Difference between pages "Harlan Carvey" and "SuperFetch"

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[[File:HarlanCarvey.jpg|200px|thumb|right|Harlan Carvey]] [[Harlan Carvey]] is a computer forensics author, researcher and practitioner. He has written several books and tools focusing on [[Windows]] systems and [[Incident Response|incident response]]. His [http://windowsir.blogspot.com Windows Incident Response Blog] Harlan Carvey's interest in computer and information security began while he was an officer in the U.S. military, and a student at the Naval Postgraduate School, earning his MSEE. After leaving military service, he began working in the field of commercial and government information security consulting, performing vulnerability assessments and penetration tests. While employed at one company, he was the sole developer of a program for collecting security-specific information (i.e., Registry entries, file information, configuration settings, etc.) from Windows NT systems during vulnerability assessments. The purpose of the product was to overcome shortfalls in commercial scanning products and provide more valuable information to the customer. Harlan has also done considerable work in the area of incident response and forensics, performing internal and external investigations. He has also written a number of proof-of-concept tools for educating users in such topics as Windows null sessions, file signature analysis, and the retrieval of metadata from a variety of file formats. Harlan's experience with computers began in the early '80s, with a Timex-Sinclair 1000. Around that time, he was learning to program BASIC on an Apple IIe. From there, he moved on to computers such as the Epson QX-10 and the TRS-80, on which he programmed BASIC and learned some rudimentary PASCAL, using the TurboPASCAL compiler. Since then, he's worked with SunOS and Solaris systems, as well as various versions of DOS and Windows, OS/2, and Linux. Harlan has presented at a variety of computer security conferences, including Usenix, DefCon9, Black Hat, GMU2003/HTCIA/RCFG, WACCI, and PFIC2010. He has discussed various topics specific to issues on Windows platforms, such as data hiding, incident response, and forensic analysis. He has had articles published in the Information Security Bulletin, on the SecurityFocus web site, and in the Hakin9 magazine. Finally, Harlan has written a number of open source programs (including RegRipper), which have been made available online and via CDs/DVDs in his books. His [http://windowsir.blogspot.com/ Windows Incident Response] blog is updated on a regular basis.
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{{Expand}}
  
== Website ==
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SuperFetch is a performance enhancement introduced in [[Microsoft]] [[Windows|Windows Vista]] to reduce the time necessary to launch applications. SuperFetch works with the memory manager service in Windows to analyze memory usage patterns over time to determine the optimal memory content for a given user for a date or time of day. This differs from the [[Prefetch]] technique used in Microsoft Windows XP, which preloads data into memory without analyzing usage patterns.
  
* [http://windowsir.blogspot.com Harlan's Windows Incident Response Blog]
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From [http://msdn.microsoft.com/en-us/library/windows/hardware/dn653317(v=vs.85).aspx]: SuperFetch prioritizes the following kinds of pages to remain in memory:
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* Pages of applications that are used most frequently overall.
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* Pages of applications that are commonly used when resuming:
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** After extensive hibernation (for example, first thing in the morning).
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** After shorter periods of sleep or hibernation (for example, after lunch).
  
== Tools ==
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If SuperFetch detects that the system drive is a fast solid-state drive (SSD) (as measured by Windows Experience Index Disk score), then SuperFetch turns off [[ReadyBoot]].
  
* [http://code.google.com/p/winforensicaanalysis/downloads/list WinForensicAnalysis Tools] - Hosted on Google Code, includes files for the Windows Registry Forensics book.
 
  
== Books ==
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== Configuration ==
  
* ''[http://http://www.syngress.com/digital-forensics/Windows-Registry-Forensics/ Windows Registry Forensics]''
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Because SuperFetch appears to leave a system with no available memory, some users turn it off to create the appearance of having more free memory. The feature can be configured by changing the <tt>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters\EnableSuperfetch</tt> [[Registry]] key [http://www.codinghorror.com/blog/archives/000688.html]. A value of zero disables SuperFetch, one enables it for booting only, two for applications, and three for both applications and boot. This setting can also be changed using the Services console, <tt>services.msc</tt> [http://tiredblogger.wordpress.com/2007/03/27/superfetch-not-so-super-for-gaming/].
* ''[http://www.syngress.com/catalog/index.cfm?pid=4235 Windows Forensic Analysis]''
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* ''[http://www.amazon.com/Forensics-Incident-Addison-Wesley-Microsoft-Technology/dp/0321200985/ref=sr_1_3?ie=UTF8&s=books&qid=1200485877&sr=1-3 Windows Forensics and Incident Recovery]''
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== File Formats ==
* ''[http://www.amazon.com/Perl-Scripting-Security-Harlan-Carvey/dp/159749173X/ref=pd_bbs_sr_2?ie=UTF8&s=books&qid=1200485877&sr=1-2 Perl Scripting for Windows Security]''
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* ''A Study of Video Teleconferencing Traffic on a TCP/IP Network''
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Data for SuperFetch is gathered by the <tt>%SystemRoot%\System32\Sysmain.dll</tt>, part of the Service Host process, <tt>%SystemRoot%\System32\Svchost.exe</tt>, and stored in a series of files in the <tt>%SystemRoot%\Prefetch</tt> directory [http://www.microsoft.com/technet/technetmag/issues/2007/03/VistaKernel/]. These files appear to start with the prefix <tt>Ag</tt> and have a <tt>.db</tt> extension. The format of these files is not fully known, there is available unofficial partial specification [http://blog.rewolf.pl/blog/?p=214] and open source (GPL) dumper for .db files [http://code.google.com/p/rewolf-superfetch-dumper/]. Some information can be gleaned from these files by searching for [[Unicode]] [[strings]] in them.
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The SuperFetch feature is seeded with some basic usage patterns when the operating system is installed [http://channel9.msdn.com/showpost.aspx?postid=242429].
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== See Also ==
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* [[Prefetch]]
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* [[ReadyBoost]]
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* [[ReadyBoot]]
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* [[Windows SuperFetch Format|SuperFetch Format]]
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* [[Windows]]
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== External Links ==
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* [http://en.wikipedia.org/wiki/Windows_Vista_I/O_technologies#SuperFetch Wikipedia: Windows Vista I/O technologies - SuperFetch]
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* [http://channel9.msdn.com/showpost.aspx?postid=242429 Channel 9 Interview with Michael Fortin of Microsoft on SuperFetch]
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* [http://www.informationweek.com/news/showArticle.jhtml?articleID=196902178 Microsoft Predicts The Future With Vista's SuperFetch] from Information Week
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* [http://jessekornblum.com/presentations/dodcc08-2.pdf DC3 Presentation: My You Look SuperFetching], by Jesse Kornblum
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== Tools ==
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=== Open Source ===
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* [https://code.google.com/p/rewolf-superfetch-dumper/ rewolf-superfetch-dumper]
  
[[Category:People]]
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[[Category:Windows]]

Revision as of 01:48, 24 April 2014

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Further information might be found on the discussion page.

SuperFetch is a performance enhancement introduced in Microsoft Windows Vista to reduce the time necessary to launch applications. SuperFetch works with the memory manager service in Windows to analyze memory usage patterns over time to determine the optimal memory content for a given user for a date or time of day. This differs from the Prefetch technique used in Microsoft Windows XP, which preloads data into memory without analyzing usage patterns.

From [1]: SuperFetch prioritizes the following kinds of pages to remain in memory:

  • Pages of applications that are used most frequently overall.
  • Pages of applications that are commonly used when resuming:
    • After extensive hibernation (for example, first thing in the morning).
    • After shorter periods of sleep or hibernation (for example, after lunch).

If SuperFetch detects that the system drive is a fast solid-state drive (SSD) (as measured by Windows Experience Index Disk score), then SuperFetch turns off ReadyBoot.


Configuration

Because SuperFetch appears to leave a system with no available memory, some users turn it off to create the appearance of having more free memory. The feature can be configured by changing the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters\EnableSuperfetch Registry key [2]. A value of zero disables SuperFetch, one enables it for booting only, two for applications, and three for both applications and boot. This setting can also be changed using the Services console, services.msc [3].

File Formats

Data for SuperFetch is gathered by the %SystemRoot%\System32\Sysmain.dll, part of the Service Host process, %SystemRoot%\System32\Svchost.exe, and stored in a series of files in the %SystemRoot%\Prefetch directory [4]. These files appear to start with the prefix Ag and have a .db extension. The format of these files is not fully known, there is available unofficial partial specification [5] and open source (GPL) dumper for .db files [6]. Some information can be gleaned from these files by searching for Unicode strings in them.

The SuperFetch feature is seeded with some basic usage patterns when the operating system is installed [7].

See Also

External Links

Tools

Open Source