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             AUSCERT External Security Bulletin Redistribution

       ESA-2012-032: RSA BSAFE® Micro Edition Suite Security Update
            for BEAST (Browser Exploit Against SSL/TLS) attacks
                             12 September 2012


        AusCERT Security Bulletin Summary

Product:          RSA BSAFE Micro Edition Suite
Publisher:        EMC
Operating System: Windows
                  Red Hat
Impact/Access:    Access Privileged Data -- Remote with User Interaction
Resolution:       Patch/Upgrade
CVE Names:        CVE-2011-3389  

Reference:        ESB-2012.0866

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ESA-2012-032: RSA BSAFE® Micro Edition Suite Security Update for BEAST 
(Browser Exploit Against SSL/TLS) attacks

EMC Identifier: ESA-2012-032
CVE Identifier: CVE-2011-3389

Severity Rating: CVSS v2 Base Score: 4.3 (AV:N/AC:M/Au:N/C:P/I:N/A:N)

Affected Products:
All versions of RSA BSAFE Micro Edition Suite prior to 4.0, all platforms

Unaffected Products:
RSA BSAFE Micro Edition Suite 4.0 and higher


RSA BSAFE Micro Edition Suite contains updates designed to prevent BEAST 
attacks (CVE-2011-3389)


There is a known vulnerability in SSLv3 and TLS v1.0 to do with how the 
Initialization Vector (IV) is generated. For symmetric key algorithms in CBC 
mode, the IV for the first record is generated using keys and secrets set 
during the SSL or TLS handshake. All subsequent records are encrypted using 
the ciphertext block from the previous record as the IV. With symmetric key 
encryption in CBC mode, plain text encrypted with the same IV and key 
generates the same cipher text, which is why having a variable IV is 

The BEAST exploit uses this SSLv3 and TLS v1.0 vulnerability by allowing an 
attacker to observe the last ciphertext block, which is the IV, then replace 
this with an IV of their choice, inject some of their own plain text data, 
and when this new IV is used to encrypt the data, the attacker can guess the 
plain text data one byte at a time.


The best way to help prevent this attack is to use TLS v1.1 or higher. The 
vulnerability to do with IV generation was fixed in TLS v1.1 (released in 
2006) so implementations using only TLS v1.1 or v1.2 are engineered to be 
secure against the BEAST exploit. However, support for these higher level 
protocols is limited to a smaller number of applications, so supporting only 
TLS v1.1 or v1.2 might cause interoperability issues.

A second solution is to limit the negotiated cipher suites to exclude those 
that do not require symmetric key algorithms in CBC mode. However, this 
substantially restricts the number of cipher suites that can be negotiated. 
That is, only cipher suites with NULL encryption or cipher suites with 
streaming encryption algorithms (the RC4 algorithm) could be negotiated, 
which might result in reduced security.

For customers who cannot or should not implement either of these two methods, 
RSA BSAFE Micro Edition Suite 4.0 introduces a new feature called first block 
splitting. First block splitting prevents the BEAST exploit by introducing 
unknown data into the encryption scheme prior to the attackers inserted plain 
text data. This is done as follows: 

1. The first plain text block to be encrypted is split into two blocks. 
The first block contains the first byte of the data, the second block contains 
the rest.
2. A MAC is generated from the one byte of data, the MAC key, and an 
increasing counter. This MAC is included in the first block.
3. The one byte of data, along with the MAC, is encrypted and becomes 
the IV for the next block. Because the IV is now essentially random data, it 
is impossible for an attacker to predict it and replace it with one of their 
To implement first block splitting in RSA BSAFE Micro Edition Suite 4.0, 
either for an SSL context or SSL object, call R_SSL_CTX_set_options_by_type() 
or R_SSL_set_options_by_type() respectively, with the SSL_OP_TYPE_SECURITY 
option type and the SSL_OP_SPLIT_FIRST_FRAGMENT identifier.

For more information about these functions and identifiers, see the RSA BSAFE 
Micro Edition Suite API Reference Guide.

Severity Rating:

For an explanation of Severity Ratings, refer to the Knowledge Base Article, 
Security Advisories Severity Rating at 
RSA recommends all customers take into account both the base score and any 
relevant temporal and environmental scores which may impact the potential 
severity associated with particular security vulnerability.

Obtaining Documentation:

To obtain RSA documentation, log on to RSA SecurCare Online at 
https://knowledge.rsasecurity.com and click Products in the top navigation 
menu. Select the specific product whose documentation you want to obtain. 
Scroll to the section for the product version that you want and click the set 

Obtaining More Information:

For more information about RSA BSAFE, visit the RSA web site at 

Getting Support and Service:

For customers with current maintenance contracts, contact your local RSA 
Customer Support center with any additional questions regarding this RSA 
SecurCare Note. For contact telephone numbers or e-mail addresses, log on to 
RSA SecurCare Online at https://knowledge.rsasecurity.com, click Help & 
Contact, and then click the Contact Us - Phone tab or the Contact Us - Email 

General Customer Support Information:


RSA SecurCare Online:


EOPS Policy:

RSA has a defined End of Primary Support policy associated with all major 
versions. Please refer to the link below for additional details. 

SecurCare Online Security Advisories

RSA, The Security Division of EMC, distributes SCOL Security Advisories in 
order to bring to the attention of users of the affected RSA products 
important security information. RSA recommends that all users determine the 
applicability of this information to their individual situations and take 
appropriate action. The information set forth herein is provided "as is" 
without warranty of any kind. RSA disclaim all warranties, either express or 
implied, including the warranties of merchantability, fitness for a particular 
purpose, title and non-infringement. In no event shall RSA or its suppliers be 
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consequential, loss of business profits or special damages, even if RSA or its 
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incidental damages so the foregoing limitation may not apply.

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EMC Product Security Response Center



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