A continuation of the previous exploits. http://isec.pl/vulnerabilities/isec-0025-syscall-emulation.txt
Details about the 0 day exploit and how to test whether your system is exploitable or not. However no need to get panicked as this particular exploit was with l33t hackers for last 2 years as you can see at the above link. Now since it is public now, take an extra care if uname -m gives you a x86_64.
Two CVE candidates are there – CVE-2010-3081 and CVE-2010-3301. One will affect the server and other don’t.
Temporary solution would be to follow https://access.redhat.com/kb/docs/DOC-40265Continue Reading
Compiling custom kernel has its own advantages and disadvantages. It helps to optimize the kernel to your environment (hardware and usage patterns). I shall try to guide you through Kernel recompilation process.
Download the kernel source
Note: Replace x.y.z with actual version number.
Extract the source file
Patching the Kernel
If you are requested to apply any patches , follow these steps
a) Move the downloaded kernel patch to the
b) Extract the patch file
c) Patch the kernel source using the extracted patch file
patch -p1 < patchfile-2.2.x
Now the Kernel Source is patched against known vulnerabilities.
If you are trying to upgrade the Kernel of already running server , it is always better use the existing configuration. To do this follow these steps
Linux Server1 2.6.18-164.el5 #1 SMP Thu Sep 3 03:28:30 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux
# cd /boot
There you can see different configuration files as given below
config-2.6.18-128.el5 initrd-2.6.18-128.el5.img message
config-2.6.18-164.el5 initrd-2.6.18-164.el5.img quota.user*
identify the configuration file corresponding to the version of OS installed , In our case it is config-2.6.18-164.el5 . We are copying this file to the downloaded kernel source to use it during configuration.
#cp -p config-2.6.18-164.el5 /usr/local/src/linux-x.y.z/.config
# make clean
# make mrproper
# make menuconfig
You have to select different options as per your need. If you intended to use the existing configuration ,specify the path to the file ( .config in this case) by selecting the option
“Load an Alternative configuration file”
Step 5: Compilation
Compile the Kernel using the following commands
Compile to create a compressed kernel image
Compile kernel modules:
Install kernel modules
# make modules_install
Step 6: Install Kernel
If the above steps completed without any errors , now its the time to Install the new Kernel
# make install
It will install three files into /boot directory as well as modification to your kernel grub configuration file:
Step 7: Create the Initrd image
Type the following command :
# cd /boot
mkinitrd -o initrd.img-x.y.x x.y.z
initrd images contains device driver which needed to load rest of the operating system later on. Not all computer requires it, but it is better to create one
Step 8: Boot Loader Modification
Mofdify the boot loader to boot the new OS as default . Check the documentaions corresponding to your boot loader
Step 9: The last step
execute the following command
Wait a few minutes and once it is up , you can see that the new Kernel is loadedContinue Reading