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By pathologically modifying a clients ClientHello message with fragmentation, it's possible to cause the server to negotiate TLS 1.0 instead of a higher version, even if both client and server support a higher protocol version.
External References: https://www.openssl.org/news/secadv_20140806.txt
Description below: OpenSSL TLS protocol downgrade attack (CVE-2014-3511) ===================================================== A flaw in the OpenSSL SSL/TLS server code causes the server to negotiate TLS 1.0 instead of higher protocol versions when the ClientHello message is badly fragmented. This allows a man-in-the-middle attacker to force a downgrade to TLS 1.0 even if both the server and the client support a higher protocol version, by modifying the client's TLS records. OpenSSL 1.0.1 SSL/TLS server users should upgrade to 1.0.1i. Thanks to David Benjamin and Adam Langley (Google) for discovering and researching this issue. This issue was reported to OpenSSL on 21st July 2014. The fix was developed by David Benjamin.
Upstream commit: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=280b1f1ad12131defcd986676a8fc9717aaa601b
Support for TLS versions 1.1 and 1.2 was added upstream in OpenSSL version 1.0.1. Red Hat Enterprise Linux 6 before 6.5 provided openssl packages based on version 1.0.0. Hence Red Hat Enterprise Linux 6 packages prior to update RHBA-2013:1585 released as part of Red Hat Enterprise Linux 6.5, as well as packages in Red Hat Enterprise Linux 5 and earlier, were not affected as TLS 1.0 is the highest supported protocol version.
Created attachment 924724 [details] CVE-2014-3511 patch CVE-2014-3511 patch for CentOS 6.5.
Created openssl tracking bugs for this issue: Affects: fedora-all [bug 1127704]
Created mingw-openssl tracking bugs for this issue: Affects: fedora-all [bug 1127705]
Created mingw-openssl tracking bugs for this issue: Affects: epel-7 [bug 1127709]
openssl-1.0.1e-39.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.
openssl-1.0.1e-39.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.
IssueDescription: A flaw was found in the way OpenSSL handled fragmented handshake packets. A man-in-the-middle attacker could use this flaw to force a TLS/SSL server using OpenSSL to use TLS 1.0, even if both the client and the server supported newer protocol versions.
This issue has been addressed in following products: Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Via RHSA-2014:1052 https://rhn.redhat.com/errata/RHSA-2014-1052.html
This issue has been addressed in following products: Red Hat Storage 2.1 Via RHSA-2014:1054 https://rhn.redhat.com/errata/RHSA-2014-1054.html
This issue has been addressed in the following products: RHEV-H and Agents for RHEL-6 Via RHSA-2015:0126 https://rhn.redhat.com/errata/RHSA-2015-0126.html
This issue has been addressed in the following products: RHEV Manager version 3.5 Via RHSA-2015:0197 https://rhn.redhat.com/errata/RHSA-2015-0197.html