Announcing Detroit Dave's Raves

One of my SANS 503 Mentor students has started his own blog. Check it out at:
http://detroitdavesraves.blogspot.com/

How a Single Piece of Paper Can Saturate a WAN Link

At work, one of our remote business units was experiencing slowness in their WAN link. Our Network Architect began looking into the problem and found that one particular device on their network was sending enormous amounts of traffic over the link. Looking into it further, he discovered that the device was one of our security cameras in the business unit's server room. He then came to see us and asked about the camera.

This particular camera is motion-activated and therefore shouldn't have been capturing all the time, but it was. We looked at some of the videos and, at first, didn't see anything out of the ordinary. After racking our brains for a few minutes, we finally noticed that there was a piece of paper taped to the front of one of the server racks. The paper was taped in the middle, allowing the sides to flap in the wind of the air conditioner. This created just enough motion to trigger the camera to record and transmit its video.

All of this resulted in a call to the technician at the business unit that went something like this:

"We've discovered the problem with your WAN link. Please go to your server room and remove the piece of paper taped to the front of the server rack. Your WAN link should then magically speed up. Thank you."

My modest proposal is that paper is obviously increasing our bandwidth costs and we should therefore go completely paperless.

SANS GCIA Gold Paper on Snort 3.0 Beta 3

My SANS GCIA Gold Paper on Snort 3.0 Beta 3 has been posted to the SANS Reading Room!

Wireshark 1.0.7 is out!

Wireshark 1.0.7 has been released. Please upgrade ASAP! For more information about the release, please see:
http://www.wireshark.org/docs/relnotes/wireshark-1.0.7.html

Snort 2.8.4 is out!

Snort 2.8.4 has been released. From http://www.snort.org/pub-bin/snortnews.cgi#864:

Snort 2.8.4 is now available on snort.org, at http://www.snort.org/dl/

Snort 2.8.4 introduces:

- A revised DCE/RPC preprocessor with more rule options

With the new DCE/RPC preprocessor, there will be a number of updates to the rules. Please be sure to update your rules to the latest when that package is available (next few days).

- Support for IPv6 in Frag3 and all application preprocessors

- Improved target-based support in preprocessors

- Option to automatically pre-filter traffic that is not inspected in order to improve performance

- Several other improvements and fixes

Please see the release notes and changelog for more details.

Please submit bugs, questions, and feedback to bugs@snort.org.

Happy Snorting!
The Snort Release Team

For more information about the new DCERPC rules, please see:
http://www.snort.org/vrt/advisories/vrt-rules-2009-04-08.html

Snort 3.0 (SnortSP) Beta 3 -- Inline Bridging Mode in 3 Steps

To complete the updating of my 3-part series on Installing and Configuring Snort 3 Beta 3, I now present to you the final chapter in this trilogy: the updated recipe for Snort 3 Inline Bridging Mode in 3 Steps. Snort 3.0 Beta 3 has changed the syntax for creating a new dsrc, so this has been reflected in the new recipe.

Step 1: Add a new function to your snort.lua file
If you followed the updated Snort 3.0 Beta 3 Installation HOWTO, then the default snort.lua file is in /etc/snortsp/snort.lua. Open the file and add the following function:

function bridge (interface1, interface2)
if interface2 == nil then
error("Two interface strings must be specified ( e.g. bridge(\"eth0\", \"eth1\") )")
end
dsrc1 = {name="src1",
type="afpacket",
intf=interface1..":"..interface2,
flags=10,
snaplen=1514,
display="none",
tcp={maxflows=262144, maxidle=30, flow_memcap=10000000},
other={maxflows=131072, maxidle=30, flow_memcap=1000000},
cksum_mode=0x0,
}
dsrc.new(dsrc1)
eng.new({name="e1"})
eng.link({engine="e1", source="src1"})
eng.start("e1")
end

Step 2: Start SnortSP
Start SnortSP using the following command:

sudo snortsp -L /etc/snortsp/snort.lua

SnortSP will start up and read your new snort.lua file. You will then be greeted by the SnortSP Lua shell.

Step 3: Use the bridge() function
In the Lua shell, type the following (replacing eth0 and eth1 with the correct interfaces on your system):

bridge("eth0", "eth1")

Once the bridge is up and running, you can do the following to display packets traversing the bridge:

eng.set_display({engine="e1", display="none"})
Press the Up arrow and change "none" to "classic".
View the output.
Press the Up arrow twice to retrieve the "none" command and press Enter.

When finished, shut down SnortSP by running the following command:

ssp.shutdown()

Integrating Snort 3.0 Beta 3 and Sguil in 3 Steps

Since I updated the "Installing Snort 3.0 Beta on Ubuntu 8.04" post to work with Snort 3.0 Beta 3, here's the update for the "Integrating Snort 3.0 (SnortSP) and Sguil in 3 Steps" post. Since the original post, NSMnow 1.3.5 has been released, so the URL has been updated in the recipe to reflect this new version. Also, there appears to be a bug in the current sspiffy.sh whereby it configures the dsrc type to be "file" instead of "pcap". I added a quick one-liner to correct this in the snort.lua file.

Please note that if you have an existing NSMnow installation, following this recipe may or may not work. This recipe is designed for new NSMnow installations.

The best open source tool to manage Snort alerts is Sguil and the easiest way to install Sguil is using NSMnow. NSMnow automatically installs and configures barnyard2 (compatible with SnortSP's unfied2 format), sancp, Sguil, and Snort 2.x. We're going to replace NSMnow's snort alert process with Snort 3.0.

This quick recipe assumes that you're running on Ubuntu 8.04 and your primary network interface is eth0. You should be able to copy/paste each of the three code blocks into your terminal.

Obligatory disclaimer: I offer no warranty of any kind. If this breaks your box, you get to keep both pieces.

Step 1: Get root privileges

##########################
sudo -i
##########################

Step 2: Install NSMnow

##########################
mkdir /usr/local/src/NSMnow
cd /usr/local/src/NSMnow
wget http://www.securixlive.com/download/nsmnow/NSMnow-1.3.5.tar.gz
tar zxvf NSMnow-1.3.5.tar.gz
./NSMnow -i -y
##########################

Step 3: Configure NSMnow and SnortSP and start

##########################
if ! grep "/nsm/server_data/server1/load" /etc/apparmor.d/usr.sbin.mysqld > /dev/null
then
sed -i 's|}| /nsm/server_data/server1/load/* r,|g' /etc/apparmor.d/usr.sbin.mysqld
echo "}" >> /etc/apparmor.d/usr.sbin.mysqld
fi
/etc/init.d/apparmor restart
/usr/local/sbin/nsm --server --start
/usr/local/sbin/nsm_sensor_ps-start --skip-snort-alert
mkdir /etc/snortsp_alert
cd /etc/snortsp_alert
cp -R /etc/nsm/sensor1/* .
mv snort.conf snort_orig.conf
sspiffy.sh /usr/local -c snort_orig.conf -i eth0
sed -i 's|type="file"|type="pcap"|g' snort.lua
grep -v "sameip" rules/bad-traffic.rules > rules/bad-traffic.rules.2
rm -f rules/bad-traffic.rules
mv rules/bad-traffic.rules.2 rules/bad-traffic.rules
snortsp -C -L snort.lua
##########################

Snort 3.0 is now capturing packets on eth0 and analyzing them. Let's verify that now.

Launch the Sguil client by opening a new terminal and typing the following:

##########################
sguil.tk
##########################

When prompted, login to Sguil using the default credentials:
Username: sguil
Password: password

Next, create some alerts by opening a browser and going to:
http://www.testmyids.com

Finally, go into the Sguil console and you should see two new alerts:


This demonstrates that SnortSP is capturing packets, analyzing them with the Snort 2.8.2 Detection Engine, and outputting in unified2 format, which is then read by Barnyard2 and inserted into the Sguil database.

When finished, return to your SnortSP window and press ctrl-c to terminate the SnortSP process. Then type "nsm --all --stop" to terminate all NSMnow processes.

Installing Snort 3.0 (SnortSP) Beta 3 on Ubuntu 8.04 in 3 Steps

Snort 3.0 Beta 3 was released on April 1. You can read an overview of the changes in Snort 3.0 Beta 3 in the mailing list announcement. For more details on the underlying architectural changes in Beta 3, see Marty Roesch's blog. Thanks to Marty and the rest of the Snort 3 Development Team for their hard work in this release!

Installing Snort 3.0 Beta 3 on Ubuntu 8.04 is almost identical to installing Snort 3.0 Beta 2 on Ubuntu 8.04. However, I did have an issue with the Snort 2.8 Detection Engine not compiling correctly. This turned out to be libtool not liking the fact that /bin/sh was symlinked to /bin/dash instead of /bin/bash. The one-line fix was:

rm /bin/sh && ln -s /bin/bash /bin/sh

(Special thanks to Russ Combs of the SnortSP development team for his assistance with this issue.)

Here's the complete install recipe that worked for me:

Step 1: Get root privileges

##########################
sudo -i
##########################

Step 2: Install dependencies

##########################
aptitude update
aptitude -y install build-essential \
libdumbnet1 libdumbnet-dev \
uuid uuid-dev \
libncurses5 libncurses5-dev \
libreadline5 libreadline5-dev \
libpcap0.8 libpcap0.8-dev \
libpcre3 libpcre3-dev \
liblua5.1-0 liblua5.1-0-dev \
flex bison
##########################

Step 3: Download, compile, and install Snort 3.0 Beta 3

##########################
rm /bin/sh && ln -s /bin/bash /bin/sh
cd /usr/local/src/
wget http://dl.snort.org/snortsp/\
snortsp-3.0.0b3.tar.gz
tar zxvf snortsp-3.0.0b3.tar.gz
cd snortsp-3.0.0b3/
./configure
make
make install
mkdir /etc/snortsp/
cp etc/* /etc/snortsp/
cd src/analysis/snort/
./configure \
--with-platform-includes=/usr/local/include \
--with-platform-libraries=/usr/local/lib
make
make install
ldconfig
##########################