Feeds

Conficker variant dispenses with need to phone home

Stealth variant Sidesteps MS-led takedown effort

Beginner's guide to SSL certificates

Virus authors have released a new variant of the infamous Conficker (Downadup) worm with enhanced auto-update features.

The changes in the new strain of the malware, dubbed Conficker B++, make it possible for malware authors to push out new code without publishing it on pre-programmed sites, as with earlier variants. The earlier approach has been frustrated by the recent formation of an alliance led by Microsoft geared up to block and take down sites associated with the worm.

"Perhaps as one response to the cabal's action, or simply to produce a more efficient push-based updating service, the Conficker authors have released a variant of Conficker B, which significantly upgrades their ability to flash Conficker drones with Win32 binaries from any address on the Internet," explains an analysis by security firm SRI International.

Conficker B++ is somewhat similar to Conficker B, with 294 of 297 sub-routines the same and 39 additional subroutines. The latest variant, first spotted on 16 February, is even more sneaky than its previous incarnations, SRI explains.

Conficker B++ is no longer limited to reinfection by similarly structured Conficker DLLs, but can now push new self-contained Win32 applications. These executables can infiltrate the host using methods that are not detected by the latest anti-Conficker security applications.

The malware also creates an additional backdoor on compromise machines to create an altogether trickier infectious agent, SRI explains.

In Conficker A and B, there appeared only one method to submit Win32 binaries to the digital signature validation path, and ultimately to the CreateProcess API call. This path required the use of the Internet rendezvous point to download the binary through an HTTP transaction.

Under Conficker B++, two new paths to binary validation and execution have been introduced to Conficker drones, both of which bypass the use of Internet Rendezvous points: an extension to the netapi32.dll patch and the new named pipe backdoor. These changes suggest a desire by the Conficker's authors to move away from a reliance on Internet rendezvous points to support binary update, and toward a more direct flash approach.

SRI reckons that Conficker-A has infected 4.7m machines, at one time or another, while Conficker-B has hit 6.7m IP addresses. These figures, as with previous estimates, come from an analysis of the number of machines that have ever tried to call into malware update sites. The actual number of infected hosts at any one time is lower than that. SRI estimates the botnet controlled by Conficker-A and Conficker-B is around 1m and 3m hosts, respectively, or a third of the raw estimate.

SRI's detailed analysis of Conficker, which includes flow charts illustrating the viral and detailed technical analysis, can be found here. ®

Intelligent flash storage arrays

More from The Register

next story
You really need to do some tech support for Aunty Agnes
Free anti-virus software, expires, stops updating and p0wns the world
Regin: The super-spyware the security industry has been silent about
NSA fingered as likely source of complex malware family
You stupid BRICK! PCs running Avast AV can't handle Windows fixes
Fix issued, fingers pointed, forums in flames
Privacy bods offer GOV SPY VICTIMS a FREE SPYWARE SNIFFER
Looks for gov malware that evades most antivirus
Patch NOW! Microsoft slings emergency bug fix at Windows admins
Vulnerability promotes lusers to domain overlords ... oops
HACKERS can DELETE SURVEILLANCE DVRS remotely – report
Hikvision devices wide open to hacking, claim securobods
prev story

Whitepapers

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.
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.
Designing and building an open ITOA architecture
Learn about a new IT data taxonomy defined by the four data sources of IT visibility: wire, machine, agent, and synthetic data sets.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
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.