Feeds

RUSTOCK TAKEDOWN: How the world's worst botnet was KO'd

Redmond posse sends bot-herd cowboys a-runnin'

Choosing a cloud hosting partner with confidence

Analysis The unidentified criminals behind the infamous Rustock botnet were paying at least $10,000 a month for US-based command and control servers prior to a successful takedown operation last week.

Instead of using bulletproof hosting outfits (rogue ISPs normally based in eastern Europe) that ignore takedown notices, the botherders behind Rustock attempted to hide in plain sight...

Alex Lanstein, a security analyst at FireEye Malware Intelligence Labs, who worked with Microsoft on the successful takedown operation, credits the tactic as being the main reason why Rustock stayed in operation for more than five years.

Rustock, which spread largely via drive-by download from compromised websites, turned compromised machines into spam-spewing monsters. At its peak, the botnet was responsible for almost the worldwide production of spam. Much of this junk mail promoted sites selling unlicensed pharmaceutical drugs, such as Viagra. With the closure of the world's largest spam affiliate program – spamit.com – back in October, this volume of junk mail dropped slightly. This was essentially because one of the botnet owner's main clients had shut up shop, but Rustock was still responsible for at least 30 per cent of global spam.

The dismantling of the core network of around 26 servers that were used to control infected clients meant that this spam torrent suddenly trickled away to nothing last Wednesday.

Rustock: My part in its downfall

The operation to mount the takedown began nine months previously, when Microsoft held a conference call with security partners. During the call, Rustock emerged as one of the primary threats facing Redmond's customers. A loose-knit committee focusing on dismantling Rustock was formed which, over time, divided itself into four organisations as other security researchers dropped out to tackle other projects. The four groups included representatives from Microsoft itself, along with staff from pharmaceutical giant Pfizer, as well as security researchers from FireEye and computer scientists from the University of Washington.

Lanstein, who had previously worked on the takedown of the Mega-D and Szerbi botnets, told El Reg that the pooling of resources was necessary because Rustock was a more sophisticated threat and everyone had only part of the overall jigsaw. "Everyone learned from each other," he explained.

Compromised machines were infected with malware packed via custom encryption techniques that made it look like a .rar compressed archive file. Each machine communicated with control nodes via posts that, to a casual observer, would look like posts to a bulletin board or web forum. In addition, the command and control servers were all US-based and mostly located with small hosting firms who had no idea that anything was amiss... and not the specialist cybercrime-friendly hosting facilities in eastern Europe beloved by most cybercrime gangs.

Using this approach, the Rustock botnet herders were largely able to keep their systems off the radar of collaborative anti-spam and net security efforts run by the likes of Spamhaus and Shadowserver.

FireEye was able to fingerprint what communication between zombie clients and the command nodes of the Rustock network looked like. In this way it was able to identify the main command nodes and backup servers used by Rustock.

Microsoft is operating sinkhole servers for Rustock command and control domains so they are able to identify PCs compromised with botnet software, providing more useful raw intelligence on the zombie network in the process.

Internet Security Threat Report 2014

Next page: Legal precedents

More from The Register

next story
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Edward who? GCHQ boss dodges Snowden topic during last speech
UK spies would rather 'walk' than do 'mass surveillance'
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
NOT OK GOOGLE: Android images can conceal code
It's been fixed, but hordes won't have applied the upgrade
Apple grapple: Congress kills FBI's Cupertino crypto kybosh plan
Encryption would lead us all into a 'dark place', claim G-Men
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.