This morning, the Directorate for Combating Organized Crime and Terrorism (DIICOT) in Romania conducted 42 raids, identifying 32 people specializing in VoIP hacking.
Numbers so far is 11,5 million euros in fraudulent VoIP traffic from this group. The group made around 10% of this amount from their premium numbers.
The main technique seemed to establish premium numbers in Sierra Leone, Somalia, Austria, Latvia, North Korea, Zimbabwe, Madagascar, Belarus, etc and cash in on calls to these destinations.
This correlates to attacks we have seen, calls trying to go to Somalia and Sierra Leone on our VoIP honeypots (but of course they were not successful).
This only confirms that there are major money in VoIP hacking and this is not single persons doing it but organized crime. I’m afraid this is just the beginning.
Original link
Link translated to English
Sandro Gauci has written more about it here