Kenneth G. Hartman bio photo

Kenneth G. Hartman

Security Consultant,  
Forensic Analyst & 
Certified SANS Instructor

Email Twitter GitHub

The following excerpt is a thread from a discussion on LinkedIn in the Information Security Community group. This discussion was the impetus for my article Is Skype Secure?  which includes an assessment of Skype Security Risks and an assessment methodology.


  • Anybody using Skype yet at an enterprise level? If so, what changed your mind about the “vulnerabilities” claimed to be associated with it?
  • Is Skype secure for business?
  • Is Skype Safe?

Ken Hartman:

My biggest concern with using Skype in the enterprise is the number of peer to peer connections that it makes when the software is launched. To see what I mean, type the command “netstat –no” at the command line before and after launching Skype.

Skype has posted an independent security review at which covers the secure design considerations and touts its usage of encryption. However, I am uncomfortable with multiple encrypted p2p connections to IP addresses across the globe. To see what I mean use the “nslookup” command at the command line on some of the connections reported by netstat as being created by the Skype process ID.

There is a fairly interesting analysis of the Skype Protocol at that explains how the peer to peer connections seem work, but the paper was published in 2004, so it may be not have the most up to date information.

For enterprise communications, I personally prefer a communication product that uses a centralized server that I can control–such as Microsoft Office Communications Server (now called “Lync”) because I can also control the traffic to and from it.

It will be quite interesting to see what Microsoft does with Skype.


@Kenneth — Your points are valid certainly. But, the cost MS OCS is certainly non-trivial as well. If you implement OCS, you have to deal with redundancy and single-point of failure issues as an engineered solution. The hardware alone on this type of implementation ran $1.2M for one of my clients last year. Sure these kinds of consulting projects makes us consultants smile, but you can certainly understands why many organizations would opt for Skype instead of spending this level of cost when they could get Skype for free!

Ken Hartman:

Point well taken regarding the TCO and I know that “Free” is certainly alluring. I use Skype and I like it, but I use it in my home office on a virtual machine. Since “you cannot secure what you do not understand,” I just wanted to call to everyone’s attention that Skype uses a proprietary, encrypted protocol that connects to multiple servers based in multiple foreign countries. As security professionals, we must do a risk assessment in addition to doing a cost-benefit analysis and of course it depends on the type of data your enterprise is trying to protect. Some organizations may accept the risk, but it’s about making informed decisions. Other organizations may feel that their enterprise is more secure if they have more control over the communication technology used. Many regulated businesses need to monitor and log the communications leaving their business. For those organizations, Skype may not be acceptable, but open source technologies that they can fully control probably are. I would love to hear from other folks who have made a policy decision regarding Skype and what they opted instead.


@Kenneth - Roger, that…I think anybody using Skype does not have a security policy in mind. They’re using it for the sheer convenience of a “FREE” phone call, or low cost international service, and the video conferencing capability. It’s all about convenience; not about security.