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20101018 資安新聞簡報. 報告者:曾家雄、劉旭哲、莊承恩. New Malware Murofet Following Conficker's Lead. October 15, 2010 Dennis Fisher. Conficker. A computer worm targeting the Microsoft Windows operating system Be detected in November 2008
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20101018 資安新聞簡報 報告者:曾家雄、劉旭哲、莊承恩
New Malware Murofet Following Conficker's Lead October 15, 2010 Dennis Fisher
Conficker • A computer worm targeting the Microsoft Windows operating system • Be detected in November 2008 • Co-opt machines and link them into a virtual computer that can be commanded remotely
Conficker Variant • Five variants of the Conficker worm are known and have been dubbed Conficker A, B, C, D and E
Payload Propagation • Variant A • Generates a list of 250 domain names every day across five TLDs • The domain names are generated from a pseudo-random number generator seeded with the current date
Payload Propagation • Variant B increases the number of TLDs to eight, and produce domain names disjoint from those of the variant A • Variant D generates daily a pool of 50000 domains across 110 TLDs, from which it randomly chooses 500 to attempt for that day • The generated domain names were also shortened from 8-11 to 4-9 characters to make them more difficult to detect with heuristics
Murofet • The main similarity between Conficker and Murofet is that both pieces of malware use a pre-determined algorithmto generate seemingly random domain • It generates pseudo-random domain names based on the year, month, day, and minute of execution • Upon executing, Murofet starts a thread that attempts to download malware updates
Pseudo-Random Domain Algorithm • It generates two DWORD values • The first is composed of the month, day, and low byte of the year of the date of execution, plus 0x30 (48) • The second DWORD value is based on the minute of execution, multiplied by 0x11 (17)
Pseudo-Random Domain Algorithm First Dword Day Month Year Second Dword + 0x30 Minute * 0x11 First Dword Second Dword 64 bits => 共16個nibles
Reference • http://community.websense.com/blogs/securitylabs/archive/2010/10/14/murofet-domain-generation-ala-conficker.aspx • http://threatpost.com/en_us/blogs/new-malware-murofet-following-confickers-lead-101510 • http://www.symantec.com/connect/blogs/w32downadupc-pseudo-random-domain-name-generation
Microsoft Wants to Cordon Off Botnet-Infected Computers 報告者:劉旭哲
Botnets = Zombie Network • DDoS • Spread spam • "collective action" to combat cyberthreats -- particularly botnets.
individual defense • firewalls, antivirus, and automatic updates • collective defense • Computer Emergency Response Teams (CERTs) • active defense • Offense
new users, devices, and application. • Zeus botnet that captured users' banking sign-on information. • New thinking and expanded approaches need to be applied to combat cyber threats
"If you were the person whose computer was infected, wouldn't you want to know?“ • Public Health Model • Computer = Human
Public Health Model • Two complementary approaches: • bolstering efforts to identify infected devices • promoting efforts to better demonstrate device health • Identify infected devices • Restrict infected devices • at least one access provider is now attempting this approach: Comcast
Comcast • Constant Guard • Damballa, a botnet research firm • Use toolbar • The first ISP to provide this type of in-browser notification
Demonstrate device health: • a mechanism to produce a health certificate • trust • access providers request health certificates and take appropriate action • create supporting policies and rules
Defect • If there are some emergency services, infected computers may still be permitted • For example, cell phone.
At least two advantages: • Before online banking activities • More effective remediation • ISP could know specific device
Conclusion • Not perfect • Balance security and privacy • Building a socially acceptable and financially sustainable model • Collective action
Reference • http://www.technewsworld.com/story/70998.html • http://go.microsoft.com/?linkid=9746317 • http://www.comcast.com/default.cspx • http://www.damballa.com/ • http://news.cnet.com/8301-27080_3-20018168-245.html#ixzz1133KPVK8
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