CVE-2013-1619: Medium severity GNU GnuTLS vulnerability
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:
http://www.isg.rhul.ac.uk/tls/TLStiming.pdf
External References:
http://www.isg.rhul.ac.uk/tls/ http://www.gnutls.org/security.html#GNUTLS-SA-2013-1
Patches:
2.12.x: https://gitorious.org/gnutls/gnutls/commit/458c67cf98740e7b12404f6c30e0d5317d56fd30 https://gitorious.org/gnutls/gnutls/commit/93b7fcfa3297a9123630704668b2946f602b910e
3.0.x: https://gitorious.org/gnutls/gnutls/commit/8dc2822966f64dd9cf7dde9c7aacd80d49d3ffe5
3.2.x / master: https://gitorious.org/gnutls/gnutls/commit/328ee22c1b3951e060c7124c7cb1cee592c59bc0
Other sources
The TLS implementation in GnuTLS before 2.12.23, 3.0.x before 3.0.28, and 3.1.x before 3.1.7 does not properly consider timing side-channel attacks on a noncompliant MAC check operation 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, a related issue to CVE-2013-0169.
Affected Software
Remediation
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2013-1619?
CVE-2013-1619 has a medium severity rating, indicating it could allow a Man-in-the-Middle attacker to exploit TLS/DTLS connections.
How do I fix CVE-2013-1619?
To fix CVE-2013-1619, update to GnuTLS versions 2.12.23, 3.0.28, or later versions that have patched this vulnerability.
Which software is affected by CVE-2013-1619?
CVE-2013-1619 affects multiple versions of GnuTLS, particularly those before 2.12.23 and 3.0.28.
What type of attack can exploit vulnerabilities in CVE-2013-1619?
CVE-2013-1619 can be exploited through Man-in-the-Middle attacks that recover plaintext data from TLS/DTLS connections.
Is there a workaround for CVE-2013-1619 until I can update?
There is no permanent workaround for CVE-2013-1619 other than upgrading to a secure version of GnuTLS.