SS7 Pentesting Toolkit: ss7MAPer

SS7 Pentesting Toolkit

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     The toolkit is build upon the Osmocom SS7 stack and implements some basic MAP messages. At its current state tests against the HLR are ready for use, in future versions tests against VLR, MSCand SMSC will follow. The tool is written in Erlang; to get it running you will need the Erlang runtime environment. It is developed for version 17.5.

Signalling System No. 7 (SS7) is a set of telephony signaling protocols developed in 1975, which is used to set up and tear down most of the world’s public switched telephone network (PSTN) telephone calls. It also performs number translation, local number portability, prepaid billing, Short Message Service (SMS), and other mass market services.

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    As you can see in the picture, the demonstrated test cases for the HLR respond to most of the MAP messages regardless the fact that we are not registered as valid provider. The tool is not configured as a serving MSC nor a roaming contractor. Some of the information gathered can be seen as critical, as the MSISD -> IMSI resolution, the over-the-air crypto keys or the ability to create supplementary services e.g. call forwarding.

The messages and test cases are gathered from public SS7 research of the last years (see 1, 2) and check for known weaknesses in the SS7 domain. The tool itself was developed under a cooperation with the Belgium provider Proximus and aims to test the secure configuration of the internal and external SS7 network access. Thanks a lot for giving us the opportunity here, we are convinced that the tool gives the research community but also telecommunication providers a new, important and (especially) open-source-based possibility for SS7 testing.

Get it running

You will need:

• Erlang. Get it from your repo or from http://www.erlang.org
• Rebar. Get it from your repo or from https://github.com/rebar/rebar
• The code (;

  git clone https://github.com/ernw/ss7MAPer   
  

• The dependencies

  cd ss7MAPer   
  rebar get-deps   
  

• Patch the dependencies

  cd deps/osmo_map   
  patch -p1 < ../../patches/osmo_map.patch   
  cd ../osmo_sccp   
  patch -p1 < ../../patches/osmo_sccp.patch   
  cd ../osmo_ss7   
  patch -p1 < ../../patches/osmo_ss7.patch   
  

• Get the deps to build (; This is not as easy as it might sound, I needed to:
  Patch the epacp/rebar.config and replace

  {port_envs, [   
    {"DRV_CFLAGS", "-g -Wall $ERL_CFLAGS"},   
    {"DRV_LDFLAGS", "-lpcap $ERL_LDFLAGS"}   
  ]}.   
  

  with

  {port_envs, [   
    {"CFLAGS", "-g -Wall $ERL_CFLAGS"},   
    {"LDFLAGS", "-lpcap $ERL_LDFLAGS"}   
  ]}.   
  

  Another dependency is not covered by rebar, so you need to fetch it manually:

  cd deps   
  git clone http://cgit.osmocom.org/erlang/signerl/   
  

  Build the ASN.1 source files:

  cd deps/signerl/TCAP/asn_src/ITU   
  make   
  

  Copy the ASN.1 files to osmo_sccp:

  cp deps/signerl/TCAP/asn_src/ITU/*rl deps/osmo_sccp/src/   
  

  Also the osmo libs have dependencies on each other and some other deps are shared, so I created some symlinks:

  mkdir deps/osmo_sccp/deps   
  ln -sd ../../osmo_ss7 deps/osmo_sccp/deps/osmo_ss7   
  ln -sd ../../epcap deps/osmo_sccp/deps/epcap   
  ln -sd ../../pkt deps/osmo_sccp/deps/pkt   
  ln -sd ../../signerl/MAP deps/osmo_sccp/deps/MAP    
  ln -sd ../../signerl/SCCP deps/osmo_sccp/deps/SCCP   
  ln -sd ../../signerl/TCAP deps/osmo_sccp/deps/TCAP   
  mkdir deps/osmo_map/deps   
  ln -sd ../../osmo_ss7 deps/osmo_map/deps/osmo_ss7   
  ln -sd ../../epcap deps/osmo_map/deps/epcap   
  ln -sd ../../pkt deps/osmo_map/deps/pkt   
  

  And copy some files in place:

  cp deps/signerl/SCCP/itu/include/sccp.hrl deps/osmo_sccp/src/   
  cp deps/signerl/TCAP/include/tcap.hrl deps/osmo_map/src/   
  

• Build the code

  rebar co   
  

The config file

The config file is split in 4 section, sctp, m3ua, sccp and target.

In the sctp section source and destination ip as well as source and destination port of the SCTP connection are configured.

In the m3ua section all the M3UA parameters, like local and remote point code are configured.

In the sccp section currently only the local (or source) global title needs to be configured.

Last but not least in the target section information about the tested environment need to be configured, like the global title of the HLR, or the MSISDN of the tested phone.

Be sure to modify it to your needs.

Running the tool

To run the tool one needs to start a rebar shell:

cd ss7MAPer   
rebar shell   

Then the SIGTRAN connection needs to be established:

Pid = ss7test_app:start(1, "./configfile").   

If everything is set up correctly the m3ua connection comes up.

To run the HLR tests, simply enter:

Pid ! {test_hlr}.   

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