SIP Vicious (Hey Hey, My My)

Despite the fact that I was an impressionable young college student during the height of the punk rock movement, I was never much of a fan of the genre. While I enjoyed a few songs by the Clash and some of the more obscure punk bands like Eddie and the Hot Rods (yes, they were a real group), I generally preferred a less chaotic sound. So, despite being surrounded by legions of Ramones fans and pretending to be just as hip as they were, I secretly listened to Paul McCartney sing “Silly Love Songs.” That probably explains why I eventually traded in my Gibson Les Paul electric guitar for a tenor ukulele.

Of all the punk bands that were popular with my university peers, the one that I could never stand was the Sex Pistols.   While I have no problem with loud, they were just plain noisy. Their lead singer (and I use that term loosely) was a bloke that went by the name of Johnny Rotten. He was out-of-tune, out-of-time, and just plain, well, rotten.

Alongside Mr. Rotten was the band’s bass player, Sid Vicious. However, Sid is possibly more famous for killing his girlfriend, Nancy, than for any music he might have made in his short life.

So, what does this have to do with unified communications? Well, it just so happens that the most popular SIP “hacker” tools goes by the name of SIP Vicious and despite its reference to a heroin addicted murderer, you will want to throw this one on the turntable and give it a spin.

SIP Vicious

SIP Vicious is a collection of freeware tools that can be used to test many of the vulnerabilities of your SIP platform. Specifically, it consists of these four modules:

  • svmap – This is a sip scanner. It lists SIP devices found within an IP range.
  • svwar – This module identifies active extensions on a PBX.
  • svcrack – This is an online password cracker for a SIP PBX.
  • svreport – This module manages sessions and exports reports in various formats.
  • svcrash – This module attempts to stop unauthorized svwar and svcrack scans.

Of these, allow me to spend a little time on svcrack.

In my recent blog article, Communications Security: Covering the Bases, I wrote of  how weak telephone passwords can lead to toll fraud. This table shows you the maximum time it would take a hacker to break into an unprotected system.

A 4-digit pin (0000-9999) can be hacked in 142 seconds.

A 5-digit pin (00000-99999) can be hacked in 23.8 minutes.

A 6-digit pin (000000-999999 can be hacked in 3.9 hours.

A 7-digit pin (0000000-9999999) can be hacked in 1.6 days.

An 8-digit pin (00000000-99999999) can be hacked in 2.3 weeks.

By running svcrack against a system that uses 4-digit telephone pins, a 14-year-old kid can register a SIP device in two minutes or less. Of course, it probably won’t be a 14-year-old kid, but someone who is in the business of stealing long distance minutes from unsuspecting companies. I’ll let you do the math to figure out how long it takes to rack up a $10,000 bill for calls to Colombia.

Now, just because the bad guys use SIP Vicious, don’t think that you can’t do the same. SIP Vicious is freeware so there is nothing stopping you from downloading your own copy and exercising the security aspects of your system. Don’t limit yourself to svcrack, though. Play with all the different components to determine how they impact your SIP solution. Believe me, the hackers will be doing that without your knowledge or permission.

SIP Vicious Download

Note:  SIP Vicious is a collection of Python scripts.  If you haven’t already done so, you will need to download and install Python.

An example svcrack invocation will look similar to this: -u 3000 -d passwords.txt

3000 is the extension you want to register against, passwords.txt contains the passwords you want to attempt, and is the IP address of the SIP server you want to break into.

The script will cycle through all the entries in the passwords file until it runs out of passwords or bingo, the REGISTER succeeds.

Take Control of Your Destiny

There is nothing stopping you from implementing strong protection to prevent those SIP Vicious attacks from doing any harm.  Here a a few easy steps that any enterprise can take.

  • Increase the number of digits used for your telephone passwords. I strongly suggest that you get your users accustomed to nothing less than 8-digits. That’s the number I use on my SIP devices today.
  • Follow best practices for those passwords. Although you are limited in what you can do with digit-only passwords, implement software that ages those passwords and prevents users from reusing the same ones over and over again.
  • Ingress and egress all your remote traffic through a session border controller (SBC). Make sure that your SBC is one that recognizes SIP Vicious and can neutralize malicious registration attacks.
  • Avaya administrators may want to configure Session Manager firewall policies to rate limit the number of registration attempts that a SIP user agent can send within a given time period.  Be careful that any policy you set does not preclude an SBC from propagating REGISTER requests from remote clients.

Recognize and mitigate threats before you are hit with toll fraud or the theft of your communications data. SIP Vicious is a set of tools that can both harm and help.  Thankfully, you get to choose how it will be applied to your SIP platform.


  1. Sandra Baker · · Reply

    Where do you install these?

    1. On a PC. You then run the tests against your SIP system.

  2. Great post. Today i learned New topics, Thank you Andrew

    1. Thanks. It was a fun one to write.

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