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The Symlink Protection patchset is available for free for CentOS 6 & 7, even if you are not running KernelCare

The Symlink Protection patchset is available for free for CentOS 6 & 7, even if you are not running KernelCare

A few weeks ago we released the KernelCare "Extra" Patchset with the security fixes and the symlink protection available to all KernelCare customers running CentOS kernels. Today we are pleased to share that you can get the Symlink Protection Patchset for CentOS 6 and 7 at no cost, even if you don’t have licenses of KernelCare.

We’ve been discussing with the cPanel team on how to help with hardening of their customers' system kernels. This Symlink Protection Patchset will protect CentOS 6 and 7 systems and will help defend shared hosting servers, including the cPanel servers, against symlink attacks.

A symlink race attack is frequently used against shared hosting servers. It allows a malicious user to serve files that belong to other users by creating a symbolic link to those files. It is often used to access config.php files that belong to others. This patchset helps protect against such attacks.

Note that this patchset includes only the symlink protection, and does not include the security fixes (those are available to KernelCare customers) - you will still need to update kernel and REBOOT each time new CentOS kernel is released to keep your kernel secure.

We recommend the installation of this patchset on CentOS 6 and CentOS 7 to make your servers more secure.

How to install the free symlink protection patchset:

Below we provide instructions on how to install KernelCare and run this patchset for free. Though this symlink protection patchset is part of KernelCare, it does not require you to purchase a license or even register for the KernelCare free trial (if you choose to purchase a license at a later date, information on how to upgrade will be published in the documentation soon).

To enable the symlink protection, perform the following steps:

First, install KernelCare client:

curl -s https://repo.cloudlinux.com/kernelcare/kernelcare_install.sh | bash

Enable free patch type, this patch type doesn't require a license

kcarectl --set-patch-type free --update

The ‘free’ patch will be applied on the next update.

. . .

During the installation, you should see something similar to:


OS: CentOS6
kernel: kernel-2.6.32-696.el6
time: 2017-06-22 16:13:40
uname: 2.6.32-642.15.1.el6

kpatch-name: 2.6.32/symlink-protection.patch
kpatch-description: symlink protection // If you see this patch, it mean that you can enable symlink protection.
kpatch-kernel: kernel-2.6.32-279.2.1.el6
kpatch-cve: N/A
kpatch-cvss: N/A
kpatch-cve-url: N/A
kpatch-patch-url: https://gerrit.cloudlinux.com/#/c/16508/

kpatch-name: 2.6.32/symlink-protection.kpatch-1.patch
kpatch-description: symlink protection (kpatch adaptation)
kpatch-kernel: kernel-2.6.32-279.2.1.el6
kpatch-cve: N/A
kpatch-cvss: N/A
kpatch-cve-url: N/A
kpatch-patch-url: https://gerrit.cloudlinux.com/#/c/16508/


Edit the file /etc/sysconfig/kcare/sysctl.conf (or create it if it doesn't exist) - add the lines:

fs.enforce_symlinksifowner = 1
fs.symlinkown_gid = 48


Execute:

sysctl -w fs.enforce_symlinksifowner=1
sysctl -w fs.symlinkown_gid=48

Note: On standard RPM Apache installation, Apache is usually running under GID 48. On cPanel servers, Apache is running under user nobody, GID 99.

Click here to learn more about KernelCare.
 

Beta: EasyApache 4 updated
Beta: LVE Manager updated
 

Comments 95

Guest - mustafa on Friday, 13 October 2017 00:35

Hello

First kernel update and later Cpanel install

Or

First Cpanel install and later kernel update required?

Thanks

Hello First kernel update and later Cpanel install Or First Cpanel install and later kernel update required? Thanks
Guest - mustafa on Saturday, 14 October 2017 22:38

Hello

I installed fresh centos 6.9 and try,

[[email protected]]# kcarectl --set-patch-type free --update
'free' patch type selected
Downloading updates
Patch Level 208 applied, effective kernel version 2.6.32-696.13.2.el6
Updates already downloaded
Kernel is safe


[[email protected]]# nano /etc/sysconfig/kcare/sysctl.conf
NOT FOUND

Any problem?

Hello I installed fresh centos 6.9 and try, [[email protected]]# kcarectl --set-patch-type free --update 'free' patch type selected Downloading updates Patch Level 208 applied, effective kernel version 2.6.32-696.13.2.el6 [b]Updates already downloaded Kernel is safe[/b] [[email protected]]# nano /etc/sysconfig/kcare/sysctl.conf NOT FOUND Any problem?
Guest - sg on Wednesday, 18 October 2017 22:23

same issue here

same issue here
Guest - Kailash on Tuesday, 17 October 2017 12:31

If I am using cPanel with Apache, do I need to use following line:

fs.symlinkown_gid=99

"99" instead of "48"?

Thanks,
Kailash

If I am using cPanel with Apache, do I need to use following line: fs.symlinkown_gid=99 "99" instead of "48"? Thanks, Kailash
Guest - Rodrigo on Thursday, 19 October 2017 19:01

Same issue here²

I created the file manually, is this a problem?

Same issue here² I created the file manually, is this a problem?
Guest - sg on Wednesday, 18 October 2017 22:21

/etc/sysconfig/kcare/sysctl.conf file does not exist

/etc/sysconfig/kcare/sysctl.conf file does not exist
Guest - Esteban on Friday, 20 October 2017 02:39

HI!

1) Thanks.
2) Is this going to be available on further cpanel/whm centos kernel updates?

HI! 1) Thanks. 2) Is this going to be available on further cpanel/whm centos kernel updates?
Guest - mustafa on Friday, 20 October 2017 23:42

Hello

/etc/sysconfig/kcare/sysctl.conf file does not exist

--

I try
sysctl -w fs.enforce_symlinksifowner=1
sysctl -w fs.symlinkown_gid=48

I checked /etc/sysctl.conf

But not added
fs.enforce_symlinksifowner = 1
fs.symlinkown_gid = 48

Hello /etc/sysconfig/kcare/sysctl.conf [b]file does not exist[/b] -- I try sysctl -w fs.enforce_symlinksifowner=1 sysctl -w fs.symlinkown_gid=48 I checked [b]/etc/sysctl.conf[/b] [b]But not added[/b] fs.enforce_symlinksifowner = 1 fs.symlinkown_gid = 48
Guest - Anderson on Wednesday, 25 October 2017 03:48

You can help?

[[email protected]]# kcarectl --set-patch-type free --update
Unknown Kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64)

[[email protected]]# /usr/bin/kcarectl --update
Unknown Kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64)

[[email protected]]# kcarectl --info
Unknown kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64), no patches available

You can help? [[email protected]]# kcarectl --set-patch-type free --update Unknown Kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64) [[email protected]]# /usr/bin/kcarectl --update Unknown Kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64) [[email protected]]# kcarectl --info Unknown kernel (CentOS Linux 3.10.0-693.5.2.el7.x86_64), no patches available
Guest - s on Wednesday, 25 October 2017 17:17

Hi I did this and manually created sysctl.conf then ran
fs.enforce_symlinksifowner = 1
fs.symlinkown_gid = 99 (for cpanel servers)

It still says "No symlink protection detected" in WHM security advisor.

Hi I did this and manually created sysctl.conf then ran fs.enforce_symlinksifowner = 1 fs.symlinkown_gid = 99 (for cpanel servers) It still says "No symlink protection detected" in WHM security advisor.
Guest - Alex on Monday, 30 October 2017 19:55

Hello,

I just installed the patch on cloud sever running "CENTOS 7.4 kvm" " WHM: v66.0.29".
I rebooted the server multiple times and i still see the message "You must reboot the server to apply kernel updates." on WHM.

Hello, I just installed the patch on cloud sever running "CENTOS 7.4 kvm" " WHM: v66.0.29". I rebooted the server multiple times and i still see the message "You must reboot the server to apply kernel updates." on WHM.
Guest - Mehmood Ahmed on Sunday, 12 November 2017 08:41

In CENTOS 7.4 kvm v68.0.12

uname -r
3.10.0-693.5.2.el7.x86_64

kcarectl --info

kpatch-state: patch is applied
kpatch-for: Linux version 3.10.0-693.5.2.el7.x86_64 ([email protected]) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) ) #1 SMP Fri Oct 20 20:32:50 UTC 2017
kpatch-build-time: Tue Oct 24 22:49:09 2017
kpatch-description: 2-free;3.10.0-693.5.2.el7

But in security advisor its showing

No symlink protection detected

You do not appear to have any symlink protection enabled on this server. You can protect against this in multiple ways. Please review the following documentation to find a solution that is suited to your needs.

may i ignore that warning, pls help

In CENTOS 7.4 kvm v68.0.12 uname -r 3.10.0-693.5.2.el7.x86_64 kcarectl --info kpatch-state: patch is applied kpatch-for: Linux version 3.10.0-693.5.2.el7.x86_64 ([email protected]) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) ) #1 SMP Fri Oct 20 20:32:50 UTC 2017 kpatch-build-time: Tue Oct 24 22:49:09 2017 kpatch-description: 2-free;3.10.0-693.5.2.el7 But in security advisor its showing No symlink protection detected You do not appear to have any symlink protection enabled on this server. You can protect against this in multiple ways. Please review the following documentation to find a solution that is suited to your needs. may i ignore that warning, pls help
Igor Seletskiy on Wednesday, 15 November 2017 15:27

Security advisor doesn't know yet how to detect it. cPanel is working on it. You can ignore the warning.

Security advisor doesn't know yet how to detect it. cPanel is working on it. You can ignore the warning.
Guest - Damjan on Monday, 13 November 2017 15:16

Will this work for OpenVZ containers if installed on host node?

Will this work for OpenVZ containers if installed on host node?
Igor Seletskiy on Wednesday, 15 November 2017 15:26
Guest - Faheem on Wednesday, 15 November 2017 14:06

There is no sysctl.conf file in /etc/sysconfig/kcare/
I'm using KernelCare with license

There is no sysctl.conf file in /etc/sysconfig/kcare/ I'm using KernelCare with license
Guest - s on Wednesday, 15 November 2017 15:03

just create manually and add required text

we've done this on one server but didn't do the others as there's nothing to say it's actually working until cpanel stop saying in security advisor that there is no symlink protection, I know cloudlinux are in discussions with them about this.

just create manually and add required text we've done this on one server but didn't do the others as there's nothing to say it's actually working until cpanel stop saying in security advisor that there is no symlink protection, I know cloudlinux are in discussions with them about this.
Guest - Fabian Marsiglione on Wednesday, 15 November 2017 15:13

Hello IGor,

This is necessary for all CL installations?
In my servers, without do this i get this in the security advisor from WHM :

"Apache Symlink Protection: CloudLinux protections are in effect.
You appear to have sufficient protections from Apache Symlink Attacks. If you have not already, consider increasing protection with CageFS. For further information on symlink attack protection see our suggestions on it."

AND THIS :

"Apache Symlink Protection: Cloudlinux CageFS protections are in effect
You are running CageFS. This provides filesystem level protections for your users and server."

AND FINALLY THIS : (ALL IN GREEN)

"The system kernel is up-to-date at version “2.6.32-673.26.1.lve1.4.30.el6.x86_64”."

It´s ok or is better to apply this patch too?
Regards
Fabian

Hello IGor, This is necessary for all CL installations? In my servers, without do this i get this in the security advisor from WHM : "Apache Symlink Protection: CloudLinux protections are in effect. You appear to have sufficient protections from Apache Symlink Attacks. If you have not already, consider increasing protection with CageFS. For further information on symlink attack protection see our suggestions on it." AND THIS : "Apache Symlink Protection: Cloudlinux CageFS protections are in effect You are running CageFS. This provides filesystem level protections for your users and server." AND FINALLY THIS : (ALL IN GREEN) "The system kernel is up-to-date at version “2.6.32-673.26.1.lve1.4.30.el6.x86_64”." It´s ok or is better to apply this patch too? Regards Fabian
Igor Seletskiy on Wednesday, 15 November 2017 15:25

You don't need it on CloudLinux servers (CloudLinux has it built in). It is for CentOS servers only.

You don't need it on CloudLinux servers (CloudLinux has it built in). It is for CentOS servers only.
Guest - has on Wednesday, 15 November 2017 15:23

Hi
Can install and use with DirectAdmin on CentOS 7 ?
How to uninstall if needed ?
Thanks

Hi Can install and use with DirectAdmin on CentOS 7 ? How to uninstall if needed ? Thanks
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