Thousands lost in rising VoIP attacks

Tagged: VoIP, Technology
Source: - Read the full article
Posted: 6 years 2 weeks ago

"Australian network companies have told of clients receiving phone bills including $100,000 worth of unauthorised calls placed over compromised VoIP servers. Smaller attacks have netted criminals tens of thousands of dollars worth of calls. A Perth business was hit with a $120,000 bill after hackers exploited its VoIP server to place some 11,000 calls over 46 hours last year. VoIP networks are a cash cow for criminals who can earn money from unscrupulous telecommunications carriers profiting from calls placed over victim's networks or to ramp up calls to premium numbers..." | more



GraysonPeddie's picture
Joined: 10/29/2006
Posts: 570

Hmmm... There are several things that I do since I live in US:

#1: Strong passwords, consisting of upper case letters, lower case letters, numbers, and symbols.

#2: Restrict the number of extensions (that I have) to a select number of private IP addresses. Limit remote extensions if possible. VPN with very strong password is recommended. In my case, I use PPTP (pptpd in Ubuntu Server 10.04.1) and it is farily easy to setup, but it is less secure than OpenVPN (I don't have the links to proove it, but that's AFAIK). Then, you can close port 5060 in your firewall.

#3: Restrict outgoing calls. In my case, I only allow 1-777 phone numbers (I'm with CallCentric), 1-850 numbers, and 1-407 numbers. I block international calling in my server and my CallCentric account.

#4: Keep your VoIP server and all your software (packages in Linux) up-to-date.

#5: If you're using Linux, there are "three-strikes-and-you're-out" programs out there that monitor for unsuccessful logins. One example is fail2ban and I'm using it in combination with FreeSWITCH (

#6: If you're using CallCentric with auto-recharge, there are settings available in CallCentric that allows you to limit the number of times when auto-charge kicks in. For me, I don't bother with that, because when I don't make and receive phone calls a lot, I just leave it off. Money is very precious for me, because if my VoIP server gets hacked, I'd be very disappointed and be faulted for not securing my VoIP server properly, so I'm glad that I'm keeping my server protected.

But the whole point of the article is that businesses and consumers don't want to bother with securing their VoIP servers and that tells me they're asking to get their server(s) hacked. It's not a valid excuse not to secure your VoIP server to safeguard your investment.

PC: Tt Core V21; Kaveri APU, 16GB RAM, GTX 960, Arch Linux
Server: Rosewill Legacy V6-S, AMD Athlon 5350 APU, 8GB RAM, 90W DC-IN PSU, Ubuntu Server