Difference between pages "Category:Digital Forensics XML" and "Google Chrome"

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''Digital Forensics XML'' (DFXML) is the effort to create an XML schema to allow for easy interoperability between different forensic tools.  
+
Google Chrome is a [[Web Browser|web browser]] developed by Google Inc.
  
Currently there is no Digital Forensics XML standard and there is no fixed schema. Instead, we are slowly creating a set of tools that can produce or ingest XML with a common set of tags. It would be nice to have a more aggressive effort, but to date there has not been sufficient funding.
+
== Configuration ==
 +
The Google Chrome configuration can be found in the '''Preferences''' file.
  
Given this state of affairs, our current strategy is to:
+
On Linux
 +
<pre>
 +
/home/$USER/.config/google-chrome/Default/Preferences
 +
</pre>
  
* Develop a set of standardized tags and data representations for current XML tools.
+
On MacOS-X
* Modify our tools to produce XML similar to the sample XML.
+
<pre>
* Develop a DTD and schema to allow XML validation.
+
/Users/$USER/Library/Application Support/Google/Chrome/Default/Preferences
 +
</pre>
  
==Tools==
+
On Windows XP
 +
<pre>
 +
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Preferences
 +
</pre>
  
===Tools that produce DFXML===
+
On Windows Vista and later
The following tools are known to produce DFXML:
+
<pre>
* The [[fiwalk]] C++ program produces DFXML for files from disk images using SleuthKit.
+
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Preferences
* The following carvers use (or will soon use) DFXML for their report files to indicate the sectors from which carved objects are found:
+
</pre>
** [[frag_find]] (hash-based carver)
+
** [[photorec]]
+
** scalpel
+
* [[bulk_extractor]] uses DFXML to report the configuration of each run and the provenance of the input files.
+
* [[afxml]], part of AFFLIB, converts metadata for disk images into DFXML format.
+
* [[ewfinfo]], part of libewf, can output metadata for EWF disk images in DFXML format.
+
* [[md5deep]], [[sha1deep]], [[hashdeep]], and the other programs in the md5deep package will produce DFXML hash files in the new Version 4 of the program (currently under development).
+
  
===Tools that consume DFXML===
+
Or for '''Chromium'''
* [[frag_find]], the hash-based carver, will be able to read piecewise hash files in DFXML format.
+
* iblkfind.py, part of the [[fiwalk]] distribution, will report the file associated with any disk sector.
+
* identify_filenames.py, part of the [[bulk_extractor]] distribution, will take a bulk_extractor feature file and annotate it with the names of the files from which each feature was extracted.
+
* idifference.py, part of the [[fiwalk]] distribution, will report the difference between two disk images.
+
* imap.py, part of the [[fiwalk]] distribution, will draw a map of what's on a disk. Only useful for small partitions.
+
* imicrosoft_redact.py, part of the [[fiwalk]] distribution, will break the Microsoft binaries in a disk image.
+
* iverify.py, part of the [[fiwalk]] distribution, will verify that the contents of files in a DFXML file haven't been changed.
+
  
===Tools that transform DFXML===
+
On Linux
* sanitize_xml.py, part of the fiwalk distribution, will remove personally-identifiable information in filenames and directory names from a DFXML file.
+
<pre>
 +
/home/$USER/.config/chromium/Default/Preferences
 +
</pre>
  
 +
On MacOS-X
 +
<pre>
 +
/Users/$USER/Library/Application Support/Chromium/Default/Preferences
 +
</pre>
  
===DFXML Toolkits===
+
On Windows XP
The following toolkits are useful for building new tools that read and write DFXML:
+
<pre>
* The dfxml.py Python module implements objects for reading and writing DFXML.
+
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Preferences
* The xml.cpp and xml.h files that are included in the bulk_extractor and md5deep (version 4) source code are a good C++ implementation for DFXML generation.
+
</pre>
* The xml.c and xml.h files that are included in the photorec (new version) source code are a good C implementation for DFXML generation.
+
  
===XML Forensics Tools and Toolkits===
+
On Windows Vista and later
* We are creating a DFXML strategy for distributing hash sets.
+
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Preferences
 +
</pre>
  
==DFXML Bibliography==
+
=== Plugins ===
===Papers===
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#Garfinkel, S. [http://simson.net/clips/academic/2012.DI.dfxml.pdf Digital Forensics XML and the DFXML toolset], Digital Investigation, 2012.
+
#Garfinkel, Simson., [http://simson.net/clips/academic/2009.SADFE.xml_forensics.pdf Automating Disk Forensic Processing with SleuthKit, XML and Python], Systematic Approaches to Digital Forensics Engineering (IEEE/SADFE 2009), Oakland, California. (Acceptance rate: 32%, 7/22)
+
===Presentations===
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# [http://simson.net/ref/2011/2011-12-07%20DFXML.pdf DFXML, Simson Garfinkel, December 7, 2011]
+
  
==See Also==
+
Information about plugins can be found under the "plugins section" of the Preferences file.
* [[fiwalk]]
+
 
* [http://www.cgsecurity.org/wiki/Data_Carving_Log XML Log Sample for photorec]
+
=== DNS Prefetching ===
* [http://mark0.net/soft-tridscan-e.html TrIDScan], which has an XML language to describe file types.
+
 
[[Category:Top-Level]]
+
DNS is prefetched for related sites, e.g. links on the page.
 +
This behavior is controlled by the setting "Predict network actions to improve page load performance", which is enabled by default.
 +
 
 +
If enabled the Preferences file contains:
 +
<pre>
 +
  "dns_prefetching": {
 +
      "enabled": true,
 +
</pre>
 +
 
 +
If disabled the Preferences file contains:
 +
<pre>
 +
  "dns_prefetching": {
 +
      "enabled": false,
 +
</pre>
 +
 
 +
== Start-up DNS queries ==
 +
 
 +
When Chrome starts it queries for several non-existing hostnames that consists of a 10 random characters, E.g.
 +
<pre>
 +
ttrgoiknff.mydomain.com
 +
bxjhgftsyu.mydomain.com
 +
yokjbjiagd.mydomain.com
 +
</pre>
 +
 
 +
This is used to determine if your ISP is hijacking NXDOMAIN results [http://www.google.com/support/forum/p/Chrome/thread?tid=3511015c72a7b314&hl=en].
 +
 
 +
== Disk Cache ==
 +
Google Chrome uses multiple caches, from [http://src.chromium.org/viewvc/chrome/trunk/src/net/base/cache_type.h?view=markup]:
 +
<pre>
 +
// The types of caches that can be created.
 +
enum CacheType {
 +
    DISK_CACHE,  // Disk is used as the backing storage.
 +
    MEMORY_CACHE,  // Data is stored only in memory.
 +
    MEDIA_CACHE,  // Optimized to handle media files.
 +
    APP_CACHE,  // Backing store for an AppCache.
 +
    SHADER_CACHE, // Backing store for the GL shader cache.
 +
    PNACL_CACHE, // Backing store the PNaCl translation cache
 +
};
 +
</pre>
 +
 
 +
The Google Chrome disk cache can be found in:
 +
 
 +
On Linux
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/Default/Cache/
 +
/home/$USER/.cache/google-chrome/Default/Cache/
 +
/home/$USER/.config/chromium/Default/Cache/
 +
/home/$USER/.config/google-chrome/Default/Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/Default/Media Cache/
 +
/home/$USER/.cache/google-chrome/Default/Media Cache/
 +
/home/$USER/.config/chromium/Default/Media Cache/
 +
/home/$USER/.config/google-chrome/Default/Media Cache/
 +
</pre>
 +
 
 +
 
 +
<pre>
 +
/home/$USER/.config/chromium/Default/Application Cache/Cache/
 +
/home/$USER/.config/google-chrome/Default/Application Cache/Cache/
 +
</pre>
 +
 
 +
 
 +
<pre>
 +
/home/$USER/.config/chromium/Default/GPUCache/
 +
/home/$USER/.config/google-chrome/Default/GPUCache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/PnaclTranslationCache/
 +
/home/$USER/.cache/google-chrome/PnaclTranslationCache/
 +
</pre>
 +
 
 +
On MacOS-X
 +
<pre>
 +
/Users/$USER/Caches/Chromium/Default/Cache/
 +
/Users/$USER/Caches/Google/Chrome/Default/Cache/
 +
</pre>
 +
 
 +
On Windows XP
 +
<pre>
 +
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Cache\
 +
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Cache\
 +
</pre>
 +
 
 +
On Windows Vista and later
 +
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\Default\Cache\
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Cache\
 +
</pre>
 +
 
 +
The Chrome Cache contains different files with the following file names:
 +
* index
 +
* data_#; where # contains a decimal digit.
 +
* f_######; where # contains a hexadecimal digit.
 +
 
 +
For more info see Chrome developers site [http://www.chromium.org/developers/design-documents/network-stack/disk-cache].
 +
 
 +
== History ==
 +
Chrome stores the history of visited sites in a file named '''History'''. This file uses the [[SQLite database format]].
 +
 
 +
The '''History''' file can be found in same location as the '''Preferences''' file.
 +
 
 +
There is also '''Archived History''' that predates information in the '''History''' file.
 +
Note that the '''Archived History''' only contains visits.
 +
 
 +
=== Timestamps ===
 +
The '''History''' file uses the different timestamps.
 +
 
 +
==== visits.visit_time ====
 +
 
 +
The '''visits.visit_time''' is in (the number of) microseconds since January 1, 1601 UTC
 +
 
 +
Some Python code to do the conversion into human readable format:
 +
<pre>
 +
date_string = datetime.datetime( 1601, 1, 1 )
 +
            + datetime.timedelta( microseconds=timestamp )
 +
</pre>
 +
 
 +
Note that this timestamp is not the same as a Windows filetime which is (the number of) 100 nanoseconds since January 1, 1601 UTC
 +
 
 +
==== downloads.start_time ====
 +
 
 +
The '''downloads.start_time''' is in (the number of) seconds since January 1, 1970 UTC
 +
 
 +
Some Python code to do the conversion into human readable format:
 +
<pre>
 +
date_string = datetime.datetime( 1970, 1, 1 )
 +
            + datetime.timedelta( seconds=timestamp )
 +
</pre>
 +
 
 +
=== Example queries ===
 +
Some example queries:
 +
 
 +
To get an overview of the visited sites:
 +
<pre>
 +
SELECT datetime(((visits.visit_time/1000000)-11644473600), "unixepoch"), urls.url, urls.title FROM urls, visits WHERE urls.id = visits.url;
 +
</pre>
 +
 
 +
Note that the visit_time conversion looses precision.
 +
 
 +
To get an overview of the downloaded files:
 +
<pre>
 +
SELECT datetime(downloads.start_time, "unixepoch"), downloads.url, downloads.full_path, downloads.received_bytes, downloads.total_bytes FROM downloads;
 +
</pre>
 +
 
 +
How the information of the downloaded files is stored in the database can vary per version of Chrome as of version 26:
 +
<pre>
 +
SELECT datetime(((downloads.start_time/1000000)-11644473600), "unixepoch"), downloads.target_path, downloads_url_chains.url, downloads.received_bytes, downloads.total_bytes \
 +
FROM downloads, downloads_url_chains WHERE downloads.id = downloads_url_chains.id;
 +
</pre>
 +
 
 +
== See Also ==
 +
 
 +
* [[SQLite database format]]
 +
 
 +
== External Links ==
 +
* [http://en.wikipedia.org/wiki/Google_Chrome Wikipedia article on Google Chrome]
 +
* [http://www.chromium.org/user-experience/user-data-directory The Chromium Projects - User Data Directory]
 +
* [http://www.chromium.org/developers/design-documents/network-stack/disk-cache Chrome Disk Cache]
 +
* [http://www.google.com/support/forum/p/Chrome/thread?tid=3511015c72a7b314&hl=en Chrome support forum article random 10 character hostnames on startup]
 +
* [http://www.useragentstring.com/pages/Chrome/ Chrome User Agent strings]
 +
* [http://computer-forensics.sans.org/blog/2010/01/21/google-chrome-forensics/ Google Chrome Forensics] by [[Kristinn Guðjónsson]], January 21, 2010
 +
* [http://linuxsleuthing.blogspot.ch/2013/02/cashing-in-on-google-chrome-cache.html?m=1 Cashing in on the Google Chrome Cache], [[John Lehr]], February 24, 2013
 +
* [http://www.obsidianforensics.com/blog/history-index-files-removed-from-chrome/ History Index files removed from Chrome v30], by Ryan Benson, October 2, 2013
 +
* [https://hindsight-internet-history.googlecode.com/files/Evolution_of_Chrome_Databases.png Evolution of Chrome Databases], by Ryan Benson, November 12, 2013
 +
 
 +
== Tools ==
 +
=== Open Source ===
 +
* [https://code.google.com/p/hindsight-internet-history/ hindsight-internet-history]
 +
 
 +
[[Category:Applications]]
 +
[[Category:Web Browsers]]

Revision as of 04:50, 30 April 2014

Google Chrome is a web browser developed by Google Inc.

Configuration

The Google Chrome configuration can be found in the Preferences file.

On Linux

/home/$USER/.config/google-chrome/Default/Preferences

On MacOS-X

/Users/$USER/Library/Application Support/Google/Chrome/Default/Preferences

On Windows XP

C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Preferences

On Windows Vista and later

C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Preferences

Or for Chromium

On Linux

/home/$USER/.config/chromium/Default/Preferences

On MacOS-X

/Users/$USER/Library/Application Support/Chromium/Default/Preferences

On Windows XP

C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Preferences

On Windows Vista and later

C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Preferences

Plugins

Information about plugins can be found under the "plugins section" of the Preferences file.

DNS Prefetching

DNS is prefetched for related sites, e.g. links on the page. This behavior is controlled by the setting "Predict network actions to improve page load performance", which is enabled by default.

If enabled the Preferences file contains:

   "dns_prefetching": {
      "enabled": true,

If disabled the Preferences file contains:

   "dns_prefetching": {
      "enabled": false,

Start-up DNS queries

When Chrome starts it queries for several non-existing hostnames that consists of a 10 random characters, E.g.

ttrgoiknff.mydomain.com
bxjhgftsyu.mydomain.com
yokjbjiagd.mydomain.com

This is used to determine if your ISP is hijacking NXDOMAIN results [1].

Disk Cache

Google Chrome uses multiple caches, from [2]:

// The types of caches that can be created.
enum CacheType {
    DISK_CACHE,  // Disk is used as the backing storage.
    MEMORY_CACHE,  // Data is stored only in memory.
    MEDIA_CACHE,  // Optimized to handle media files.
    APP_CACHE,  // Backing store for an AppCache.
    SHADER_CACHE, // Backing store for the GL shader cache.
    PNACL_CACHE, // Backing store the PNaCl translation cache
};

The Google Chrome disk cache can be found in:

On Linux

/home/$USER/.cache/chromium/Default/Cache/
/home/$USER/.cache/google-chrome/Default/Cache/
/home/$USER/.config/chromium/Default/Cache/
/home/$USER/.config/google-chrome/Default/Cache/
/home/$USER/.cache/chromium/Default/Media Cache/
/home/$USER/.cache/google-chrome/Default/Media Cache/
/home/$USER/.config/chromium/Default/Media Cache/
/home/$USER/.config/google-chrome/Default/Media Cache/


/home/$USER/.config/chromium/Default/Application Cache/Cache/
/home/$USER/.config/google-chrome/Default/Application Cache/Cache/


/home/$USER/.config/chromium/Default/GPUCache/
/home/$USER/.config/google-chrome/Default/GPUCache/
/home/$USER/.cache/chromium/PnaclTranslationCache/
/home/$USER/.cache/google-chrome/PnaclTranslationCache/

On MacOS-X

/Users/$USER/Caches/Chromium/Default/Cache/
/Users/$USER/Caches/Google/Chrome/Default/Cache/

On Windows XP

C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Cache\
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Cache\

On Windows Vista and later

C:\Users\%USERNAME%\AppData\Local\Google\Chromium\Default\Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Cache\

The Chrome Cache contains different files with the following file names:

  • index
  • data_#; where # contains a decimal digit.
  • f_######; where # contains a hexadecimal digit.

For more info see Chrome developers site [3].

History

Chrome stores the history of visited sites in a file named History. This file uses the SQLite database format.

The History file can be found in same location as the Preferences file.

There is also Archived History that predates information in the History file. Note that the Archived History only contains visits.

Timestamps

The History file uses the different timestamps.

visits.visit_time

The visits.visit_time is in (the number of) microseconds since January 1, 1601 UTC

Some Python code to do the conversion into human readable format:

date_string = datetime.datetime( 1601, 1, 1 )
            + datetime.timedelta( microseconds=timestamp )

Note that this timestamp is not the same as a Windows filetime which is (the number of) 100 nanoseconds since January 1, 1601 UTC

downloads.start_time

The downloads.start_time is in (the number of) seconds since January 1, 1970 UTC

Some Python code to do the conversion into human readable format:

date_string = datetime.datetime( 1970, 1, 1 )
            + datetime.timedelta( seconds=timestamp )

Example queries

Some example queries:

To get an overview of the visited sites:

SELECT datetime(((visits.visit_time/1000000)-11644473600), "unixepoch"), urls.url, urls.title FROM urls, visits WHERE urls.id = visits.url;

Note that the visit_time conversion looses precision.

To get an overview of the downloaded files:

SELECT datetime(downloads.start_time, "unixepoch"), downloads.url, downloads.full_path, downloads.received_bytes, downloads.total_bytes FROM downloads;

How the information of the downloaded files is stored in the database can vary per version of Chrome as of version 26:

SELECT datetime(((downloads.start_time/1000000)-11644473600), "unixepoch"), downloads.target_path, downloads_url_chains.url, downloads.received_bytes, downloads.total_bytes \
FROM downloads, downloads_url_chains WHERE downloads.id = downloads_url_chains.id;

See Also

External Links

Tools

Open Source