Senin, 30 Maret 2009

CONFICKER MOVES TO THE NEXT LEVEL

Variant C represents the third major revision of the Conficker malware family, which first appeared on the Internet on 20 November 2008. C distinguishes itself as a significant revision to Conficker B. In fact, C leaves as little as 15% of the original B code base untouched. Whereas the recently reported B++ variant represented a more surgical derivative of B, C incorporates a major restructuring of B's previous thread architecture and program logic, including major functional additions such as a new peer-to-peer (P2P) coordination channel, and a revision of the domain generation algorithm (DGA). It is clear that the Conficker authors are well informed and are tracking efforts to eliminate the previous Conficker epidemics at the host and Internet governance level. In Conficker C, they have now responded with many of their own countermeasures to thwart these latest defenses.

For example, C's latest revision of Conficker's now well-known Internet rendezvous logic may represent a direct retort to the action of the Conficker Cabal, which recently blocked all domain registrations associated with the A and B strains. C now selects its rendezvous points from a pool of over 50,000 randomly generated domain name candidates each day. C further increases Conficker's top-level domain (TLD) spread from five TLDs in Conficker A, to eight TLDs in B, to 110 TLDs that must now be involved in coordination efforts to track and block C's potential DNS queries. With this latest escalation in domain space manipulation, C not only represents a significant challenge to those hoping to track its census, but highlights some weaknesses in the long-term viability of how Internet address and name space governance is conducted.

One interesting and minimally explored aspect of Conficker is its early and sophisticated adoption of binary encryption, digital signatures, and advanced hash algorithms to prevent third-party hijacking of the infected population. At its core, the main purpose of Conficker is to provide the authors with a secure binary updating service that effectively allows them instant control of millions of PCs worldwide. Through the use of these binary encryption methods, Conficker's authors have taken care to ensure that other groups cannot upload arbitrary binaries to their infected drone population, and these protections cover all Conficker updating services: Internet rendezvous point downloads, buffer overflow re-exploitation, and the latest P2P control protocol.

In evaluating this mechanism, we find that the Conficker authors have devised a sophisticated encryption protocol that is generally robust to direct attack. All three crypto-systems employed by Conficker's authors (RC4, RSA, and MD-6) also have one underlying commonality. They were all produced by Dr. Ron Rivest of MIT. Furthermore, the use of MD-6 is a particularly unusual algorithm selection, as it represents the latest encryption hash algorithm produced to date. The discovery of MD-6 in Conficker B is indeed highly unusual given Conficker's own development time line. We date the creation of Conficker A to have occurred in October 2008, roughly the same time frame that MD-6 had been publicly released by Dr. Rivest (see http://groups.csail.mit.edu/cis/md6). While A employed SHA-1, we can now confirm that MD-6 had been integrated into Conficker B by late December 2008 (i.e., the authors chose to incorporate a hash algorithm that had literally been made publicly available only a few weeks earlier).

Unfortunately for the Conficker authors, by mid-January, Dr. Rivest’s group submitted a revised version of the MD-6 algorithm, as a buffer overflow had been discovered in its implementation. This revision was inserted quietly, followed later by a more visible public announcement of the buffer overflow on 19 February 2009, with the release of the Fortify report (http://blog.fortify.com/repo/Fortify-SHA-3-Report.pdf). We confirmed that this buffer overflow was present in the Conficker B implementations. However, we also confirmed that this buffer overflow was not exploitable as a means to take control of Conficker hosts. Nevertheless, the Conficker developers were obviously aware of these developments, as they have now repaired their MD-6 implementation in Conficker C, using the identical fix made by Dr. Rivest's group. Clearly the authors are aware of, and adept at understanding and incorporating, the latest cryptographic advances, and are actively monitoring the latest developments in this community.

One major implication from the Conficker B and C variants, as well as other now recently emerging malware families, is the sophistication with which they are able to terminate, disable, reconfigure, or blackhole native operating system (OS) and third-party security services. We provide an in-depth analysis of Conficker's Security Product Disablement logic, to help illustrate the comprehensive challenge that modern malware poses to security products, and to Microsoft's anti-malware efforts. Conficker offers a nice illustration of the degree to which security vendors are being actively challenged to not just hunt for malicious logic, but to defend their own availability, integrity, and the network connectivity vital to providing them a continual flow of the latest malware threat intelligence.

Perhaps the most obvious frightening aspect of Conficker C is its clear potential to do harm. Among the long history of malware epidemics, very few can claim sustained worldwide infiltration of multiple millions of infected drones. Perhaps in the best case, Conficker may be used as a sustained and profitable platform for massive Internet fraud and theft. In the worst case, Conficker could be turned into a powerful offensive weapon for performing concerted information warfare attacks that could disrupt not just countries, but the Internet itself.

Finally, we must also acknowledge the multiple skill sets that are revealed within the evolving design and implementation of Conficker. Those responsible for this outbreak have demonstrated Internet-wide programming skills, advanced cryptographic skills, custom dual-layer code packing and code obfuscation skills, and in-depth knowledge of Windows internals and security products. They are among the first to introduce the Internet rendezvous point scheme, and have now integrated a sophisticated P2P protocol that does not require an embedded peer list. They have continually seeded the Internet with new MD5 variants, and have adapted their code base to address the latest attempts to thwart Conficker. They have infiltrated government sites, military networks, home PCs, critical infrastructure, small networks, and universities, around the world. Perhaps an even greater threat than what they have done so far, is what they have learned and what they will build next.

by:google surf

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