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Linux Advisory Watch: February 24th 2006 Print E-mail
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Source: Contributors - Posted by Benjamin D. Thomas   
Linux Advisory Watch This week, advisories were released for heimdal, GnuPG, pdfkit, tutos, netpbm, compat-db, kdebase, gndb-kernel, cman-kernel, dlm-kernel, GFS-kernel, BomberClone, GnuPG, OpenSSH, GPdf, bluez-hcidump, libtiff, kernel, MySQL, tar, metamail, and CASA. The distributors include Debian, Fedora, Gentoo, Mandriva, and SuSE.

EnGarde Secure Linux: Why not give it a try?

EnGarde Secure Linux is a Linux server distribution that is geared toward providing a open source platform that is highly secure by default as well as easy to administer. EnGarde Secure Linux includes a select group of open source packages configured to provide maximum security for tasks such as serving dynamic websites, high availability mail transport, network intrusion detection, and more. The Community edition of EnGarde Secure Linux is completely free and open source, and online security and application updates are also freely available with GDSN registration.

Writing Behind a Buffer
Angelo Rosiello

In this paper we are going to describe a kind of vulnerability that is known in the literature but also poor documented. In fact, the problem that is going to be analyzed can be reduced to a memory adjacent overwriting attack but usually it is obtained exploiting the last null byte of a buffer, hence we are going to show that the same result is still possible writing behind a buffer, under certain conditions. To fully understand the subject of this article it's necessary to describe the memory organization1 of running processes, then the memory adjacent overwrite attack, concluding with our analysis.

Memory Organization

A process can be defined as a running program, thus the operating system has loaded its instructions into memory and has allocated different areas of memory to manage its execution. The address space of a running process can be divided into five segments[1,2]:

* Code Segment: this segment contains the executable code of the program.

* Data and BSS Segment: both sectors are dedicated to the global variables and are allocated during the compile time. To be clear, the sector BSS contains not initialized data while data segment is reserved for static data.

* Stack Segment: local variables are allocated in this segment. It is particular useful for storing cotext and for function parameters. The stack memory grows downward.

* Heap Segment: this segment represents all the rest of memory ofthe process. The heap memory grows upward and is allocated dynamically.

The memory adjacent overwrite attack, exploits the memory allocated into the stack for automatic variables to produce a buffer overflow[6] and to gain the control of the process execution flow.

Memory Adjacent Overwrite Attack Last years were released some articles[4,5] about exploiting non-terminated adjacent memory space. The problem exists when the last null byte, terminating a buffer, is overwritten and another buffer precedes it.

In fact, when a buffer is declared it is finished into the stack with a null byte to separate it from the rest of the stack. To stay clear let's bring an example written in C where we are going to use two buffers.

Read Full Paper Feature Extras:

EnGarde Secure Community 3.0.4 Released - Guardian Digital is happy to announce the release of EnGarde Secure Community 3.0.4 (Version 3.0, Release 4). This release includes several bug fixes and feature enhancements to the Guardian Digital WebTool and the SELinux policy, and several new packages available for installation.

Linux File & Directory Permissions Mistakes - One common mistake Linux administrators make is having file and directory permissions that are far too liberal and allow access beyond that which is needed for proper system operations. A full explanation of unix file permissions is beyond the scope of this article, so I'll assume you are familiar with the usage of such tools as chmod, chown, and chgrp. If you'd like a refresher, one is available right here on

Introduction: Buffer Overflow Vulnerabilities - 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.

Take advantage of our Linux Security discussion list! This mailing list is for general security-related questions and comments. To subscribe send an e-mail to with "subscribe" as the subject.

Thank you for reading the 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 heimdal packages fix several vulnerabilities
  16th, February, 2006

Updated package.
  Debian: New GnuPG packages fix invalid success return
  17th, February, 2006

Updated package.
  Debian: New pdfkit.framework packages fix several vulnerabilities
  17th, February, 2006

Updated package.
  Debian: New tutos packages fix multiple vulnerabilities
  22nd, February, 2006

Joxean Koret discovered several security problems in tutos, a web-based team organization software. The Common Vulnerabilities and Exposures Project identifies the following problems...
  Fedora Core 4 Update: netpbm-10.31-1.FC4.2
  16th, February, 2006

Updated package.
  Fedora Core 4 Update: compat-db-4.2.52-2.FC4
  17th, February, 2006

updated package.
  Fedora Core 4 Update: gnupg-
  17th, February, 2006

The GNU Privacy Guard provides encryption and signing for messages and arbitrary files, and implements the OpenPGP standard as described by IETF RFC2440.
  Fedora Core 4 Update: kdebase-3.5.1-0.3.fc4
  17th, February, 2006

Updated package.
  Fedora Core 4 Update: gnbd-kernel-
  22nd, February, 2006

Updated GFS & Cluster Suite packages for the latest kernel (kernel-2.6.15-1.1831_FC4).
  Fedora Core 4 Update: cman-kernel-
  22nd, February, 2006

Updated GFS & Cluster Suite packages for the latest kernel (kernel-2.6.15-1.1831_FC4).
  Fedora Core 4 Update: dlm-kernel-
  22nd, February, 2006

Updated GFS & Cluster Suite packages for the latest kernel (kernel-2.6.15-1.1831_FC4).
  Fedora Core 4 Update: GFS-kernel-
  22nd, February, 2006

Updated GFS & Cluster Suite packages for the latest kernel (kernel-2.6.15-1.1831_FC4).
  Gentoo: libtasn1, GNU TLS Security flaw in DER decoding
  16th, February, 2006

A flaw in the parsing of Distinguished Encoding Rules (DER) has been discovered in libtasn1, potentially resulting in the execution of arbitrary code.
  Gentoo: BomberClone Remote execution of arbitrary code
  16th, February, 2006

BomberClone is vulnerable to a buffer overflow which may lead to remote execution of arbitrary code.
  Gentoo: GnuPG Incorrect signature verification
  18th, February, 2006

Applications relying on GnuPG to authenticate digital signatures may incorrectly believe a signature has been verified.
  Gentoo: OpenSSH, Dropbear Insecure use of system() call
  20th, February, 2006

A flaw in OpenSSH and Dropbear allows local users to elevate their privileges via scp.
  Gentoo: GPdf Heap overflows in included Xpdf code
  21st, February, 2006

GPdf includes vulnerable Xpdf code to handle PDF files, making it vulnerable to the execution of arbitrary code.
  Mandriva: Updated kernel packages fix multiple vulnerabilities
  17th, February, 2006

A number of vulnerabilities were discovered and corrected in the Linux 2.6 kernel: The udp_v6_get_port function in udp.c, when running IPv6, allows local users to cause a Denial of Service (infinite loop and crash) (CVE-2005-2973).
  Mandriva: Updated bluez-hcidump packages fix buffer overflow vulnerability
  17th, February, 2006

Buffer overflow in l2cap.c in hcidump allows remote attackers to cause a denial of service (crash) through a wireless Bluetooth connection via a malformed Logical Link Control and Adaptation Protocol (L2CAP) packet.
  Mandriva: Updated libtiff packages fix vulnerability
  17th, February, 2006

Stack-based buffer overflow in libTIFF before 3.7.2 allows remote attackers to execute arbitrary code via a TIFF file with a malformed BitsPerSample tag. Although some of the previous updates appear to already catch this issue, this update adds some additional checks.
  Mandriva: Updated gnupg packages fix signature file verification vulnerability
  17th, February, 2006

Tavis Ormandy discovered it is possible to make gpg incorrectly return success when verifying an invalid signature file. The updated packages have been patched to address this issue.
  Mandriva: Updated kernel packages fix multiple vulnerabilities
  21st, February, 2006

A number of vulnerabilities have been discovered and corrected in the Linux 2.4 kernel: A numeric casting discrepancy in sdla_xfer could allow a local user to read portions of kernel memory via a large len argument (CVE-2004-2607).
  Mandriva: Updated MySQL packages fix temporary file vulnerability
  22nd, February, 2006

Eric Romang discovered a temporary file vulnerability in the mysql_install_db script provided with MySQL. This vulnerability only affects versions of MySQL 4.1.x prior to 4.1.12. The updated packages have been patched to address this issue.
  Mandriva: Updated tar packages fix vulnerability
  22nd, February, 2006

Gnu tar versions 1.14 and above have a buffer overflow vulnerability and some other issues including...
  Mandriva: Updated metamail packages fix vulnerability
  23rd, February, 2006

Ulf Harnhammar discovered a buffer overflow vulnerability in the way that metamail handles certain mail messages. An attacker could create a carefully-crafted message that, when parsed via metamail, could execute arbitrary code with the privileges of the user running metamail.
    Red Hat
  RedHat: Low: tar security update
  21st, February, 2006

An updated tar package that fixes a path traversal flaw is now available. This update has been rated as having low security impact by the Red Hat Security Response Team.
  RedHat: Important: metamail security update
  21st, February, 2006

An updated metamail package that fixes a buffer overflow vulnerability for Red Hat Enterprise Linux 2.1 is now available. This update has been rated as having important security impact by the Red Hat Security Response Team.
  SuSE: gpg,liby2util signature checking
  20th, February, 2006

With certain handcraftable signatures GPG was returning a 0 (valid signature) when used on command-line with option --verify. This only affects GPG version 1.4.x, so it only affects SUSE Linux 9.3 and 10.0. Other SUSE Linux versions are not affected.
  SuSE: CASA remote code execution
  22nd, February, 2006

Updated package.

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