Difference between pages "MAC times" and "Google Chrome"

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The term '''MAC times''' refers to the timestamps of the latest ''modification'' (mtime) or last written time, ''access'' (atime) or ''change'' (ctime) of a certain file.
+
Google Chrome is a [[Web Browser|web browser]] developed by Google Inc.
  
[[Unix]] systems maintain the historical interpretation of ''ctime'' as the time when certain file metadata, not its contents, were last changed, such as the file's permissions or owner (e.g. 'This files metadata was changed on 05/05/02 12:15pm').
+
== Configuration ==
 +
The Google Chrome configuration can be found in the '''Preferences''' file.
  
[[Windows]] systems are the only systems that use ''birth'' (btime) or creation (crtime) time (e.g. 'This file was created on 05/05/02 12:15pm'). Hence MACB; Modification, Access, Change and Birth.
+
On Linux
 +
<pre>
 +
/home/$USER/.config/google-chrome/Default/Preferences
 +
</pre>
  
In [[NTFS]] each file has a time stamp for 'Create', 'Modify', 'Access', and 'Entry Modified'. The latter refers to the time when the MFT entry itself was modified. These four values are commonly abbreviated as the 'MACE' values.
+
On MacOS-X
 +
<pre>
 +
/Users/$USER/Library/Application Support/Google/Chrome/Default/Preferences
 +
</pre>
  
Other file systems like [[HFS+|HFS]] include different timestamps like e.g. a backup time.
+
On Windows XP
 +
<pre>
 +
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Preferences
 +
</pre>
  
== Time resolution ==
+
On Windows Vista and later
When dealing with MAC times it's important to know and understand the concept of time resolution.
+
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Preferences
 +
</pre>
  
On [[FAT]] file system (in Windows NT):
+
Or for '''Chrome SxS''' (Chrome side-by-side)
* the creation time has a resolution of 10 milliseconds,
+
* the last written time has a resolution of 2 seconds,
+
* and the access time has a resolution of 1 day.
+
  
On NTFS, access time has a resolution of 1 hour [http://msdn.microsoft.com/en-us/library/ms724284.aspx].
+
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome SxS\User Data\Default\Preferences
 +
</pre>
  
== Access Time Update ==
+
Or for '''Chromium'''
On various operating systems the update of the access time can be disabled. This means when a file is accessed the atime in the corresponding file system entry is not updated.
+
  
=== [[Windows]] ===
+
On Linux
 +
<pre>
 +
/home/$USER/.config/chromium/Default/Preferences
 +
</pre>
  
In Windows the access time behavior is controlled by the registry key:
+
On MacOS-X
 
<pre>
 
<pre>
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\NtfsDisableLastAccessUpdate
+
/Users/$USER/Library/Application Support/Chromium/Default/Preferences
 
</pre>
 
</pre>
  
Where a value of ''1'' indicates the access time update being disabled.
+
On Windows XP
 +
<pre>
 +
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Preferences
 +
</pre>
  
This is the default setting as for [[Windows]] Vista.
+
On Windows Vista and later
 +
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Preferences
 +
</pre>
  
=== [[Linux]] ===
+
=== Plugins ===
  
In Linux the ''noatime'' mount option indicates the access time update should be disabled.
+
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:
 +
<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>
 +
 
 +
<b>Note that $PROFILE (or %PROFILE%) the paths below is the profile dependent subdirectory which is normally Default but also could be Profile1, Profile2, etc.</b>
 +
 
 +
The Google Chrome disk cache can be found in:
 +
 
 +
On Linux
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/$PROFILE/Cache/
 +
/home/$USER/.cache/google-chrome/$PROFILE/Cache/
 +
/home/$USER/.config/chromium/$PROFILE/Cache/
 +
/home/$USER/.config/google-chrome/$PROFILE/Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/$PROFILE/Media Cache/
 +
/home/$USER/.cache/google-chrome/$PROFILE/Media Cache/
 +
/home/$USER/.config/chromium/$PROFILE/Media Cache/
 +
/home/$USER/.config/google-chrome/$PROFILE/Media Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.config/chromium/$PROFILE/Application Cache/Cache/
 +
/home/$USER/.config/google-chrome/$PROFILE/Application Cache/Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.config/chromium/$PROFILE/GPUCache/
 +
/home/$USER/.config/google-chrome/$PROFILE/GPUCache/
 +
</pre>
 +
 
 +
<pre>
 +
/home/$USER/.cache/chromium/PnaclTranslationCache/
 +
/home/$USER/.cache/google-chrome/PnaclTranslationCache/
 +
</pre>
 +
 
 +
On MacOS-X
 +
<pre>
 +
/Users/$USER/Library/Caches/Chromium/$PROFILE/Cache
 +
/Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Cache
 +
</pre>
 +
 
 +
<b>TODO confirm the following paths</b>
 +
<pre>
 +
/Users/$USER/Caches/Chromium/$PROFILE/Cache/
 +
/Users/$USER/Caches/Google/Chrome/$PROFILE/Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/Users/$USER/Library/Caches/Chromium/$PROFILE/Media Cache
 +
/Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Media Cache
 +
</pre>
 +
 
 +
<pre>
 +
/Users/$USER/Library/Application Support/Chromium/$PROFILE/Application Cache/Cache/
 +
/Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/Application Cache/Cache/
 +
</pre>
 +
 
 +
<pre>
 +
/Users/$USER/Library/Application Support/Chromium/$PROFILE/GPUCache/
 +
/Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/GPUCache/
 +
</pre>
 +
 
 +
<pre>
 +
/Users/$USER/Library/Caches/Chromium/PnaclTranslationCache/
 +
/Users/$USER/Library/Caches/Google/Chrome/PnaclTranslationCache/
 +
</pre>
 +
 
 +
On Windows XP
 +
 
 +
<b>TODO confirm the following paths</b>
 +
<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\%PROFILE%\Cache\
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Cache\
 +
</pre>
 +
 
 +
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Application Cache\Cache\
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Application Cache\Cache\
 +
</pre>
 +
 
 +
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Media Cache\
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Media Cache\
 +
</pre>
 +
 
 +
<pre>
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\GPUCache\
 +
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\GPUCache\
 +
</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 Disk Cache Format]].
 +
 
 +
== 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>
 +
 
 +
== Cookies ==
 +
Chrome stores the cookies in a file named '''Cookies'''. This file uses the [[SQLite database format]].
 +
 
 +
=== Extension Cookies ===
 +
Chrome stores the cookies used by extensions in a file named '''Extension Cookies'''. This file uses the [[SQLite database format]].
 +
 
 +
<pre>
 +
SELECT datetime(((cookies.creation_utc/1000000)-11644473600), "unixepoch"), cookies.host_key, cookies.name, cookies.value, cookies.path, \
 +
datetime(((cookies.expires_utc/1000000)-11644473600), "unixepoch"), cookies.secure, cookies.httponly, datetime(((cookies.last_access_utc/1000000)-11644473600), "unixepoch"), \
 +
cookies.has_expires, cookies.persistent, cookies.priority FROM cookies;
 +
</pre>
  
 
== See Also ==
 
== See Also ==
  
* [[Timestomp]]
+
* [[SQLite database format]]
  
 
== External Links ==
 
== 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
  
* [http://en.wikipedia.org/wiki/MAC_times Wikipedia: MAC times]
+
== Tools ==
* [http://www.drdobbs.com/what-are-mactimes/184404275 What Are MACtimes?], by Dan Farmer, Oct 2000
+
=== Open Source ===
 +
* [https://code.google.com/p/hindsight-internet-history/ hindsight-internet-history]
  
=== NTFS ===
+
[[Category:Applications]]
* [http://www.winguides.com/registry/display.php/50/ Disable the NTFS Last Access Time Stamp]
+
[[Category:Web Browsers]]
* [http://support.microsoft.com/kb/299648 Microsoft KB 299648: Description of NTFS date and time stamps for files and folders]
+

Revision as of 03:42, 22 June 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 Chrome SxS (Chrome side-by-side)

C:\Users\%USERNAME%\AppData\Local\Google\Chrome SxS\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
};

Note that $PROFILE (or %PROFILE%) the paths below is the profile dependent subdirectory which is normally Default but also could be Profile1, Profile2, etc.

The Google Chrome disk cache can be found in:

On Linux

/home/$USER/.cache/chromium/$PROFILE/Cache/
/home/$USER/.cache/google-chrome/$PROFILE/Cache/
/home/$USER/.config/chromium/$PROFILE/Cache/
/home/$USER/.config/google-chrome/$PROFILE/Cache/
/home/$USER/.cache/chromium/$PROFILE/Media Cache/
/home/$USER/.cache/google-chrome/$PROFILE/Media Cache/
/home/$USER/.config/chromium/$PROFILE/Media Cache/
/home/$USER/.config/google-chrome/$PROFILE/Media Cache/
/home/$USER/.config/chromium/$PROFILE/Application Cache/Cache/
/home/$USER/.config/google-chrome/$PROFILE/Application Cache/Cache/
/home/$USER/.config/chromium/$PROFILE/GPUCache/
/home/$USER/.config/google-chrome/$PROFILE/GPUCache/
/home/$USER/.cache/chromium/PnaclTranslationCache/
/home/$USER/.cache/google-chrome/PnaclTranslationCache/

On MacOS-X

/Users/$USER/Library/Caches/Chromium/$PROFILE/Cache
/Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Cache

TODO confirm the following paths

/Users/$USER/Caches/Chromium/$PROFILE/Cache/
/Users/$USER/Caches/Google/Chrome/$PROFILE/Cache/
/Users/$USER/Library/Caches/Chromium/$PROFILE/Media Cache
/Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Media Cache
/Users/$USER/Library/Application Support/Chromium/$PROFILE/Application Cache/Cache/
/Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/Application Cache/Cache/
/Users/$USER/Library/Application Support/Chromium/$PROFILE/GPUCache/
/Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/GPUCache/
/Users/$USER/Library/Caches/Chromium/PnaclTranslationCache/
/Users/$USER/Library/Caches/Google/Chrome/PnaclTranslationCache/

On Windows XP

TODO confirm the following paths

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\%PROFILE%\Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Application Cache\Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Application Cache\Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Media Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Media Cache\
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\GPUCache\
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\GPUCache\

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 Disk Cache Format.

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;

Cookies

Chrome stores the cookies in a file named Cookies. This file uses the SQLite database format.

Extension Cookies

Chrome stores the cookies used by extensions in a file named Extension Cookies. This file uses the SQLite database format.

SELECT datetime(((cookies.creation_utc/1000000)-11644473600), "unixepoch"), cookies.host_key, cookies.name, cookies.value, cookies.path, \
datetime(((cookies.expires_utc/1000000)-11644473600), "unixepoch"), cookies.secure, cookies.httponly, datetime(((cookies.last_access_utc/1000000)-11644473600), "unixepoch"), \
cookies.has_expires, cookies.persistent, cookies.priority FROM cookies;

See Also

External Links

Tools

Open Source