Cartes-fiches

Cartes-fiches 8 Cartes-fiches
Utilisateurs 1 Utilisateurs
Langue English
Niveau Université
Crée / Actualisé 20.06.2019 / 01.07.2020
Attribution de licence Non précisé
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When searching what do you search for?

Searching for what?

  • something you know
  • something you don't know
  • search file names
  • search file content
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What are the chalanges when performing a search?

Challenges:

  • too many hits
  • hidden content (steganography) is not found
  • protectet content (steganography) is not found
  • compund files (zip, tar, attachments, embedded) are harder to serach - need to extracted first
  • proprietary file formats - hard to search because unknown of how to search
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What sleuthkit command can be used to search ?

fls 

fls outputs a large file list, deleted file, multiple partitions/drives/PCs

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What two GNU commands can be used for searching?

GNU grep

GNU find

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What UNIX command can you use to extract strings from images?

UNIX Strings

  • strings -td image.dd
  • strings -td -e l image.dd
  • strings -td partition.dd |grep keyword
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What is the sleuthkit version of the strings command and what benefits does it have?

Sleuthkit has the "srch_strings" version of strings command.

The offset is in bytes, can calculate the block and find the inode.

You can feed meta data into an SQL database for fast searching:

  • tsk_loaddb image.dd

Searching and indexing is very advanced in commercial tools

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What is a hash database and why is it usefull?

In a hash database the hashes of individual files are stored. This can be used to:

  • find or ignore matching file sets using hash values
  • There are lists available of hashes of system files so they can be excluded from searches and analysis
    • NSLR is an example of a list of known "good" files.
  • Own custom databases of hashes of good and bad files can be created.

Some agencies have special hash databases to find illegal materials

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What does the sleuthkit sorter do?

The sleuthkit sorter :

  • creates a report of identified files (incl. deleted)
    • sorter -d . partition.dd
  • Sorted extraction of files
    • sorter -s -d . partition.dd
  • Sorter only includeing hash database
    • sorter -a contraband.db -d . partition.dd
  • Sorter excluding NSRL database
    • sorter - nsrl_db -d . partition.dd

It is configurable perl script that uses multiple TSK tools.