-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 +------------------------------------------------------------------------+ | 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 (nergalat_private). 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 <nergalat_private> Official Web Site of the Linux Kernel: http://www.kernel.org/ Security Contact: securityat_private 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, <ryanat_private> Copyright 2001, Guardian Digital, Inc. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE70FHoHD5cqd57fu0RAsUFAKCRfsVCyQClt/+icF5mSK3lztpSeACfZyRv z9MnxfOxqI/Wqcg3gtD4rJ0= =ob5F -----END PGP SIGNATURE-----
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