Auditing USB Question

Josh jokajak at gmail.com
Fri Aug 2 14:30:54 UTC 2013


On 08/01/2013 02:04 PM, Trevor Vaughan wrote:
> You don't have to mount media to pull off the data.
>
> dd + one of any number of user space utils can extract data.
>
> But, UDEV is probably the correct subsystem for this.
>
> Trevor
>
>
> On Thu, Aug 1, 2013 at 12:35 PM, Steve Grubb <sgrubb at redhat.com 
> <mailto:sgrubb at redhat.com>> wrote:
>
>     On Wednesday, July 31, 2013 08:15:21 PM Josh wrote:
>     > That appears to only cover the mounting of filesystems, not any
>     usb device
>     > insertion.  Specifically I'd like to capture the insertion of a USB
>     > keyboard, USB mouse, or USB thumb-drive.
>
>     There is no support for that. Auditing is mostly shaped by common
>     criteria
>     requirements. CC takes the point of view that data import and
>     export is of
>     interest. In order to do that, you have to mount a file system.
>     So, the
>     solution is to watch for mounts. The act of inserting a device has
>     not been
>     considered security relevant because it also says that there is
>     physical
>     security of the data center and random people can't stick random
>     devices into
>     the computer
>
>     That said...there is the real world. I could see this being
>     interesting for
>     very paranoid setups where a random device could be inserted and
>     start fuzzing
>     the kernel to inject code. But if we consider this, there is also
>     bluetooth
>     and firewire and who knows what other interface to worry about.
>
>     It might be possible to find the udev code that gets executed and
>     place a watch
>     on that. Or perhaps modify udev code to send a AUDIT_TRUSTED_APP
>     event which
>     ausearch/report will not impose and control over.
>
>     -Steve
>
>     --
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>
>
>
>
> -- 
> Trevor Vaughan
> Vice President, Onyx Point, Inc
> (410) 541-6699
> tvaughan at onyxpoint.com <mailto:tvaughan at onyxpoint.com>
>
> -- This account not approved for unencrypted proprietary information --
>
>
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I decided to write a simple udev rule that is triggered when a USB 
device is added.  From here I can use environment variables to choose 
which data gets sent to the audit system as a USER message. This will be 
enough for our purposes.

For reverence, here is the udev rule:

ACTION=="add", SUBSYSTEM=="usb", RUN+="/usr/local/sbin/usb_device_add.sh"

Thanks!
-josh
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