Botnets getting harder to kill

HotBots conference calls attention to the recent evolution of peer-to-peer botnets

In their current form, botnets are bad enough, but they are quickly evolving into a much tougher species to kill, according to security researchers.

At a conference called HotBots, in Cambridge, Massachusetts -- the first Usenix conference devoted to botnets -- researchers from three U.S. institutions last week presented a paper highlighting the recent evolution of peer-to-peer botnets.

The paper, "Peer-to-Peer Botnets: Overview and Case Study", was written by Julian Grizzard of The Johns Hopkins University Applied Physics Laboratory, Vikram Sharma, Chris Nunnery and Brent ByungHoon Kang of the University of North Carolina at Charlotte, and David Dagon of the Georgia Institute of Technology.

Currently, most botnets use a centralized command-and-control structure based on IRC, partly because there is such a deep existing body of knowledge and code base around the technology. But their centralized structure makes them relatively easy to shut down -- a fact that hasn't stopped crooks from using them to take over large portions of the Internet.

Peer-to-peer (P2P) botnets are another matter. Taking their inspiration and underlying technology from the same P2P networks used to exchange files, they have no centralized control point, making them much harder to detect and shut down, the researchers said.

These botnets are an emerging phenomenon, but have already made a big impact. For their case study the researchers chose the botnet implanted by the Storm worm, called Trojan.Peacomm. Trojan.Peacomm first made an impact in January, but also had a major re-emergence last week.

IRC bots go back to 1993 in the case of the benevolent EggDrop bot, and 1998 in the case of GTbot and its variants, one of the first malicious botnets, the researchers said.

A turning point came in 2002 with the first Agobot variants. "Agobot variants are possibly one of the most widespread bots due to its well designed and modular code base," the researchers wrote. "In our opinion, Agobot marks a turning point in which botnets have become a more significant threat."

Gnutella emerged as the first fully decentralized P2P protocol in 2000, and several other such protocols have been developed since then. Trojan.Peacomm uses the Overnet network, which implements the Kademlia algorithm.

Overnet was originally set up to service file-sharing clients such as eDonkey 2000, and while Overnet's own resources were shut down in late 2006 as a result of legal actions, Overnet clients, being completely decentralized, can still function.

Trojan.Peacomm is distributed through email worms, and once installed, goes through a bootstrap process to become part of the Overnet network. To do this the client uses a list that appears to be Overnet nodes likely to be online.

This could be one centralized way of stopping the node from activating, the researchers noted, but since the list includes 146 nodes it could be difficult to ensure all of them are offline.

The node then uses pre-set keys to search for and download a value from the Overnet network. The value is an encrypted URL which points to the location of more files that can be downloaded, fully setting up the node with communications and attack tools.

How to counteract this sort of system? That is proving to be highly difficult so far, the researchers said.

Besides use of the bootstrap list of nodes, the researchers are studying the use of index poisoning as a way of attacking P2P botnets. Index poisoning was first mooted as a way of stopping exchange of copyrighted files, but that isn't its only use, the researchers said.

"Index poisoning could be used in order to slow the infection rate of the bot or possibly to measure the number of bots infected," they wrote.

Join the newsletter!


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.

Matthew Broersma
Show Comments

Brand Post

Shining a light on creativity

MSI has long pushed the boundaries of invention with its ever-evolving range of laptops but it has now pulled off a world first with the new MSI Creative 17.

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers


This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang


It really doesn’t get more “gaming laptop” than this.

Jack Jeffries


As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr


The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?