Implementing a more generic approach allows flexibility for other systems and
environments. Since the SSG is aimed to support a large variety of environments, it seems
more appropriate to take the generic approach as opposed to a UDEV approach for a specific
device. Just my 2 cents.
I have shared plenty of grief in applying this requirement in different environments. This
is my lessons learned.
Best regards,
Trey Henefield, CISSP
Senior IAVA Engineer
Ultra Electronics
Advanced Tactical Systems, Inc.
4101 Smith School Road
Building IV, Suite 100
Austin, TX 78744 USA
Trey.Henefield(a)ultra-ats.com
Tel: +1 512 327 6795 ext. 647
Fax: +1 512 327 8043
Mobile: +1 512 541 6450
www.ultra-ats.com
From: scap-security-guide-bounces(a)lists.fedorahosted.org
[mailto:scap-security-guide-bounces@lists.fedorahosted.org] On Behalf Of Trevor Vaughan
Sent: Thursday, April 17, 2014 2:38 PM
To: SCAP Security Guide
Subject: Re: [PATCH] [RHEL/6] Search for nousb kernel command line argument in
/etc/grub.conf within bootloader_nousb_argument check case-insensitively
So, wouldn't this be better approached as a udev requirement?
I've been avoiding udev for ages just because I don't want to get pummelled over
the complexity but this is exactly what it can do, isn't it?
Instead of saying that all USB keyboards are allowed, if you know your vendor, then you
say that exactly the keyboards you expect to be on your systems are allowed, etc...
I understand that no USB at the kernel level is safer but this is pushing my
'usability vs security' balance warnings.
I.e. if, for whatever reason, I HAVE to use something USB on a system that can't have
any downtime, you'd better believe that I'm going to leave usb on in the kernel.
And, realistically, isn't that most of the systems you're trying to protect the
most?
http://www.irongeek.com/i.php?page=security/plug-and-prey-malicious-usb-d...
As for VMs, if I wanted to plug a USB device into a VM, I would need administrative access
to the physical host to be able to attach the virtual device. If that's the case it
doesn't really matter since I can pretty much do whatever I like to the VM (including
copying its memory and disk) and not worry about it.
Yes, I know, whining and no patches....but I'm trying to have constructive whining
;-).
Thanks,
Trevor
On Thu, Apr 17, 2014 at 3:20 PM, Trey Henefield
<trey.henefield@ultra-ats.com<mailto:trey.henefield@ultra-ats.com>> wrote:
We have a mix a systems to which some require USB and some do not. While it’s not feasible
to know the need of every system when applying this requirement, I have found some logic
that seems to work:
USB_DEVICE=$(grep 'Product=' /proc/bus/usb/devices | egrep -ic '(ps2 to usb
adapter|keyboard|kvm|sc reader)')
If [ $USB_DEVICE = 0 ]; then
DO SOME ACTION
fi
The above will check for a USB keyboard, a PS2 to USB adapter (needed for a USB keyboard
in some cases), a USB KVM, and a CAC reader (only approved versions are USB).
It may be useful to add that logic to your fix.
Best regards,
Trey Henefield, CISSP
Senior IAVA Engineer
Ultra Electronics
Advanced Tactical Systems, Inc.
4101 Smith School Road
Building IV, Suite 100
Austin, TX 78744 USA
Trey.Henefield@ultra-ats.com<mailto:Trey.Henefield@ultra-ats.com>
Tel: +1 512 327 6795 ext. 647<tel:%2B1%20512%20327%206795%20ext.%20647>
Fax: +1 512 327 8043<tel:%2B1%20512%20327%208043>
Mobile: +1 512 541 6450<tel:%2B1%20512%20541%206450>
www.ultra-ats.com<http://www.ultra-ats.com>
From:
scap-security-guide-bounces@lists.fedorahosted.org<mailto:scap-security-guide-bounces@lists.fedorahosted.org>
[mailto:scap-security-guide-bounces@lists.fedorahosted.org<mailto:scap-security-guide-bounces@lists.fedorahosted.org>]
On Behalf Of Trevor Vaughan
Sent: Thursday, April 17, 2014 7:11 AM
To: SCAP Security Guide
Subject: Re: [PATCH] [RHEL/6] Search for nousb kernel command line argument in
/etc/grub.conf within bootloader_nousb_argument check case-insensitively
Just out of curiosity, is adding nousb to the grub command line actually feasible for
enforcement?
I can't remember the last time I used a system where I didn't need a USB keyboard
at some point (can you even buy server class systems with PS/2 support any more?)
Trevor
On Wed, Apr 16, 2014 at 8:23 PM, Shawn Wells
<shawn@redhat.com<mailto:shawn@redhat.com>> wrote:
On 4/16/14, 5:08 PM, Kayse, Josh wrote:
On Apr 16, 2014, at 8:06 PM, Kayse, Josh
<Joshua.Kayse@gtri.gatech.edu<mailto:Joshua.Kayse@gtri.gatech.edu>> wrote:
On Apr 16, 2014, at 7:59 PM, Shawn Wells
<shawn@redhat.com<mailto:shawn@redhat.com>> wrote:
On 4/16/14, 5:44 AM, Jan Lieskovsky wrote:
Patch summary:
* check for 'nousb' argument on kernel command line in /etc/grub.conf
within the bootloader_nousb_argument check in a case-insensitive way
* update comments where appropriate
* add test attestation timestamp
* replace path + filename ind construct with filepath one
Testing report:
* Tested on RHEL-6. Works fine.
I wasn't sure if nousb was case insensitive, so I checked
https://www.kernel.org/doc/Documentation/kernel-parameters.txt
And found this:
Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will
be entered as an environment variable, whereas its absence indicates that
it will appear as a kernel argument readable via /proc/cmdline by programs
running once the system is up.
"nousb" was in the list as case sensitive.
Applied your patch (RHEL 6.5), added "nOuSB," and things seem to check out.
Should we follow the kernel docs (which say case sensitive), or allow insensitivity since
it actually works?
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I’d like to point out that the selinux parameter is also within that list. I vote we
should follow what actually works and assume the kernel docs are out of date.
-josh
Also, according to
https://github.com/torvalds/linux/blame/master/Documentation/kernel-param... that
line was last changed 2005. Perhaps someone should brave lkml and submit a patch.
-josh
Thanks for that link!
Ack to Jan's patch.
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Vice President, Onyx Point, Inc
(410) 541-6699<tel:%28410%29%20541-6699>
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