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Posts Tagged ‘centos’

CVE-2010-3081: 64bit Linux Kernel Root Exploit

September 20th, 2010 1 comment

Well its been a heavy week on the security front, first up is a Linux root exploit for 64bit Machines.

A vulnerability in the 32-bit compatibility layer for 64-bit systems was reported. It is caused by insecure allocation of user space memory when translating system call inputs to 64-bit. A stack pointer underflow can occur when using the “compat_alloc_user_space” method with an arbitrary length input.

What does that mean? Essentially, some sanity checks in the compat_alloc_user_space function to check the length and ensure that the pointer to the block of memory is within the user-space of the process is valid was missing. The fix has already been committed but if you are running any x64 versions of Linux, make sure you update your Kernel – especially now that the exploit code is publicly available!

Read up on the exploit by Jeff Arnold from Ksplice and use this very useful CVE-2010-3081 high-profile exploit detection tool to determine if you’re boxens are already compromised.

Of particular note from his article is the breadth of exploitable distributions – see the references below for vendor specific information:

This vulnerability was introduced into the Linux kernel in April 2008, and so essentially every distribution is affected, including RHEL, CentOS, Debian, Ubuntu, Parallels Virtuozzo Containers, OpenVZ, CloudLinux, and SuSE, among others. A few vendors have released kernels that fix the vulnerability if you reboot, but other vendors, including Red Hat, are still working on releasing an updated kernel.

After downloading and running the tool under a non-sudo account, you should cheerfully get the following output.

thushan@dingo:~/tmp$ ./diagnose-2010-3081
Diagnostic tool for public CVE-2010-3081 exploit -- Ksplice, Inc.
(see http://www.ksplice.com/uptrack/cve-2010-3081)

$$$ Kernel release: 2.6.32-23-server
!!! Not a RHEL kernel, will skip LSM method
$$$ Backdoor in LSM (1/3): not available.
$$$ Backdoor in timer_list_fops (2/3): checking...not present.
$$$ Backdoor in IDT (3/3): checking...not present.

Your system is free from the backdoors that would be left in memory by the published exploit for CVE-2010-3081.
thushan@dingo:~/tmp$

If not, its time to put those security drills into action!

References

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CentOS 5.4 Released!

October 23rd, 2009 No comments

CentOS 5.4 has been released! Woo yeah, its been a while since RHEL 5.4 has been out but checkout the release notes for a list of changes.

Download mirrors are being updated but if your local, here are a couple of Australian Mirrors.

CentOS 5.4 x86

CentOS 5.4 x64

I just did a inplace 5.3->5.4 upgrade with a yum update. With a localised mirror, blindingly fast too!

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Redhat 5.4 released, CentOS 5.4 is coming soon!

September 3rd, 2009 No comments

If you haven’t heard already, Redhat has released the eagerly anticipated 5.4 release of Redhat Enterprise Linux at their Redhat Summit in Chicago. As expected, Redhat looks to have moved from using Xen as their favoured virtualisation hypervisor to using KVM (which is an integral part of the Linux Kernel). All this will eventually go into RHEV.

All the changes in this release are documented in the  Release Notes, unfortunately Ext4 is still not considered usable in this release (they’re targetting for RHEL6 possibly).

So what of the RHEL clone CentOS? Possibly a 2-4 week delay it seems. WOO! In the meantime, upgrading from 5.3 is easy peasy.

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Mounting and activating LVM Volumes from BootCD to recover data in linux

September 2nd, 2009 3 comments

I’ve been working heavily with Red Hat Enterprise Linux (and subsequently CentOS) the past few months (shh! dont tell my MSFT homey!) and one of the great things about CentOS and RHEL is that they both install using LVM – which is a helluvah lot easier when time passes and you realise your running out of space on a drive.

But today I had to recover some data from an LVM partition and copy over some bits to another partition without actually booting the CentOS install (it was bj0rked by yours truely!). What to do? Throw in a Ubuntu LiveCD (or another) and just mount the partitions :-)

First thing we need to do is install LVM – remember we need to be sudo for these to work.

$ aptitude install lvm2

Then scan for any available physical volumes on any of the drives.

$ pvscan

Scan for any Volume Groups that may be present.

$ vgscan

Now activate any of the Volume Groups that it finds, running this makes the logical volumes known to the kernel.

$ vgchange –available y

Then let it scan for any Logical Volumes on any drives

$ lvscan

After running the logical volume scan it will show the path to the LVM mount path, for my boxen it gives something like this

ACTIVE            ‘/dev/LVM/Data‘ [5.26 TB] inherit

You simply mount the path specified and browse like normally :-)

$ mount /dev/LVM/Data /mnt

Enjoy.

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UPDATE: Installing CentOS 5.x on ASUS P5WDH-Deluxe

May 15th, 2009 No comments

Earlier I mentioned that getting CentOS 5.x to install on the ASUS P5WDH-Deluxe motherboard wasn’t as easy as I first thought and suggested you disable a few things (mentioned in the previous post). However today I’ve got another solution thats less headachey.

Forget disabling ACPI and booting with irqpoll, instead you will need to disable the onboard JMicron controller (mine was always disabled!) and make sure if your using a PATA optical drive you use the ICHR7 port – thats the blue IDE port in the middle of the board at the bottom at the picture.

ASUS P5W DH Deluxe

Next in the Main tab

[IDE Configuration]

  • Configure SATA As [AHCI]
  • ALPE and ASP [Enabled]
  • IDE Detect Time Out (Sec) [0]

Then make sure that JMicron SATA/PATA Controller is disabled (in the Advanced -> Onboard Devices Configuration) and re-enable the   ACPI 2.0 Support and ACPI APIC support (in the Power tab).

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Booting CentOS 5.3 on ASUS P5WDH Deluxe

May 12th, 2009 No comments

As my journey to find the perfect setup for the new Zeus continues, I thought I’d try out CentOS 5.3. One of the many benefits of running on an open-setup, lots of HDDs, lots of room to move around, not much time though :(

If you find you get stuck during the installation for CentOS (and subsequently RHEL & Fedora) heres how to get things to boot.

In the BIOS:

Power

  • Suspend Mode [Auto]
  • ACPI 2.0 Support [No]
  • ACPI APIC Support [Disabled] *uhoh*

Then when you boot, press {F4} to get the kernel options, and at the end append:

$ boot: linux irqpoll

This will hopefully boot the installer for you.

No need to do all that, see the updated post which is simpler and less hassles.

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