, even if TLSv1 or newer is supported by the client and service.

The TLS Fallback SCSV mechanism prevents 'version rollback' attacks without impacting legacy clients; however, it can only protect connections when the client and service support the mechanism. Sites that cannot disable SSLv3 immediately should enable this mechanism.

This is a vulnerability in the SSLv3 specification, not in any particular SSL implementation. Disabling SSLv3 is the only way to completely mitigate the vulnerability.

Solution

Disable SSLv3.

Services that must support SSLv3 should enable the TLS Fallback SCSV mechanism until SSLv3 can be disabled.

See Also

https://www.imperialviolet.org/2014/10/14/poodle.html

https://www.openssl.org/~bodo/ssl-poodle.pdf

https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00

Plugin Details

Severity: Medium

ID: 78479

File Name: ssl_poodle.nasl

Version: 1.20

Type: remote

Family: General

Published: 2014/10/15

Updated: 2019/07/22

Dependencies: 21643, 56984

Risk Information

Risk Factor: Medium

CVSS Score Source: CVE-2014-3566

CVSS v2.0

Base Score: 4.3

Temporal Score: 3.2

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

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3.0

Base Score: 6.8

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

Vulnerability Information

Required KB Items: SSL/Supported

Exploit Available: false

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 2014/10/14

Reference Information

CVE: CVE-2014-3566

BID: 70574

CERT: 577193