Feeds

The balkanization of Storm Worm botnets

New hope in blocking prolific pest

Securing Web Applications Made Simple and Scalable

Creators of the Storm Worm Trojan have introduced a change to their malware that could help administrators trying to fortify their ISPs and networks against the prolific pest.

PCs infected by Storm in the past week or so use a 40-byte key to encrypt traffic sent through Overnet, a peer-to-peer protocol that helps individual bots connect to other infected machines, according to Joe Stewart, a senior researcher with SecureWorks, a provider of security services and software.

The change effectively segments the Storm botnet, estimated by Stewart to contain from 250,000 to 1 million machines, into smaller networks because each node must know the password to unencrypt the Overnet traffic.

Storm burst on the scene early this year after a flurry of emails carried subjects promising information about a winter storm that was savaging Northern Europe. Many of the recipients ended up getting infected by a Trojan that made their PC part of a network of infected computers. Criminals use such botnets to send spam and carry out distributed denial of service attacks, in which servers are flooded with more data than they can handle.

Since then, Storm has waged a series of ever-changing attacks, including pump-and-dump stock spam, fraudulent e-card messages and emails that promise racy pictures or romance to the lovestruck. The Storm botnet is hard to eradicate using traditional techniques because it relies on P2P technology, rather than connecting through a single command and control server.

New Weapon

The widespread use of encryption would provide a new weapon for administrators to fight back against Storm. Until now, one of the only ways to protect a network from the Trojan was to block all P2P traffic. That was fine for corporations and other organizations, but often proved problematic for ISPs and university networks.

Encrypted Storm traffic looks significantly different than regular P2P traffic sent using the Overnet protocol, making it relatively easy to write firewall rules that block the former while still allowing the latter, Stewart says. A researcher for the Bleedingthreats blog has devised a generic set of signatures that look for certain UDP packet sizes typical of Storm.

The balkanizing of bots into distinct botnets could be a sign that the Storm authors plan to sell services to spammers or other cyber criminals. But so far, there is little evidence such plans are in place, because Storm is only segmenting bots into two groups: those created in the last week and those created earlier.

Stewart says there could be other reasons for breaking bots into smaller groups, such as the desire for more nimble and manageable networks. ®

The smart choice: opportunity from uncertainty

More from The Register

next story
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
How long is too long to wait for a security fix?
Synology finally patches OpenSSL bugs in Trevor's NAS
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
Roll out the welcome mat to hackers and crackers
Security chap pens guide to bug bounty programs that won't fail like Yahoo!'s
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Researcher sat on critical IE bugs for THREE YEARS
VUPEN waited for Pwn2Own cash while IE's sandbox leaked
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.