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Date: Wed, 18 Dec 2019 10:16:02 -0800
From: Aaron Patterson <aaron.patterson@...il.com>
To: rubyonrails-security@...glegroups.com, oss-security@...ts.openwall.com,
	ruby-security-ann@...glegroups.com
Subject: [CVE-2019-16782] Possible Information Leak / Session Hijack
 Vulnerability in Rack

There is a possible information leak / session hijacking vulnerability
in Rack. This vulnerability has been assigned the CVE identifier
CVE-2019-16782.

Versions Affected:  All.
Not affected:       None.
Fixed Versions:     1.6.12, 2.0.8

There's a possible information leak / session hijack vulnerability in
Rack. Attackers may be able to find and hijack sessions by using timing
attacks targeting the session id. Session ids are usually stored and
indexed in a database that uses some kind of scheme for speeding up
lookups of that session id. By carefully measuring the amount of time it
takes to look up a session, an attacker may be able to find a valid
session id and hijack the session.

The session id itself may be generated randomly, but the way the session
is indexed by the backing store does not use a secure comparison.


Impact
------

The session id stored in a cookie is the same id that is used when
querying the backing session storage engine. Most storage mechanisms
(for example a database) use some sort of indexing in order to speed up
the lookup of that id. By carefully timing requests and session lookup
failures, an attacker may be able to perform a timing attack to
determine an existing session id and hijack that session.

Releases
--------

The 1.6.12 and 2.0.8 releases are available at the normal locations.

Workarounds
-----------

There are no known workarounds.

Patches
-------

To aid users who aren't able to upgrade immediately we have provided patches for
the two supported release series. They are in git-am format and consist of a
single changeset.

1-6-session-timing-attack.patch - Patch for 1.6 series
2-0-session-timing-attack.patch - Patch for 2.6 series

Credits
-------

Thanks Will Leinweber for reporting this!

-- 
Aaron Patterson
http://tenderlovemaking.com/

View attachment "1-6-session-timing-attack.patch" of type "text/plain" (17949 bytes)

View attachment "2-0-session-timing-attack.patch" of type "text/plain" (16516 bytes)

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)

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