Per-Analysis Network Routing

With the more advanced per-analysis routing, it is naturally also possible to have one default route - a setup that used to be popular before, when the more luxurious routing was not yet available.

In our examples, we’ll be focusing on KVM as it is our default machinery choice.

Warning

In case if you see proxy IP:PORT in networking for example as tor 9040 port. It happens due that you have installed docker on your host and it breaks some networking filters.

To fix proxy IP:PORT problem, you need to run following script. Save it to file, give execution permission with sudo a+x iptables_fix.sh and run it with proper arguments:

!/bin/bash
# Fix when docker breaks your iptables
if [ $# -eq 0 ] || [ $# -lt 2 ]; then
    echo "$0 <netowrk range> <vir_iface> <real_iface>"
    echo "    example: $0 192.168.1.0 virbr0 eno0"
    exit 1
fi

echo "[+] Setting iptables"
iptables -t nat -A POSTROUTING -o "$2" -j MASQUERADE
iptables -A FORWARD -i "$2" -o "$2" -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i "$2" -o "$2" -j ACCEPT
iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT
iptables -I FORWARD -o "$2" -d  "$1"/24 -j ACCEPT
iptables -t nat -A POSTROUTING -s "$1"/24 -j MASQUERADE
iptables -A FORWARD -o "$2" -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i "$2" -o "$3" -j ACCEPT
iptables -A FORWARD -i "$2" -o lo -j ACCEPT

echo "[+] Setting network options"
# https://forums.fedoraforum.org/showthread.php?312824-Bridge-broken-after-docker-install&s=ffc1c60cccc19e46c01b9a8e0fcd0c35&p=1804899#post1804899
{
    echo "net.bridge.bridge-nf-call-ip6tables=0";
    echo "net.bridge.bridge-nf-call-iptables=0";
    echo "net.bridge.bridge-nf-call-arptables=0";
    echo "net.ipv4.conf.all.forwarding=1";
    echo "net.ipv4.ip_forward=1";
} >> /etc/sysctl.conf
sysctl -p
echo "iptables -A FORWARD -i $2 -o $2 -j ACCEPT" >> /etc/network/if-pre-up.d/kvm_bridge_iptables

virsh nwfilter-list

To make it permanent you can use iptables-save.

Per-Analysis Network Routing Options

Following is the list of available routing options.

Routing Option	Description
None Routing	No routing whatsoever, the only option that does not require the Rooter to be run (and therefore also the default routing option).
Drop Routing	Completely drops all non-CAPE traffic, including traffic within the VMs’ subnet.
Internet Routing	Full internet access as provided by the given network interface (similar to the simple_global_routing setup).
InetSim Routing	Routes all traffic to an InetSim instance - which provides fake services - running on the host machine.
Tor Routing	Routes all traffic through Tor.
VPN Routing	Routes all traffic through one of perhaps multiple pre-defined VPN endpoints.
SOCKS Routing	Routes all traffic through one of perhaps multiple pre-defined VPN endpoints.

Using Per-Analysis Network Routing

Now that you know the available network routing options, it is time to use them in practice. Assuming CAPE has been configured properly taking advantage of its features is as simple as starting the CAPE Rooter and choosing a network routing option for your analysis.

Documentation on starting the Rooter may be found in the CAPE Rooter Usage document.

Both global routing and per-analysis routing require ip forwarding to be enabled:

$ echo 1 | sudo tee -a /proc/sys/net/ipv4/ip_forward
$ sudo sysctl -w net.ipv4.ip_forward=1

Configuring iproute2

For Linux kernel TCP/IP source routing reasons it is required to register each of the network interfaces that we use with iproute2. This is trivial but necessary.

As an example we’ll be configuring Internet Routing (aka the dirty line) for which we’ll be using as example eth0 network interface. You need to replace eth0 with your server main network interface. To get your default network interface you can run:

* ``ip route | grep '^default'|awk '{print $5}'``

To configure iproute2 with eth0 we’re going to open the /etc/iproute2/rt_tables file which will look roughly as follows:

#
# reserved values
#
255     local
254     main
253     default
0       unspec
#
# local
#

Now roll a random number that is not yet present in this file with your dice of choice and use it to craft a new line at the end of the file. As an example, registering eth0 with iproute2 could look as follows:

#
# reserved values
#
255     local
254     main
253     default
0       unspec
#
# local
#

400     eth0

And that’s all there is to it. You will have to do this for each network interface you intend to use for network routing.

None Routing

The default routing mechanism in the sense that CAPE allows the analysis to route as defined by a third party. As in, it doesn’t do anything. One may use the none routing in conjunction with the simple_global_routing.

Drop Routing

The drop routing option is somewhat like a default None Routing setup (as in, in a machine where no global iptables rules have been created providing full internet access to VMs or so), except that it is much more aggressive in actively locking down the internet access provided to the VM.

With drop routing the only traffic possible is internal CAPE traffic and hence any DNS requests or outgoing TCP/IP connections are blocked.

Internet Routing

By using the internet routing one may provide full internet access to VMs through one of the connected network interfaces. We also refer to this option as the dirty line due to its nature of allowing all potentially malicious samples to connect to the internet through the same uplink.

Note

It is required to register the dirty line network interface with iproute2 as described in the Configuring iproute2 section.

InetSim Routing

For those that have not heard of InetSim, it’s a project that provides fake services for malware to talk to. To use InetSim routing one will have to set up InetSim on the host machine (or in a separate VM) and configure CAPE so that it knows where to find the InetSim server.

The configuration for InetSim is self-explanatory and can be found as part of the $CWD/conf/routing.conf configuration file:

[inetsim]
enabled = yes
server = 192.168.122.1

To quickly get started with InetSim it is possible to download the latest version of the REMnux distribution which features - among many other tools - the latest version of InetSim. Naturally, this VM will require a static IP address which should then be configured in the routing.conf configuration file.

We suggest running it on a virtual machine to avoid any possible leaks

Tor Routing

Note

Although we highly discourage the use of Tor for malware analysis - the maintainers of Tor exit nodes already have a hard enough time keeping up their servers - it is a well-supported feature.

First of all, Tor will have to be installed. Please find instructions on installing the latest stable version of Tor here.

We’ll then have to modify the Tor configuration file (not talking about CAPE’s configuration for Tor yet!) To do so, we will have to provide Tor with the listening address and port for TCP/IP connections and UDP requests. For a default KVM setup, where the host machine has IP address 192.168.122.1, the following lines will have to be configured in the /etc/tor/torrc file:

TransPort 192.168.122.1:9040
DNSPort 192.168.122.1:5353

Don’t forget to restart Tor (/etc/init.d/tor restart). That leaves us with the Tor configuration for Cuckoo, which may be found in the $CWD/conf/routing.conf file. The configuration is pretty self-explanatory so we’ll leave filling it out as an exercise to the reader (in fact, toggling the enabled field goes a long way):

[tor]
enabled = yes
dnsport = 5353
proxyport = 9040

Note that the port numbers in the /etc/tor/torrc and $CWD/conf/routing.conf files must match for the two to interact correctly.

VPN Routing

It is possible to route analyses through multiple VPNs. By defining a couple of VPNs, perhaps ending up in different countries, it may be possible to see if potentially malicious samples behave differently depending on the country of origin of their IP address.

The configuration for a VPN is much like the configuration of a VM. For each VPN you will need one section in the $CWD/conf/routing.conf configuration file detailing the relevant information for the VPN. In the configuration, the VPN will also have to be registered in the list of available VPNs (the same as you’d do for registering more VMs).

Configuration for a single VPN looks roughly as follows:

[vpn]
# Are VPNs enabled?
enabled = yes

# Comma-separated list of the available VPNs.
vpns = vpn0

[vpn0]
# Name of this VPN. The name is represented by the filepath to the
# configuration file, e.g., CAPE would represent /etc/openvpn/cuckoo.conf
# Note that you can't assign the names "none" and "internet" as those would
# conflict with the routing section in cuckoo.conf.
name = vpn0

# The description of this VPN which will be displayed in the web interface.
# Can be used to for example describe the country where this VPN ends up.
description = Spain, Europe

# The tun device hardcoded for this VPN. Each VPN *must* be configured to use
# a hardcoded/persistent tun device by explicitly adding the line "dev tunX"
# to its configuration (e.g., /etc/openvpn/vpn1.conf) where X in tunX is a
# unique number between 0 and your lucky number of choice.
interface = tun0

# Routing table name/id for this VPN. If table name is used it *must* be
# added to /etc/iproute2/rt_tables as "<id> <name>" line (e.g., "201 tun0").
# ID and name must be unique across the system (refer /etc/iproute2/rt_tables
# for existing names and IDs).
rt_table = tun0

Note

It is required to register each VPN network interface with iproute2 as described in the Configuring iproute2 section.

• Helper script, read code to understand it
• Example of wireguard integration

VPN persistence & auto-restart source:

1. Run the command:
    # sudo nano /etc/default/openvpn`
    and uncomment, or remove, the “#” in front of AUTOSTART="all"
    then press ‘Ctrl X’ to save the changes and exit the text editor.

2. Move the .ovpn file with the desired server location to the ‘/etc/openvpn’ folder:
    # sudo cp /location/whereYouDownloadedConfigfilesTo/Germany.ovpn /etc/openvpn/

3. In the ‘/etc/openvpn’ folder, create a text file called login.creds:
    # sudo nano /etc/openvpn/login.creds
    and enter your IVPN Account ID (starts with ‘ivpn’) on the first line and any non-blank text on the 2nd line, then press ‘Ctrl X’ to save the changes and exit the text editor.

4. Change the permissions on the pass file to protect the credentials:
    # sudo chmod 400 /etc/openvpn/login.creds

5. Rename the .ovpn file to ‘client.conf’:
    # sudo cp /etc/openvpn/Germany.ovpn /etc/openvpn/client.conf

6. Reload the daemons:
# sudo systemctl daemon-reload

1. Start the OpenVPN service:
    # sudo systemctl start openvpn

2. Test if it is working by checking the external IP:
    # curl ifconfig.co

3. If curl is not installed:
    # sudo apt install curl

SOCKS Routing

You also can use socks proxy servers to route your traffic. To manage your socks server you can use Socks5man software. Building them by yourself, using your favorite software, bying, etc The configuration is pretty simple and looks like VPN, but you don’t need to configure anything else

Example:

[socks5]
# By default we disable socks5 support as it requires running utils/rooter.py as
# root next to cuckoo.py (which should run as regular user).
enabled = no

# Comma-separated list of the available proxies.
proxies = socks_CC

[socks_CC]
name = CC_socks
description = CC_socks
proxyport = 5000
dnsport = 10000