New version of Skype now harder to detect

Version 3.0 harder to detect on network traffic

Skype-blocking companies have been scrambling to update their products after the recent release of a new version of the software that is even harder to detect and block.

The beta of version 3.0 was made available only two weeks ago and, as expected, the client has been re-engineered to make its presence on network traffic tougher to spot, according to leading Skype-blocking outfit iPoque.

There have been a number of subtle but important alterations in 3.0, including a change to the way the client opens encrypted UDP channel to other clients, as well as to the packet lengths themselves. Since the software was already extremely hard to detect, and uses an encrypted channel once calls have been started, blocking filters have depended on tracing small but telltale patterns such as this.

The software also appeared to have been overhauled to make it less likely that intrusion prevention systems (IPSs) unable to properly identify Skype would classify its traffic as "bad" by lowering the number of TCP connections the client attempts to open. This would avoid triggering TCP thresholds set on such systems, said iPoque CEO Klaus Mochalski.

Some of the changes only work if clients at both end of the connection are using version 3.0. The need to maintain backwards compatibility meant that a new client connecting to an older version would make the connection using older and blockable patterns.

The company had now revised its detection algorithms to take account of the changes, he said. The problem was now less detecting Skype as avoiding mis-identification, which could create problems of its own.

"This time we had a hard time to find a pattern and not create false positives [at the same time]," said Mochalski. Despite this, the changes from version 2.5 to 3.0 had not been as significant as those from version 2.0 to 2.5, he indicated. In the longer run, it would be difficult for Skype to change so as to hide completely because it always had to release new software that maintained backwards compatibility.

Germany-based iPoque markets hardware-based systems for detecting and blocking a range of unauthorized software from use on corporate networks, including Skype and notorious P2P systems such as BitTorrent.

There are other ways to block Skype, the simplest being to detect the presence of the client executable on the PC and stop it running in the first place. The tool offered by Sophos does this for nothing but needs the presence of the Sophos anti-virus client -- into which its plugs -- to work.

This mini-war has been raging for some time with previous versions of the software using increasing levels of stealthiness to hide themselves from detection systems, mostly used by rival ISPs and governments. Many corporates, sensitive of data leakage, also have an urgent need to stop it.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

John E. Dunn

Techworld.com
Show Comments

Father’s Day Gift Guide

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?