Date: Mon, 9 Apr 2001 06:31:22 -0500
Reply-To: Progeny Security Team <security@PROGENY.COM>
From: Progeny Security Team <security@PROGENY.COM>
Subject: PROGENY-SA-2001-01: execve()/ptrace() exploit in Linux kernels
prior to 2.2.19
PROGENY LINUX SYSTEMS -- SECURITY ADVISORY PROGENY-SA-2001-01
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Topic: execve()/ptrace() exploit in Linux kernels prior to
2.2.19
Category: kernel
Module: kernel-image-2.2.*
Announced: 2001-04-04
Credits: Wojciech Purczynski <wp@elzabsoft.pl>
BUGTRAQ <BUGTRAQ@securityfocus.com>
Solar Designer <solar@openwall.com>
Affects: Progeny Debian (Linux kernels prior to 2.2.19)
Debian GNU/Linux (Linux kernels prior to 2.2.19)
Vendor-Status: New Version Released (kernel 2.2.19)
Corrected: 2001-04-02
Progeny Only: NO
$Id: PROGENY-SA-2001-01,v 1.8 2001/04/09 08:38:10 csg Exp $
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SYNOPSIS
Linux kernels before 2.2.19 are vulnerable to a local root exploit.
PROBLEM DESCRIPTION
This vulnerability exploits a race condition in the 2.2.x Linux kernel
within the execve() system call.
By predicting the child-process sleep() within execve(), an attacker
can use ptrace() or similar mechanisms to subvert control of the child
process. If the child process is setuid, the attacker can cause the
child process to execute arbitrary code at an elevated privilege.
There are also other known lesser security issues with Linux kernels prior
to 2.2.19 which have been noted as fixed in the solution listed below.
Details can be found in the Security Updates section at:
http://www.linux.org.uk/VERSION/relnotes.2219.html
IMPACT
Local users can use available exploits to gain root privileges.
SOLUTION
Upgrade to Linux kernel 2.2.19. You may use Progeny's kernel-image-2.2.19
package, version 1.81, for convenience.
WORKAROUND
No known workaround exists for this vulnerability.
UPDATING VIA APT-GET
1. Ensure that your /etc/apt/sources.list file has a URI for Progeny's
update repository:
deb http://archive.progeny.com/progeny/updates newton/
2. Update your cache of available packages for apt(8).
Example:
# apt-get update
3. Using apt(8), install the new kernel package. apt(8) will download
the update, verify it's integrity with md5, and then install the
package on your system with dpkg(8).
Example:
# apt-get install kernel-image-2.2.19
4. Since this update installs a new kernel, the security fixes cannot
take effect until you reboot the system. When convenient, restart
your system to start using the new kernel.
Example:
# shutdown -r now
UPDATING VIA DPKG
1. Using your preferred FTP/HTTP client to retrieve the following
updated files from Progeny's update archive at:
http://archive.progeny.com/progeny/updates/newton/
Filename MD5 Checksum
------------------------------------ --------------------------------
kernel-image-2.2.19_1.81_i386.deb f72c383e22a064ec394cff50a84ab789
Example:
# wget http://archive.progeny.com/progeny/updates/newton/kernel-image-2.2.19_1.81_i386.deb
2. Use the md5sum command on the retrieved file to verify that it matches
the md5sum provided in this advisory:
Example:
# md5sum kernel-image-2.2.19_1.81_i386.deb
3. Then install the replacement package(s) using the dpkg command.
Example:
# dpkg --install kernel-image-2.2.19_1.81_i386.deb
4. Since this update installs a new kernel, the security fixes cannot
take effect until you reboot the system. When convenient, restart
your system to start using the new kernel.
Example:
# shutdown -r now
MORE INFORMATION
Linux kernels 2.4.0 and later are not affected by this problem.
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pub 1024D/F92D4D1F 2001-04-04 Progeny Security Team <security@progeny.com>
