Feeds

Kelihos botnet BACK FROM THE DEAD

Bloodied spam-spewing zombie staggers in

Using blade systems to cut costs and sharpen efficiencies

The spam-spewing Kelihos botnet has returned from the dead.

Microsoft collaborated with Kaspersky Lab to run a successful takedown operation last September. The takedown decapitated the botnet by shutting down command-and-control server nodes, directing the bots on infected computers to contact a server under the control of security researchers, rather than one controlled by the attackers.

In the case of the Kelihos peer-to-peer botnet, Kaspersky researchers pushed out a new peer address, which the existing infected PCs began polling for new instructions.

This "sink-holing" action meant that compromised machines in the network were no longer receiving instruction and spam templates every time they "phoned home" to command nodes. Even so the machines were still infected and left with an open back door that might be exploited by cybercrooks. A deliberate decision was taken NOT to patch infected machines, a problematic process that's illegal in some countries. Instead it was left to users to fix the security on their compromised machines.

Almost inevitably many didn't bother.

Over time miscreants have used the botnet's complex back-channel network of proxy servers to regain control of compromised machines. These machines have been infected with a new variant of Kelihos that uses modified encryption schemes and algorithms to mask communication. Two different keys are being used, suggesting that more than one gang is controlling the botnet, according to a new analysis Maria Garnaeva, a security researcher with Kaspersky Lab.

""As you can see, two different RSA keys are used within a tree which makes us think that probably two different groups are in possession of each key and are currently controlling the botnet," Garnaeva explains.

"Our investigation revealed that the new version appeared as early as September 28, right after Microsoft and Kaspersky Lab announced the neutralisation of the original Hlux/Kelihost botnet," she added.

At its peak, Kelihos spewed out as many as 4 billion junk mail messages, spam-vertised unlicensed pharmaceuticals, stock scams and other tat from around 45,000 malware-infected zombie PCs. Current spam levels are nowhere near this bad, even though they still pose a problem.

The reappearance of spam from the botnet underlines that sinkholing alone is not effective in killing off botnets. Security experts knew this even at the start. Garnaeva suggests that only patching infected machines or taking botnet controllers out of circulation would be truly effective.

Last week Microsoft filed an amended lawsuit alleging that a Russian national was involved in both creating the original Kelihos malware and running the botnet network. Andrey Sabelnikov of St Petersburg, a software developer and former employee at two Russian security firms, denies any wrongdoing. ®

The smart choice: opportunity from uncertainty

More from The Register

next story
Yorkshire cops fail to grasp principle behind BT Fon Wi-Fi network
'Prevent people that are passing by to hook up to your network', pleads plod
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
NEW, SINISTER web tracking tech fingerprints your computer by making it draw
Have you been on YouPorn lately, perhaps? White House website?
LibreSSL RNG bug fix: What's all the forking fuss about, ask devs
Blow to bit-spitter 'tis but a flesh wound, claim team
Black Hat anti-Tor talk smashed by lawyers' wrecking ball
Unmasking hidden users is too hot for Carnegie-Mellon
Attackers raid SWISS BANKS with DNS and malware bombs
'Retefe' trojan uses clever spin on old attacks to grant total control of bank accounts
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
prev story

Whitepapers

Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
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.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.