Date: Fri, 19 Oct 2001 12:16:32 -0400 (EDT)
From: EnGarde Secure Linux <[email protected]>
To: [email protected], [email protected]Subject: [ESA-20011019-02] kernel: Local DoS and root compromise
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| EnGarde Secure Linux Security Advisory October 19, 2001 |
| http://www.engardelinux.org/ ESA-20011019-02 |
| |
| Package: kernel |
| Summary: Local DoS and root compromise |
+------------------------------------------------------------------------+
EnGarde Secure Linux is a secure distribution of Linux that features
improved access control, host and network intrusion detection, Web
based secure remote management, complete e-commerce using AllCommerce,
and integrated open source security tools.
OVERVIEW
- --------
There are two vulnerabilities in the kernel which can allow a local
attacker to either obtain root privileges or lock the machine up for
an arbitrary amount of time.
DETAIL
- ------
There are two vulnerabilities in the version of the kernel which
shipped with EnGarde v1.0.1:
1) There is another local root exploit using the kernel's ptrace
capabilities.
2) The kernel can be forced to remain in path_walk() while
traversing a very deep tree of symbolic links for an arbitrary
amount of time, resulting in a local DoS attack.
Both vulnerabilities were discovered by Nergal ([email protected]).
A note from Nergal's advisory:
"In order for this flaw to be exploitable, /usr/bin/newgrp must be
setuid root and world-executable. Additionally, newgrp, when run
with no arguments, should not prompt for password. This conditions
are satisfied in case of most popular Linux distributions (but not
Openwall GNU/*/Linux)."
Please note that EnGarde Secure Linux does not ship with the 'newgrp'
utility, nor does it ship with any other setuid/setgid executables
which can be used to exploit this bug. Thus, EnGarde Secure Linux is
not vulnerable to the ptrace flaw (item #1 above).
Both vulnerabilies are very serious and all users are recommended to
upgrade immediately using the special SOLUTION in this advisory.
SOLUTION
- --------
All users should upgrade to the most recent version, as outlined in
this advisory.
Please note that kernel upgrades are not available through Guardian
Digital Secure Update. Please follow the steps outlined below to
upgrade your system manually. Updates can be obtained from:
ftp://ftp.engardelinux.org/pub/engarde/stable/updates/http://ftp.engardelinux.org/pub/engarde/stable/updates/
Please read and understand this entire section before you attempt to
upgrade the kernel.
Initial Steps
-------------
1) Verify the machine is either:
a) booted into a "standard" kernel; or
b) LIDS is disabled (/sbin/lidsadm -S -- -LIDS_GLOBAL)
2) Determine which kernels you currently have installed:
# rpm -qa --qf "%{NAME}\n" | grep kernel
3) Download the new kernels that match what you have installed
(based on step 2) from the "UPDATED PACKAGES" section of this
advisory.
Installation Steps
------------------
4) Install the new packages. The packages will automagically
update /etc/lilo.conf by commenting out any old EnGarde images
and replacing them with the new ones:
# rpm -i <kernel 1> <kernel 2> ...
5) Re-run LILO. If you see any errors then open /etc/lilo.conf in
your favorite text editor and make the appropriate changes:
# /sbin/lilo
Final Steps
-----------
6) If you did not see any LILO errors then your new kernel is now
installed and your machine is ready to be rebooted:
# reboot
UPDATED PACKAGES
- ----------------
These updated packages are for EnGarde Secure Linux 1.0.1 (Finestra).
Source Packages:
SRPMS/kernel-2.2.19-1.0.20.src.rpm
MD5 Sum: 6a58f06ed68b1d7d967f523712ee8835
Binary Packages:
i386/kernel-2.2.19-1.0.20.i386.rpm
MD5 Sum: 3704b6ced3c76c02c52238768cdeb1f3
i386/kernel-lids-mods-2.2.19-1.0.20.i386.rpm
MD5 Sum: f4140c01e414e52204a4bab8ac600fa7
i386/kernel-smp-lids-mods-2.2.19-1.0.20.i386.rpm
MD5 Sum: d02eb3e039cc37f15c7e6e56ece2d35a
i386/kernel-smp-mods-2.2.19-1.0.20.i386.rpm
MD5 Sum: dd89db42a52786e3aeaf17deab647df4
i686/kernel-2.2.19-1.0.20.i686.rpm
MD5 Sum: 0854c91dd5d178e44655d836da5d2fd3
i686/kernel-lids-mods-2.2.19-1.0.20.i686.rpm
MD5 Sum: 98823cfce2f4e4d8c7f10372e7fc6971
i686/kernel-smp-lids-mods-2.2.19-1.0.20.i686.rpm
MD5 Sum: 502b174927b2361eebd58e93422cbb25
i686/kernel-smp-mods-2.2.19-1.0.20.i686.rpm
MD5 Sum: e38e6b160c5d91fb64b02744b845b0b2
REFERENCES
- ----------
Guardian Digital's public key:
http://ftp.engardelinux.org/pub/engarde/ENGARDE-GPG-KEY
Credit for the discovery of this bug goes to:
Rafal Wojtczuk <[email protected]>
Official Web Site of the Linux Kernel:
http://www.kernel.org/
Security Contact: [email protected]
EnGarde Advisories: http://www.engardelinux.org/advisories.html
- --------------------------------------------------------------------------
$Id: ESA-20011019-02-kernel,v 1.3 2001/10/18 20:26:35 rwm Exp $
- --------------------------------------------------------------------------
Author: Ryan W. Maple, <[email protected]>
Copyright 2001, Guardian Digital, Inc.
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