block-wise chosen-plaintext attack against SSL/TLS (BEAST)
CVE: CVE-2011-3389
Component: HTTPS
Severity: Moderate
Release date: 2011-09-10T00:00:00+00:00

The SSL protocol, as used in certain configurations in Microsoft Windows and Microsoft Internet Explorer, Mozilla Firefox, Google Chrome, Opera, and other products, encrypts data by using CBC mode with chained initialization vectors, which allows man-in-the-middle attackers to obtain plaintext HTTP headers via a blockwise chosen-boundary attack (BCBA) on an HTTPS session, in conjunction with JavaScript code that uses (1) the HTML5 WebSocket API, (2) the Java URLConnection API, or (3) the Silverlight WebClient API, aka a "BEAST" attack.

Statement: Red Hat is aware of, and tracking, the Rizzo/Duong chosen plain text attack on SSL/TLS 1.0, also known as "BEAST". This issue has been assigned CVE-2011-3389. This attack uses web browser extensions to exploit a weakness in SSL/TLS cipher-block chaining (CBC), allowing a man-in-the-middle attacker to recover certain session information, such as cookie data, from what should be a secure connection.

The research shows two ways that an attacker could mount an attack. In both cases the attacker needs access to the data stream from the web browser to the server while a user visits a malicious website using a browser. The attacker may then be able to determine a portion of the data the browser sends to the server by making a large number of requests over a period of time. This data could include information such as an authentication cookie.

The first method of attack involves using WebSockets. Currently, Red Hat does not ship any products that allow an attack using WebSockets to be successful. We are planning to update Firefox to version 7, which contains protections in the WebSocket code that prevents this particular attack from being effective. 

The second method of attack involves using a malicious Java applet. In order for the attack to be successful, the attacker would need to circumvent the Same Origin Policy (SOP) controls in Java. The researchers claim to have found a flaw in the Java SOP and we will issue updates to correct this flaw as suitable fixes are available.

We are in contact with various upstream projects regarding this attack. As a precautionary measure, we plan to update the Network Security Services (NSS), GnuTLS, and OpenSSL packages as suitable fixes are available.

We will continue to track this issue and take any appropriate actions as needed.

This statement and any updates to it is available at:
https://bugzilla.redhat.com/show_bug.cgi?id=737506

Remediation:
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259
Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/knowledge/articles/11258
Before applying this update, make sure all previously released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the
Red Hat Network to apply this update are available at
https://access.redhat.com/site/articles/11258