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Bug 908445 - (CVE-2013-1623) CVE-2013-1623 yaSSL: TLS CBC padding timing attack
CVE-2013-1623 yaSSL: TLS CBC padding timing attack
Status: CLOSED NOTABUG
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
impact=moderate,public=20130204,repor...
: Security
Depends On:
Blocks:
  Show dependency treegraph
 
Reported: 2013-02-06 12:36 EST by Vincent Danen
Modified: 2013-02-06 13:49 EST (History)
3 users (show)

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Doc Type: Bug Fix
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Last Closed: 2013-02-06 12:40:51 EST
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RHEL 7.3 requirements from Atomic Host:


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Description Vincent Danen 2013-02-06 12:36:06 EST
A flaw in how TLS/DTLS, when CBC-mode encryption is used, communicates was reported.  This vulnerability can allow for a Man-in-the-Middle attacker to recover plaintext from a TLS/DTLS connection, when CBC-mode encryption is used.

This flaw is in the TLS specification, and not a bug in a specific implementation (as such, it affects nearly all implementations).  As such, it affects all TLS and DTLS implementations that are compliant with TLS 1.1 or 1.2, or with DTLS 1.0 or 1.2.  It also applies to implementations of SSL 3.0 and TLS 1.0 that incorporate countermeasures to deal with previous padding oracle attacks.  All TLS/DTLS ciphersuites that include CBC-mode encryption are potentially vulnerable.

The paper indicates that with OpenSSL, a full plaintext recovery attack is possible, and with GnuTLS, a partial plaintext recovery is possible (recovering up to 4 bits of the last byte in any block of plaintext).

To perform a successful attack, when TLS is used, a large number of TLS sessions are required (target plaintext must be sent repeatedly in the same position in the plaintext stream across the sessions).  For DTLS, a successful attack can be carried out in a single session.  The attacker must also be located close to the machine being attacked.

Further details are noted in the paper.

External References:

http://www.isg.rhul.ac.uk/tls/
http://www.isg.rhul.ac.uk/tls/TLStiming.pdf
Comment 1 Vincent Danen 2013-02-06 12:40:51 EST
MySQL in Red Hat Enterprise Linux and Fedora are built against OpenSSL, not the embedded yaSSL.


Statement:

Not vulnerable. This issue did not affect the versions of mysql as shipped with Red Hat Enterprise Linux 5 or 6. The packages use OpenSSL and not yaSSL.

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