EGI CSIRT:Alerts/kernel-2013-03-18

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EGI CSIRT ADVISORY [EGI-ADV-20130318]

Title:       Linux kernel ptrace vulnerability (CVE-2013-0871) [EGI-ADV-20130318]
Date:        2013-03-18
Updated:     2013-03-19

URL:         https://wiki.egi.eu/wiki/EGI_CSIRT:Alerts/kernel-2013-03-18


Update Summary
==============

 + 2013-03-19: The exploit code has been enhanced so as to work reliably not
               only on virtual machines, but also on actual hardware.


Introduction
============

Recently a vulnerability in the Linux kernel's ptrace() syscall was discovered.
This issue allows for local privilege escalation, but was believed to be hard to
exploit.  At the end of last week, Immunity Inc. have claimed that they have
exploit code that reliably works on both virtual machines and actual hardware.
The exploit code is only available to customers of Immunity.  The vulnerability
has been assigned CVE-2013-0871.


Details
=======

A race condition in the ptrace() syscall request handling code allows an
attacker to escalate her privileges when a process being debugged is sent a
SIGKILL signal.  The race condition appears to be very hard to win reliably, but
it now appears that under certain circumstances reliable exploitation can be
achieved.  At this time, it is unclear whether Immunity's exploit code works
only for 64-bit systems or for 32-bit systems as well, but in any case, they
have announced before that it is their intention to port the exploit to 32-bit
systems.


Risk Category
=============

This issue has been assessed as HIGH risk by the EGI CSIRT.  If the working
exploit code becomes publicly available, the risk assessment is expected to be
raised to CRITICAL.


Affected Software
=================

 + All Linux kernels in the 3.X series up to and including version 3.7.4, unless
   patched against this issue.

 + At least the most recent kernels in the 2.6.X Linux kernel series, unless
   patched against this issue.  Exactly how far back this issue goes is not
   clear at this moment.


Mitigation
==========

We strongly advise not to try to work around the problem but to upgrade the
kernel instead.


Component Installation information
==================================

For many distributions, patched kernel packages are available.  Refer to your
distro's information channels.


Recommendations
===============

It is recommended that all sites upgrade their systems to use patched kernels as
quickly as possible.  For RHEL-5-based systems, this means upgrading to at least
kernel version 2.6.18-348.3.1, and for RHEL-6-based systems, upgrading to at
least version 2.6.32-358.0.1.


References
==========

 + Mitre: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-0871
 + NIST NVD: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-0871
 + OSS-Sec: http://marc.info/?s=CVE-2013-0871&l=oss-security
 + Debian: https://security-tracker.debian.org/tracker/CVE-2013-0871
 + Scientific Linux 5: http://listserv.fnal.gov/scripts/wa.exe?A2=ind1303&L=scientific-linux-errata&T=0&P=4000
 + Scientific Linux 6: http://listserv.fnal.gov/scripts/wa.exe?A2=ind1303&L=scientific-linux-errata&T=0&P=4513
 + Scientific Linux CERN 5: http://linux.web.cern.ch/linux/updates/updates-slc5.shtml#20130314
 + Scientific Linux CERN 6: http://linux.web.cern.ch/linux/updates/updates-slc6.shtml#20130314
 + Red Hat: https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2013-0871
 + Red Hat EL5: https://rhn.redhat.com/errata/RHSA-2013-0621.html
 + Red Hat EL6: https://rhn.redhat.com/errata/RHSA-2013-0567.html
 + Ubuntu: http://people.canonical.com/~ubuntu-security/cve/CVE-2013-0871