RHSA-2012:0070 - Security Advisory

トピック

Updated ruby packages that fix two security issues are now available for
Red Hat Enterprise Linux 4 and 5.

The Red Hat Security Response Team has rated this update as having moderate
security impact. Common Vulnerability Scoring System (CVSS) base scores,
which give detailed severity ratings, are available for each vulnerability
from the CVE links in the References section.

説明

Ruby is an extensible, interpreted, object-oriented, scripting language. It
has features to process text files and to do system management tasks.

A denial of service flaw was found in the implementation of associative
arrays (hashes) in Ruby. An attacker able to supply a large number of
inputs to a Ruby application (such as HTTP POST request parameters sent to
a web application) that are used as keys when inserting data into an array
could trigger multiple hash function collisions, making array operations
take an excessive amount of CPU time. To mitigate this issue, randomization
has been added to the hash function to reduce the chance of an attacker
successfully causing intentional collisions. (CVE-2011-4815)

It was found that Ruby did not reinitialize the PRNG (pseudorandom number
generator) after forking a child process. This could eventually lead to the
PRNG returning the same result twice. An attacker keeping track of the
values returned by one child process could use this flaw to predict the
values the PRNG would return in other child processes (as long as the
parent process persisted). (CVE-2011-3009)

Red Hat would like to thank oCERT for reporting CVE-2011-4815. oCERT
acknowledges Julian Walde and Alexander Klink as the original reporters of
CVE-2011-4815.

All users of ruby are advised to upgrade to these updated packages, which
contain backported patches to resolve these issues.

解決策

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

影響を受ける製品

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Server 4 x86_64
• Red Hat Enterprise Linux Server 4 ia64
• Red Hat Enterprise Linux Server 4 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Workstation 4 x86_64
• Red Hat Enterprise Linux Workstation 4 ia64
• Red Hat Enterprise Linux Workstation 4 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux Desktop 4 x86_64
• Red Hat Enterprise Linux Desktop 4 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems 4 s390x
• Red Hat Enterprise Linux for IBM z Systems 4 s390
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux for Power, big endian 4 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

修正

• BZ - 722415 - CVE-2011-2686 CVE-2011-2705 CVE-2011-3009 ruby: Properly initialize the random number generator when forking new process
• BZ - 750564 - CVE-2011-4815 ruby: hash table collisions CPU usage DoS (oCERT-2011-003)

CVE

• CVE-2011-3009
• CVE-2011-4815

参考資料

• https://access.redhat.com/security/updates/classification/#moderate
• http://www.ocert.org/advisories/ocert-2011-003.html