Feeds

Kelihos botnet BACK FROM THE DEAD

Bloodied spam-spewing zombie staggers in

Providing a secure and efficient Helpdesk

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. ®

Choosing a cloud hosting partner with confidence

More from The Register

next story
SMASH the Bash bug! Apple and Red Hat scramble for patch batches
'Applying multiple security updates is extremely difficult'
Shellshock: 'Larger scale attack' on its way, warn securo-bods
Not just web servers under threat - though TENS of THOUSANDS have been hit
Apple's new iPhone 6 vulnerable to last year's TouchID fingerprint hack
But unsophisticated thieves need not attempt this trick
Hackers thrash Bash Shellshock bug: World races to cover hole
Update your gear now to avoid early attacks hitting the web
Oracle SHELLSHOCKER - data titan lists unpatchables
Database kingpin lists 32 products that can't be patched (yet) as GNU fixes second vuln
Who.is does the Harlem Shake
Blame it on LOLing XSS terroristas
Researchers tell black hats: 'YOU'RE SOOO PREDICTABLE'
Want to register that domain? We're way ahead of you.
Stunned by Shellshock Bash bug? Patch all you can – or be punished
UK data watchdog rolls up its sleeves, polishes truncheon
prev story

Whitepapers

A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.