Bug 908445 (CVE-2013-1623) - CVE-2013-1623 yaSSL: TLS CBC padding timing attack
Summary: CVE-2013-1623 yaSSL: TLS CBC padding timing attack
Alias: CVE-2013-1623
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2013-02-06 17:36 UTC by Vincent Danen
Modified: 2021-02-17 08:04 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2013-02-06 17:40:51 UTC

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Description Vincent Danen 2013-02-06 17:36:06 UTC
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:


Comment 1 Vincent Danen 2013-02-06 17:40:51 UTC
MySQL in Red Hat Enterprise Linux and Fedora are built against OpenSSL, not the embedded yaSSL.


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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