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T H E J O K E R - B.A.T.M.A.N.'s arch nemesis

Introduction

The Joker uses libpcap to write raw Ethernet data onto an interface running in Ad-Hoc mode, and relies on the system to support source address spoofing.
Note, that a version of B.A.T.M.A.N. was used before the TVLV Concept and Translation Tables were introduced (git revision c7fb52999 or maybe older) when developing The Joker.
However, The Joker techniques may be aligned to current versions.
Moreover, the types of penetration tests may be aligned to other routing protocols besides B.A.T.M.A.N. as well.

Download

Release tarballs as well as snapshots are available:

  • git web directory: https://git.open-mesh.org/joker.git
  • git download: git clone git://git.open-mesh.org/joker.git
  • snapshot:https://git.open-mesh.org/joker.git/snapshot/refs/heads/main.tar.gz

Usage

 ./joker -i <interface> [other options]

General options

-i <interface>

Select the Interface that is connected to the BATMAN network
-m <mac-addr>

Use this MAC Address instead of your real one (Format: 00:11:22:33:44:55)
-h <mac-addr>

Use this HNA Address instead of the default one (00:33:11:33:33:77)
-r <mac-addr>

(Blackhole only) Make this neighbor responsible for the black hole.
(Current BATMAN version filters non-broadcasts messages and this doesn't work!)
-t <time>

(Loop) Specify the waiting time between each packet in milliseconds.
(Fuzz) Specify the time to sniff for available MAC addresses in seconds.
-v

(Flood) Use STA flooding instead of route flooding
(Fuzz) If given a mutation-based fuzzing is executed (otherwise random packets)

Penetration tests:

-f

Starts a Flooding penetration test. First a fake node is announced in the network, and after 30 seconds,
huge amounts of random Routes and HNAs via this node are published.
If -v is specified, new Ad-Hoc Stations are created. Both tests may lead to memory exhaustion
and bandwidth consumption in the whole network. WARNING: This includes crashes and lockups!
-l

Tries to create loops. In this mode The Joker listens if a node forwards an incoming 3 or more
hop route, and its predecessor will be told the destination can be reached directly over the
forwarding node. This creates Loops and lets incoming packets time out due to TTL becoming 0.
This test is rather unstable and possibly needs tweaking with -t (Default: 500 ms)
-b

Creates a black hole. Use -r to make some neighbor responsible by only forwarding the fake
routes to it instead of broadcasting. (-r does not work, BATMAN filters those packets.)
-z

Start a random fuzzing test after sniffing for available MAC addresses.
Either run a standard fuzzing, where joker collects Target addresses for -t seconds,
Or run a mutation-based fuzzing test using incoming packets with -v

Run

make
./joker

Tests

Peer/Route Flooding

The Joker starts a Flooding penetration test by announcing a new node and waiting several seconds before flooding false so called Originator Messages (OGM).
The Route Flooding test may be combined with an unlimited number of peers so that The Joker penetration test model still has room for improvement to intensify the Flooding penetration test.
B.A.T.M.A.N. nodes do not simply forward those falsified routing messages but they collect and accumulate them and also drop excessive routing information.
These falsified routes do only propagate slowly throughout the network.
The critical resource is every node’s route memory and CPU power needed for route lookups.
B.A.T.M.A.N. allocated memory is limited for routing information, thus limiting the impact of the penetration test.
Still measurable impact on the network may be noticed when excuting the Flooding.

Blackhole

When using the Blackhole test, The Joker turn a node into a Blackhole, that listens for incoming Originator Messages.
Afterwards, the messages will be modified to have the best possible link metric to any destination in the network, and subsequently be forwarded as usual.
As a result, those falsified messages propagate through the network.
Finally all routes are diverted to the Blackhole.
No communication in the network may be possible anymore.

Loop Forming

To create loops in B.A.T.M.A.N. networks, The Joker listens for Originator Messages where the Direct Link Flag is not set, meaning the sender of this OGM is not its originator.
The Joker injects a network packet with the spoofed source address of the sender back to the predecessor of this message with a reverse route and perfect metric.
Luckily the spoofed node does not see this fake OGM, since the mac80211 stack and the receive handlers in B.A.T.M.A.N. do both filter out messages with the source address being the local hardware address.
Thus we can inject packets that will only be processed at one of the two communicating nodes, which makes the establishment of the routing loop possible.
Additionally, the early filtering makes detection of these loops rather hard, since there are no warnings emitted into userspace.
The Loop Forming test results in breaking communication at specific location of the network and in selectively isolating parts from the infrastructure.

Fuzzing

Additionally a Fuzzing penetration test, not targeting the protocol's routing but rather its implementation and underlying code,
is supported by The Joker to cover further resilience tests.

From time to time kernel crashes occured in our tests that point to a driver bug in the Atheros ath5k wireless driver.
Sometimes the malformed packets are spread through the entire network, leading to crashes on several nodes.
The B.A.T.M.A.N. protocol implementation seems not to be affected by any of the randomly modified and malformed packets of The Joker's Fuzzing.

Conclusion

This work builds a base for further research to improve the resilience of routing protocols.
Since B.A.T.M.A.N. has a limitation for maximum routing information, it showed a very good performance and stable connections while executing the Flooding tests.
Blackhole and Loop Forming broke the connections in our test, but related to all three penetration test vectors B.A.T.M.A.N. recovered fast from the impact.

Authors