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ESA-2013-039: RSA BSAFE® SSL-J Multiple Vulnerabilities
EMC Identifier: ESA-2013-039
CVE Identifier: CVE-2011-3389, CVE-2013-0169
Severity Rating: CVSS v2 Base Score: Refer NVD (http://nvd.nist.gov/) for individual scores for each CVE
All versions of RSA BSAFE SSL-J except for 6.0.1 and 5.1.2
RSA BSAFE SSL-J 6.0.1 and 5.1.2 (newly released)
RSA BSAFE SSL-J 6.0.1 and 5.1.2 contain updates designed to prevent BEAST attacks (CVE-2011-3389) and SSL/TLS Plaintext Recovery (aka Lucky Thirteen) attacks (CVE-2013-0169).
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 important.
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.
Researchers have discovered a weakness in the handling of CBC cipher suites in SSL, TLS and DTLS. The “Lucky Thirteen” attack exploits timing differences arising during MAC processing. Vulnerable implementations do not properly consider timing side-channel attacks on a MAC check requirement during the processing of malformed CBC padding, which allows remote attackers to conduct distinguishing attacks and plaintext-recovery attacks via statistical analysis of timing data for crafted packets, aka the "Lucky Thirteen" issue.
Details of this attack can be found at: http://www.isg.rhul.ac.uk/tls/TLStiming.pdf
RSA recommends that customers on RSA BSAFE SSL-J 5.1.x or lower upgrade to RSA BSAFE SSL-J 5.1.2. RSA recommends that customers on RSA BSAFE SSL-J 6.0 upgrade to RSA BSAFE SSL-J 6.0.1.
To address BEAST, RSA introduce a new feature called first block splitting to RSA BSAFE SSL-J 6.0.1 and 5.1.2. First block splitting is designed to prevent 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 own. For RSA BSAFE SSL-J 6.0.1 and 5.1.2, first block splitting is engineered to be enabled by default for vulnerable cipher suites, making the application secure by default. If required, the application can disable first block splitting by setting the system property jsse.enableCBCProtection:
• Using the following Java code:
• On the Java command line, passing the following argument:
For more information about setting security properties, see section System and Security Properties in the RSA BSAFE SSL-J Developer Guide.
The best way to help prevent the BEAST 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.
To address Lucky Thirteen, RSA BSAFE SSL-J 6.0.1 and 5.1.2 contain a patch that is designed to help ensure that MAC checking is time invariant in servers.
Customers can also protect against the Lucky Thirteen attack by disabling CBC mode cipher suites on clients and servers. Cipher suites that use RC4 and, if TLS 1.2 is available, AES-GCM can be used.
To request your upgrade of the software, please call your local support telephone number (contact phone numbers are available at http://www.rsa.com/node.aspx?id=1356 ) for most expedient service. You may also request your software upgrade online at http://www.rsa.com/go/form_ins.asp .
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 link.
For an explanation of Severity Ratings, refer to the Knowledge Base Article, “Security Advisories Severity Rating” at https://knowledge.rsasecurity.com/scolcms/knowledge.aspx?solution=a46604. 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 More Information:
For more information about RSA products, visit the RSA web site at http://www.rsa.com.
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 tab.
General Customer Support Information:
RSA SecurCare Online:
RSA has a defined End of Primary Support policy associated with all major versions. Please refer to the link below for additional details. http://www.rsa.com/node.aspx?id=2575
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 liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if RSA or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
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