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Security Alert

Security Alert: Streamripper buffer overflow bug

Multiple buffer overflows involving HTTP header and playlist parsing have been discovered in streamripper (CVE-2007-4337, CVE-2008-4829).

For the stable distribution (etch), these problems have been fixed in version 1.61.27-1+etch1.

For the unstable distribution (sid) and the testing distribution (lenny), these problems have been fixed in version 1.63.5-2.

How do I fix this bug and update package?

Simply type the following two commands:
# apt-get update
# apt-get upgrade

Red Hat Enterprise Linux 5 IMPORTANT Security Update [ 4-Nov-2008 ]

Red Hat today released kernel updates to fix at least 15 security flaws in its core called Linux kernel. RHEL users can grab the latest updates from RHN website or by simply running yum update command. This update has been rated as having important security impact.
[click to continue…]

Debian Upgrade: GNU/Linux 4.0 Update 5 Available

The industry strength community driven enterprise grade Debian GNU/Linux version 4.0 stable update 5 has been released and available for immediate downloaded as well as updates via apt-get package manager. This update mainly adds corrections for security problems to the stable release, along with a few adjustment to serious problems. All users are advised to upgrade system.

Those who frequently install updates from security.debian.org won’t have to update many packages and most updates from security.debian.org are included in this update.

New CD and DVD images containing updated packages and the regular installation media accompanied with the package archive respectively will be available soon at the regular locations.

Miscellaneous Bugfixes

This stable update adds several binary updates for various architectures to packages whose version was not synchronised across all architectures. It also adds a few important corrections to the following packages:


    apache2Fix several vulnerabilities
    apache2-mpm-itkRebuild against apache2 and fix hanging processes on restart/shutdown
    blosxomFix XSS
    distFix insecure temp file usage
    fai-kernelsFix xfs corruption / Xen crash
    fetaFix insecure temp file usage
    git-coreSupport download of packs v2 through dumb transports
    gobyRebuild against net6
    irqbalanceFix segfault when /proc/interrupts contains an interrupt with a number of 256 or larger
    jumpnbumpFix insecure handling of /tmp
    libpam-pwdfileUse gcc instead of ld
    linux-2.6Fix xfs corruption / Xen crash
    myspellFix insecure temp file usage
    net6Fix object access after deallocation
    obbyRebuild against new net6
    postgresql-8.1Upstream bugfix release 8.1.13
    sobbyRebuild against new net6
    tracFix multiple vulnerabilities
    tzdataUpdates to several timezones and daylight saving times settings
    user-mode-linuxFix xfs corruption / Xen crash
    wdiffFix race condition related to temporary files

Debian Linux Security Updates

This revision adds the following security updates to the stable release. The Security Team has already released an advisory for each of these updates:

    Advisory IDPackageCorrection(s)

    DSA 1597mt-daapdFix several vulnerabilities (fixes for regression)
    DSA 1614iceweaselFix several vulnerabilities
    DSA 1615xulrunnerFix several vulnerabilities
    DSA 1616clamavFix denial of service
    DSA 1617refpolicyFix incompatible policy
    DSA 1618ruby1.9Fix several vulnerabilities
    DSA 1619python-dnsFix DNS response spoofing
    DSA 1620python2.5Fix several vulnerabilities
    DSA 1621icedoveFix several vulnerabilities
    DSA 1622newsxFix arbitrary code execution
    DSA 1623dnsmasqFix cache poisoning
    DSA 1624libxsltFix arbitrary code execution
    DSA 1625cupsysFix arbitrary code execution
    DSA 1626httrackFix arbitrary code execution
    DSA 1627openscFix smart card vulnerability
    DSA 1628pdnsFix DNS response spoofing
    DSA 1629postfixFix programming error
    DSA 1630linux-2.6Fix several vulnerabilities
    DSA 1630fai-kernelsFix several vulnerabilities
    DSA 1630user-mode-linuxFix several vulnerabilities
    DSA 1631libxml2Fix denial of service
    DSA 1632tiffFix arbitrary code execution
    DSA 1633slashFix multiple vulnerabilities
    DSA 1634wordnetFix arbitrary code execution
    DSA 1636linux-2.6.24Fix denial of service / information leak
    DSA 1638opensshFix denial of service
    DSA 1639twikiFix arbitrary code execution
    DSA 1640python-djangoFix several vulnerabilities
    DSA 1641phpmyadminFix several vulnerabilities
    DSA 1642horde3Fix cross site scripting
    DSA 1643fetaFix insecure temp file usage
    DSA 1644mplayerFix integer overflows
    DSA 1645lighttpdFix various problems
    DSA 1646squidFix array bounds check
    DSA 1647php5Fix several vulnerabilities
    DSA 1648monFix insecure temporary files
    DSA 1649iceweaselFix several vulnerabilities
    DSA 1650openldap2.3Fix denial of service
    DSA 1651ruby1.8Fix several vulnerabilities
    DSA 1652ruby1.9Fix several vulnerabilities
    DSA 1653linux-2.6Fix several vulnerabilities
    DSA 1653fai-kernelsFix several vulnerabilities
    DSA 1653user-mode-linuxFix several vulnerabilities
    DSA 1654libxml2Fix execution of arbitrary code
    DSA 1655linux-2.6.24Fix several vulnerabilities

How do I upgrade my Debian system?

Login as root and type the following command:
# apt-get update
# apt-get upgrade

Sample output:

Get:1 http://http.us.debian.org stable Release.gpg [386B]
Get:2 http://security.debian.org stable/updates Release.gpg [189B]
Hit http://http.us.debian.org stable Release           
Hit http://security.debian.org stable/updates Release
Ign http://http.us.debian.org stable/main Packages/DiffIndex
Ign http://security.debian.org stable/updates/main Packages/DiffIndex
Ign http://http.us.debian.org stable/non-free Packages/DiffIndex
Ign http://http.us.debian.org stable/contrib Packages/DiffIndex
Ign http://security.debian.org stable/updates/contrib Packages/DiffIndex
Ign http://security.debian.org stable/updates/non-free Packages/DiffI

Setting up apache2-mpm-worker (2.2.3-4+etch6) ...
Starting web server (apache2)....

Setting up apache2 (2.2.3-4+etch6) ...

Reboot the system:
# uname -mrs
# reboot

Make sure everything is working fine:
# uname -a
# netstat -tulpn
# tail -f /var/log/messages
# dmesg | less
# tail -f /var/log/path/to/app.file
# iptables -L -n

Further readings:

Critical Red Hat Enterprise Linux Kernel Update

Red Hat issued an update version of Linux operating system core called kernel that plugs various security holes for RHEL 5.x. This update has been rated as having important security impact. All users are advised to upgrade kernel package.

Security fixes:

a) A missing capability check was found in the Linux kernel do_change_type routine. This could allow a local unprivileged user to gain privileged access or cause a denial of service. (CVE-2008-2931, Important)

b) A flaw was found in the Linux kernel Direct-IO implementation. This could allow a local unprivileged user to cause a denial of service. (CVE-2007-6716, Important)

c) Tobias Klein reported a missing check in the Linux kernel Open Sound System (OSS) implementation. This deficiency could lead to a possible information leak. (CVE-2008-3272, Moderate)

d) a deficiency was found in the Linux kernel virtual filesystem (VFS) implementation. This could allow a local unprivileged user to attempt file creation within deleted directories, possibly causing a denial of service. (CVE-2008-3275, Moderate)

e) A flaw was found in the Linux kernel tmpfs implementation. This could allow a local unprivileged user to read sensitive information from the kernel. (CVE-2007-6417, Moderate)

Bug fix

a) A kernel crash may have occurred on heavily-used Samba servers after 24 to 48 hours of use.

b) On certain systems, if multiple InfiniBand queue pairs simultaneously fell into an error state, an overrun may have occurred, stopping traffic.

c) With bridging, when forward delay was set to zero, setting an interface to the forwarding state was delayed by one or possibly two timers, depending on whether STP was enabled. This may have caused long delays in moving an interface to the forwarding state. This issue caused packet loss when migrating virtual machines, preventing them from being migrated without interrupting applications.

How do I update my kernel?

Login as root and type:
# uname -mrs
# yum update
# reboot
# uname -mrs

Security Alert: How To Stop Firefox Clickjacking Exploit Attack

Really scary exploit attack in wild, which affects all browsers under any desktop operating systems including MS IE, Linux, Apple safari, Opera, Firefox and Adobe flash. Any website that uses CSS, flash and IFRAME (used to serve ads) can be used to attack on end users. Attacker is able to take control of the links that your browser visits. From the article:

In a nutshell, it’s when you visit a malicious website and the attacker is able to take control of the links that your browser visits. The problem affects all of the different browsers except something like lynx. The issue has nothing to do with JavaScript so turning JavaScript off in your browser will not help you. It’s a fundamental flaw with the way your browser works and cannot be fixed with a simple patch. With this exploit, once you’re on the malicious web page, the bad guy can make you click on any link, any button, or anything on the page without you even seeing it happening.

According to victims on several Web forums, the attack is coming from Adobe Flash-based advertising on legitimate sites — including Newsweek, Digg and MSNBC.com.

How do I stop Clickjacking under Firefox?

There are two solutions.

Option #1: Disable everything

Disable scripting and plugins such as flash and others for the time being under Firefox (except adblock plus or no-script plugin). I’ve no idea how to do this under IE or other browsers. Under Firefox clock on Tools > Add-ons > Select each plugin and disable it.

Fig.01: Disable scripting and plugins

Fig.01: Disable scripting and plugins

Shutdown browser. Next, remove Adobe flash from system using apt-get or from your directory. If firefox 3 installed at /opt/firefox/, change directory to /opt/firefox/plugins:
# cd /opt/firefox/plugins
Delete flash and other plugins files:
# rm *
This should work for other browsers too.

Option #2: Use Noscript To Stop Attack

Download latest version of NoScript firefox plugin. NoScript for Firefox pre-emptively blocks malicious scripts and allows JavaScript, Java and other potentially dangerous content only from sites you trust. Once installed restar firefox. Click on NoScript icon located on bottom right status bar > Select options > Click on Forbid [IFRAME] > Ok

Fig.01: Mitigation for Clickjacking under Firefox with NoScript Plugin

Fig.02: Mitigation for Clickjacking under Firefox with NoScript Plugin

Bonus option # 3: Use lynx

Lynx and other text based browsers are not affected by this exploit. Lynx is a free open-source, text-only Web browser. Recent version works under Mac OS X, All versions of Windows and UNIX like operating systems. You install lynx using apt-get or yum command:
# apt-get install lynx
# yum install lynx

Further readings:

  1. More info about clickjacking
  2. NoScript plugins
  3. Clickjacking demo / proof of concept demo (warning it will hijack your clipboard, to stop just close browser.)
  4. Clickjacking: Researchers raise alert for scary new cross-browser exploit

Security Alert: Debian OpenSSH packages Fix Denial of Service

Debian Linux project released the OpenSSH security updates for computers powered by its Debian Linux operating systems. The Openssh package has remote unsafe signal handler DoS Vulnerability. It has been discovered that the signal handler implementing the login timeout in Debian’s version of the OpenSSH server uses functions which are not async-signal-safe, leading to a denial of service vulnerability.

Systems affected by this issue suffer from lots of zombie sshd processes. Processes stuck with a “[net]” process title have also been observed. Over time, a sufficient number of processes may accumulate such that further login attempts are impossible. Presence of these processes does not indicate active exploitation of this vulnerability.

Package        : openssh
Vulnerability  : remote
Problem type   : unsafe signal handler
Debian-specific: no
CVE Id(s)      : CVE-2008-4109
Debian Bug     : 498678

How do I fix this problem?

Login as root and type the following commands to update the internal database, followed by corrected packages installation:
# apt-get update
# apt-get upgrade

Critical Red hat / Fedora Linux Openssh Security Update

Last week one or more of Red Hat’s servers got cracked. Now, it has been revealed that both Fedora and Red Hat servers have been compromised. As a result Fedora is changing their package signing key. The intruder was able to sign a small number of OpenSSH packages relating only to Red Hat Enterprise Linux 4 (i386 and x86_64 architectures only) and Red Hat Enterprise Linux 5 (x86_64
architecture only).

This update has been rated as having critical security impact. If your Red hat based server directly connected to the Internet, immediately patch up the system.

From the RHN announcement:

Last week Red Hat detected an intrusion on certain of its computer systems and took immediate action. While the investigation into the intrusion is on-going, our initial focus was to review and test
the distribution channel we use with our customers, Red Hat Network (RHN) and its associated security measures. Based on these efforts, we remain highly confident that our systems and processes prevented the intrusion from compromising RHN or the content distributed via RHN and accordingly believe that customers who keep their systems updated using Red Hat Network are not at risk. We are issuing this alert primarily for those who may obtain Red Hat binary packages via channels other than
those of official Red Hat subscribers.

Following products are affected:
=> Red Hat Desktop (v. 4)
=> Red Hat Enterprise Linux (v. 5 server)
=> Red Hat Enterprise Linux AS (v. 4)
=> Red Hat Enterprise Linux AS (v. 4.5.z)
=> Red Hat Enterprise Linux Desktop (v. 5 client)
=> Red Hat Enterprise Linux ES (v. 4)
=> Red Hat Enterprise Linux ES (v. 4.5.z)
=> Red Hat Enterprise Linux WS (v. 4)

How do I patch up my system?

Login as the root and type the following command:
# yum update

This is the main reason I don’t use Fedora in a production.

More information:

Now, Red hat did not disclosed how the hell attacker got in to the server. I’d like to know more about that – was it 0 day bug or plain old good social engineering hack?

Updated for accuracy – CentOS is not affected by this bug, see the comments below.