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

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** WHITE information - Unlimited distribution allowed                       **
** see https://wiki.egi.eu/wiki/EGI_CSIRT:TLP for distribution restrictions **

EGI CSIRT ADVISORY [EGI-ADV-20130318]

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

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


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

Recently, a vulnerability in the Linux kernel's ptrace() syscall has been
discovered.  This issue allows for local privilege escalation, but is actually
hard to exploit.  At the end of last week, Immunity Inc. have claimed that they
have exploit code that works on 64-bit virtual machines, and that they are
working on both 32-bit and non-VM versions.  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
under certain circumstances this is facilitated.


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
==========

It is possible to disable the ptrace() syscall in a customized kernel.  However,
this is not trivial, and prevents debugging in general.  For further
information, see
  http://blog.ghedini.me/post/10240771002/kernel-module-to-disable-ptrace


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.


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 EL5: https://rhn.redhat.com/errata/RHSA-2013-0567.html
+ Ubuntu: http://people.canonical.com/~ubuntu-security/cve/CVE-2013-0871