From: "Trevor Vaughan" <tvaughan(a)onyxpoint.com>
To: "SCAP Security Guide" <scap-security-guide(a)lists.fedorahosted.org>
Sent: Thursday, April 17, 2014 9:37:38 PM
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?
Checking /etc/grub.conf settings instead of udev ones has the advantage,
the system to be scanned doesn't need to run (offline scan of provided VM
image) to be able to decide if the system is configured properly.
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
Thank you && Regards, Jan.
--
Jan iankko Lieskovsky / Red Hat Security Technologies Team
On Thu, Apr 17, 2014 at 3:20 PM, Trey Henefield <
trey.henefield(a)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(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(a)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(a)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(a)gtri.gatech.edu >
wrote:
On Apr 16, 2014, at 7:59 PM, Shawn Wells < shawn(a)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?
_______________________________________________
scap-security-guide mailing list
scap-security-guide(a)lists.fedorahosted.org
https://lists.fedorahosted.org/mailman/listinfo/scap-security-guide
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.
_______________________________________________
scap-security-guide mailing list
scap-security-guide(a)lists.fedorahosted.org
https://lists.fedorahosted.org/mailman/listinfo/scap-security-guide
--
Trevor Vaughan
Vice President, Onyx Point, Inc
(410) 541-6699
tvaughan(a)onyxpoint.com
-- This account not approved for unencrypted proprietary information --
Disclaimer
The information contained in this communication from
trey.henefield(a)ultra-ats.com sent at 2014-04-17 15:20:52 is private and may
be legally privileged or export controlled. It is intended solely for use by
scap-security-guide(a)lists.fedorahosted.org and others authorized to receive
it. If you are not scap-security-guide(a)lists.fedorahosted.org you are hereby
notified that any disclosure, copying, distribution or taking action in
reliance of the contents of this information is strictly prohibited and may
be unlawful.
_______________________________________________
scap-security-guide mailing list
scap-security-guide(a)lists.fedorahosted.org
https://lists.fedorahosted.org/mailman/listinfo/scap-security-guide
--
Trevor Vaughan
Vice President, Onyx Point, Inc
(410) 541-6699
tvaughan(a)onyxpoint.com
-- This account not approved for unencrypted proprietary information --
_______________________________________________
scap-security-guide mailing list
scap-security-guide(a)lists.fedorahosted.org
https://lists.fedorahosted.org/mailman/listinfo/scap-security-guide