Author: Benjamin D. Thomas
kernel, autofs, GnomeVFS, phpMyAdmin, shorewall, gtk, shareutils, gdk-buf, kdegraphics,
dhcp, and gaim. The distributors include Debian, Fedora, Gentoo, Mandrake, Red
Hat, and SuSE.Introduction: Buffer Overflow Vulnerabilities
By: Erica R. Thomas
Buffer overflows are a leading type of security vulnerability. This
paper explains what a buffer overflow is, how it can be exploited,
and what countermeasures can be taken to prevent the use of buffer
overflow vulnerabilities.
Buffer overflow vulnerabilities are one of the most common
vulnerabilities. These kinds of vulnerabilities are perfect for
remote access attacks because they give the attacker a great
opportunity to launch and execute their attack code on the target
computer. Broadly speaking, a buffer overflow attack occurs when
the attacker intentionally enters more data than a program was
written to handle. The data runs over and overflows the section
of memory that was set aside to accept it. The extra data
overwrites on top on another portion of memory that was meant
to hold something else, like part of the program’s instructions.
This allows an attacker to overwrite data that controls the
program and can takeover control of the program to execute the
attacker’s code instead of the program. Peikari and Chuvakin
point out that, “buffer overflows result from an inherent
weakness in the C++ programming language.” (Peikari and
Chuvakin, 2004) The problem is that C++ and other programming
languages (those derived from C++), do not automatically
perform bounds-checking when passing data. When variables
are passed, extra characters could be written past the
variable’s end. The overflow consequence could result in
the program crashing or allowing the attacker to execute
their own code on the target system.
In order to make sense of how a buffer is overflowed, one must
understand what a buffer is. A program contains code that
accesses variables stored in various locations in memory. When
a program is executed, a specific amount of memory is assigned
for each variable. The amount of memory is determined by the
type of data the variable is anticipated to hold. The memory
set aside is used to store information that the program needs
for its execution. According to Peikari and Chuvakin , “The
program stores the value of a variable in this memory space,
then pulls the value back out of memory when it’s needed.”
(Peikari and Chuvakin, 2004) A buffer is this virtual space.
Read Full Article:
http://www.linuxsecurity.com/content/view/118881/49/
LinuxSecurity.com
Feature Extras:Getting
to Know Linux Security: File Permissions – Welcome to the first
tutorial in the ‘Getting to Know Linux Security’ series. The topic explored
is Linux file permissions. It offers an easy to follow explanation of how
to read permissions, and how to set them using chmod. This guide is intended
for users new to Linux security, therefore very simple. If the feedback is
good, I’ll consider creating more complex guides for advanced users. Please
let us know what you think and how these can be improved.The
Tao of Network Security Monitoring: Beyond Intrusion Detection
– To be honest, this was one of the best books that I’ve read on network security.
Others books often dive so deeply into technical discussions, they fail to
provide any relevance to network engineers/administrators working in a corporate
environment. Budgets, deadlines, and flexibility are issues that we must all
address. The Tao of Network Security Monitoring is presented in such a way
that all of these are still relevant.Encrypting
Shell Scripts – Do you have scripts that contain sensitive information
like passwords and you pretty much depend on file permissions to keep it secure?
If so, then that type of security is good provided you keep your system secure
and some user doesn’t have a “ps -ef” loop running in an attempt to capture
that sensitive info (though some applications mask passwords in “ps” output).
Take advantage of our Linux Security discussion
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Thank you for reading the LinuxSecurity.com
weekly security newsletter. The purpose of this document is to provide our readers
with a quick summary of each week’s most relevant Linux security headline.
| Debian: New axel packages fix arbitrary code execution | ||
13th, April, 2005
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| Fedora Core 3 Update: gftp-2.0.18-0.FC3 | ||
7th, April, 2005
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| Fedora Core 2 Update: gftp-2.0.18-0.FC2 | ||
7th, April, 2005
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| Fedora Core 3 Update: wireless-tools-27-1.2.0.fc3 | ||
7th, April, 2005
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| Fedora Core 3 Update: glibc-2.3.5-0.fc3.1 | ||
7th, April, 2005
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| Fedora Core 3 Update: selinux-policy-targeted-1.17.30-2.94 | ||
8th, April, 2005
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| Fedora Core 3 Update: kernel-2.6.11-1.14_FC3 | ||
11th, April, 2005
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| Fedora Core 3 Update: selinux-policy-targeted-1.17.30-2.96 | ||
11th, April, 2005
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| Fedora Core 3 Update: autofs-4.1.3-114 | ||
12th, April, 2005
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| Fedora Core 3 Update: gcc-3.4.3-22.fc3 | ||
12th, April, 2005
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| Fedora Core 3 Update: gcc4-4.0.0-0.41.fc3 | ||
12th, April, 2005
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| Gentoo: GnomeVFS, libcdaudio CDDB response overflow | ||
8th, April, 2005
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| Gentoo: Smarty Template vulnerability | ||
10th, April, 2005
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| Gentoo: phpMyAdmin Cross-site scripting vulnerability | ||
11th, April, 2005
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| Gentoo: Axel Vulnerability in HTTP redirection handling | ||
12th, April, 2005
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| Mandrake: Updated shorewall packages | ||
7th, April, 2005
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| Mandrake: Updated gtk+2.0 packages fix | ||
7th, April, 2005
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| Mandrake: Updated sharutils packages | ||
7th, April, 2005
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| Mandrake: Updated gdk-pixbuf packages | ||
7th, April, 2005
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| RedHat: Moderate: kdegraphics security update | ||
12th, April, 2005
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| RedHat: Moderate: dhcp security update | ||
12th, April, 2005
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| RedHat: Important: gaim security update | ||
12th, April, 2005
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| SuSE: various KDE security problems | ||
11th, April, 2005
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