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The attack requires cooperation between an outer component (which can intercept traffic) and an inner component which runs on the attacked machine and is able to inject arbitrary data (chosen by the attacker) within the SSL tunnel, along with the piece of data which is to be decrypted. The general view among most people in the crypto and security communities ...

First things first: don't panic. Don't do anything rash, and take time to think. The slides which have appeared today describe new results on bias in RC4. RC4 generates a key-dependent stream of pseudo-random bytes, which is then XORed with the data to encrypt (decryption is identical). It was known that the output of RC4 was slightly biased, i.e. some byte ...

Theory of the BEAST Attack SSL uses various combinations of public and symmetric key algorithms. (OpenSSL's list) When the symmetric algorithm is a block algorithm (as opposed to stream), cipher block chaining is used -- the previous block is part of the input to the new block. The problems we're seeing right now are implementation-based, and they've been ...

In IIS 7 (and 7.5), there are two things to do: Navigate to: Start > 'gpedit.msc' > Computer Configuration > Admin Templates > Network > SSL Configuration Settings > SSL Cipher Suite Order (in right pane, double click to open). There, copy and paste the following (entries are separated by a single comma, make sure there's no line wrapping): ...

One way to mitigate BEAST is to do nothing. It so happens that though the vulnerability used in BEAST is still there, exploiting it is rather difficult. It requires the ability to do cross-domain requests, with a high level of control on the data which is sent in the request; in particular, it needs "binary" data. Duong and Rizzo did not find a way to map ...

Background. To learn more about how to mitigate the BEAST attack, I recommend reading the following two blog posts: Rizzo/Duong BEAST Countermeasures and Mitigating the BEAST attack on TLS. You'll quickly learn that there are no really great solutions. What to scan for. Right now, the only known server-side mitigation is for the server to force use of RC4 ...

GCM is recommended; it is even approved by NIST. However, AEAD ciphers are supported in TLS only since TLS 1.2; see section 6.2.3.3, which is new, when compared to TLS 1.1. The actual GCM-able cipher suites are defined in RFC 5288. Note that TLS 1.2 (and, for that matter, TLS 1.1 too) is immune to BEAST-like attacks when using CBC. Therefore you will have a ...

OpenSSL has a mitigation for BEAST which has been enabled by default since 0.9.6d, so as long as your OpenSSL version is this version or later and you haven't set SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS there is no need to restrict ciphers or disable TLS 1.0.

Edit (2012/09/23): Ask and ye shall receive. TestSSLServer is a simple command-line tool which I wrote this week-end; it obtains from a given SSL/TLS server the list of supported cipher suites, protocol versions and support of TLS-level Deflate. It then gives a summary of the encryption strength and the vulnerability to BEAST and CRIME attacks. It is written ...

I don't think anyone knows of any way to exploit BEAST, on any of those modern browsers, so as far as anyone knows, those browsers are probably pretty safe against BEAST-like attacks. On the other hand, the underlying weakness is still present, which leaves some room for concern about the possibility that someone might find a new way to exploit that ...

I just posted an update to IIS Crypto which is a free tool that sets the schannel registry keys and puts RC4 at the top of the SSL cipher suite order with a single click. This mitigates the BEAST attack on Windows Server 2008 and 2012.

Until the security hole is closed both ends (web server and browser software) it will be hard to prevent. Unfortunately because the current exploit targets cookies you have minimal control over it client-side. The only exception is to change your encryption ciphers and block or reorder CBC ciphers to the least preferable so it has the least likelihood of ...

Move rc4-based cipher suites to the top of the list; the attack seems to be related to CBC, and rc4-sha is not vulnerable if that is the case. Update - we've released a white paper here detailing how to make the changes. Available here. To clarify, protocol version won't help you here due to practical considerations - servers cannot disable TLS1.0/SSL3 at ...

I am not sure what you mean by not supported. Currently the following browsers support TLS 1.1 and 1.2: Chrome - v22, released Sept 2012 Internet Explorer - v10, released April 2011, but it looks like it only supports TLS 1.2 from Feb 2013 Opera - v12.10, released Nov 2012 Safari - v6, released July 2012 So of the big browsers, only Firefox is lagging.

The main reason why there is little movement is that the "breaks" are not practical enough to show up on radar. BEAST does not work anymore. Firstly, it requires a way for client code in the browser (hostile Java or hostile Javascript) to emit cross-domain requests with a high level of control at the bit level; the two known ways to do that (a draft ...

1) This is not exploited through XSS, but through a client visiting a malicious site. The targeted website does not need to exhibit any flaws at all. Details: http://vnhacker.blogspot.com/2011/09/beast.html 2) RC4 in WEP was vulnerable because of an implementation flaw. AES in TLS 1.0 / CBC mode... exactly the same kind of problem. They're still strong ...

Without knowing the internal workings on the patch I can only guess, but... Both IE and IIS support versions of TLS that are not vulnerable to BEAST, e.g. TLS 1.1 and 1.2, but these versions are not on by default. Also, it's dependent on the cipher suite used in the connection for 1.0. The patch could do a number of things like turn the versions on by ...

this is based on some online searches alone, with no detailed anlaysis, but from what I gather, it's more of a client-side vulnerability than a server one. Of course the vulnerability is when the communication between client and server is attacked, but the fix should be primarily on the client. The primary reason, as I understand it, is because the client ...

I have written a command-line tool called TestSSLServer which can be used for that job. The tool makes a lot of aborted handshakes with the server (it sends the ClientHello and receives the ServerHello; then it closes the connection). First, it establishes the list of cipher suites supported by the server, by sending a full list of many suites, then ...

How does one disable CBC 'mode' on IIS6? You disable all ciphers that have CBC in their name. http://support.microsoft.com/default.aspx?scid=kb;EN-US;245030 describes how; https://www.nartac.com/Products/IISCrypto/Default.aspx provides a tool to do it for you. Also, from that second website: Note - Windows Server 2003 does not support the ...

You can't solve this without your browser vendor's assistance. Communicate with your browser vendor to indicate that you would like to see support for TLS 1.2. (There is probably a bug report already in their bug tracker; probably you can just vote for it, and monitor it, to see when a new version of the browser is available with support for TLS 1.2.) ...

The simplest way to mitigate BEAST is to do nothing at all. BEAST is a client attack. Servers can "protect" clients by enforcing the use of RC4-based cipher suites even if the client states that it prefers some CBC cipher suites. However, all recent Web browser versions include workarounds which make them immune to BEAST, namely the 1/n-1 split; and the ...

Since the patch has been released some time ago, we can now have more information. The security bulletin is quite devoid of technical information, but some clues can be gathered from reading the KB article about known issues. The patch does, basically, two things: The patch activates TLS 1.1 support. This support was already included in Internet Explorer, ...

Previously, the attack was considered possible in principle but not a serious threat in practice. It was believed that the attack would require so much chosen plaintext that the attack was not a practical threat. In addition, in the web setting, there was no known way to get the victim's browser to encrypt the chosen plaintext with the necessary level of ...

For a web application, unless you know your clients are going to be using IE, then you should probably stick to RC4. For a non-web application just force the client to use TLS 1.1 or 1.2 and the problem goes away. There is a client side fix, and it is implemented in SChannel (used by IE), but only in the development version of NSS (used by Firefox and ...

from the way this exploit is supposed to work as a MitM from inside the browser attacking via blockwise-adaptive chosen-plaintext cryptanalysis..... the current and only solution (limited-security) I can think of (until Browsers & Servers are patched to work with newer versions... gonna take time) is Browsing all your secure sessions from an ...

There are two parts to SSL/TLS: ensuring the confidentiality and the integrity of the communication, and knowing who each participant is. Most of the issues related to SSL have to do with the second part, which is rather more complicated. You can read some explanations on this topic in the question when is it safe to click through an SSL warning message? ...

Not really an answer to your whole question, but RC4 is not inherently insecure. It was just the way WEP used it. According to SecurityNow! episode 11: Steve: Well, and, for example, it uses an extremely good cipher technology called RC4. That's an RSA proprietary cipher which is very good for encrypting as long as you use it correctly. And that's ...

If you are using TLS 1.0 with a CBC-based ciphersuite, you are potentially vulnerable to the BEAST attack. Cryptographically the TLS_RSA_WITH_3DES_EDE_CBC_SHA ciphersuite is still fine and in TLS 1.1 and TLS 1.2 you will have no issues. Protocol-wise with HTTPS it is not so fine with regards to BEAST in TLS 1.0. (although the AES-based ciphersuites are ...

A possible fix is to totally disable all non-RC4 cipher suites. This will break connections from clients who have elected not to use RC4 (possibly, these would be quite rare), but at least it will guarantee that if a connection is made at all, then it will use RC4, which is immune to BEAST. In true SSL/TLS, the server is supposed to follow the client's ...