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:     2013-03-18

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


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

Recently a vulnerability in the Linux kernel's ptrace() syscall 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 works on 64-bit virtual machines, and that they are
working on both 32-bit and non-VM versions.  This exploit code is only available to
customer 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.


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