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A Python script to parse the NTFS USN journal

Project description

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USN-Journal-Parser

Python script to parse the NTFS USN Change Journal

Description

The NTFS USN Change journal is a volume-specific file which logs metadata changes to files. It is a treasure trove of information during a forensic investigation. The change journal is located at $Extend\$UsnJrnl:$J.

usn.py is a script written in Python which parses the journal’s contents, and features a myriad of output formats.

Default Output

With no command-line options set, usn.py will produce USN journal records in the format below:

dev@computer:$ python usn.py -f usnjournal
2016-01-26 18:56:20.046268 | test.vbs | ARCHIVE  | DATA_OVERWRITE DATA_EXTEND

Command-Line Options

optional arguments:
  -h, --help            show this help message and exit
  -b, --body            Return USN records in comma-separated format
  -c, --csv             Return USN records in comma-separated format
  -f FILE, --file FILE  Parse the given USN journal file
  -q, --quick           Parse a large journal file quickly
  -s SYSTEM, --system SYSTEM
                    System name (use with -t)
  -t, --tln             TLN output (use with -s)
  -v, --verbose         Return all USN properties for each record (JSON)

–quick

Warning: This logic does make (very good) assumptions about the data in question. On the off chance you are experience issues using this functionality just switch back to using usn.py without the –quick flag. Personally, I have never had issues with it.

The USN Journal is a Sparse File. Depending on how the file was extracted, it may be bloated with gigabytes of NULL bytes. As such, a parser needs to read through these NULL bytes to find the first valid USN record before it can begin producing results.

Leveraging an interpreted language such as Perl or Python can be a time consuming process if the journal file is large. Using this script, apply the –quick / -q flag to perform this search more quickly: by jumping ahead a gigabyte at a time seeking for valid USN data. Obviously, seeking ahead one gigabyte at a time requires the journal in question to be at least one gigabyte in size. If it isn’t, the script will simply produce an error and exit:

dev@computer$ python usn.py -f usnjournal --quick
[ - ] This USN journal is not large enough for the --quick functionality
[ - ] Exitting...

Below is an example of the time it takes to find valid data in a large USN journal - 39GB in size, containing mostly NULL bytes. This example is not using the –quick functionality and takes over six minutes to begin producing results:

PS Dev:\Desktop> Measure-Command {C:\Python27\python.exe usn.py -f usnjournal}
Hours             : 0
Minutes           : 6
Seconds           : 3
Milliseconds      : 766
Ticks             : 3637662181
TotalDays         : 0.00421025715393519
TotalHours        : 0.101046171694444
TotalMinutes      : 6.06277030166667
TotalSeconds      : 363.7662181
TotalMilliseconds : 363766.2181

Now the same USN journal file, but with the –quick flag invoked. The time it takes to find data is cut down to just under three seconds:

PS Dev:\Desktop> Measure-Command {C:\Python27\python.exe usn.py -f usnjournal --quick}
Hours             : 0
Minutes           : 0
Seconds           : 2
Milliseconds      : 822
Ticks             : 28224455
TotalDays         : 3.2667193287037E-05
TotalHours        : 0.000784012638888889
TotalMinutes      : 0.0470407583333333
TotalSeconds      : 2.8224455
TotalMilliseconds : 2822.4455

–csv

Using the CSV flag will, as expected, provide results in CSV format. Using the –csv / -c option provides the same USN fields as default output:

  • Timestamp
  • Filename
  • File attributes
  • Reason

An example of what this looks like is below:

dev@computer:~$python usn.py -f usnjournal --csv
timestamp,filename,fileattr,reason
2015-10-09 21:37:58.836242,A75BFDE52F3DD8E6.dat,ARCHIVE NOT_CONTENT_INDEXED,DATA_EXTEND FILE_CREATE

–verbose

Return all USN record members for each record with the –verbose / -v flag. The results are JSON-formatted.

dev@computer:~$python usn.py -f usnjournal --verbose
{
    "recordlen": 96,
    "majversion": 2,
    "minversion": 0,
    "mftSequenceNumber": 1,
    "mftEntryNumber": 95075,
    "parentMftSequenceNumber": 1,
    "parentMftEntryNumber": 2221,
    "usn": 432,
    "timestamp": "2016-02-22 02:59:26.374840",
    "reason": "FILE_DELETE CLOSE ",
    "sourceinfo": 0,
    "sid": 0,
    "fileattr": "ARCHIVE ",
    "filenamelen": 34,
    "filenameoffset": 60,
    "filename": "WindowsUpdate.log"
}

–grep / -g

dev@computer:~$ python usn.py -f usnjournal --grep test.txt

2016-04-11 00:26:09.324654 | test.txt | ARCHIVE  | FILE_CREATE
2016-04-11 00:26:09.324654 | test.txt | ARCHIVE  | FILE_CREATE CLOSE
2016-04-11 00:26:09.324654 | test.txt | ARCHIVE  | FILE_DELETE CLOSE

Installation

Using setup.py:

python setup.py install

Using pip:

pip install usnparser

Project details


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