Difference between pages "Forensic Live CD issues" and "User talk:Bethan Williams"

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== The problem ==
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Bethan is Head of Marketing at CY4OR and has worked for the Company for 5 years. With over 12 years experience in both B2B and B2C market sectors, I have a varied skill set ranging from more traditional marketing techniques through to online and social media campaign management.
  
[[Tools#Forensics_Live_CDs | Forensic Linux Live CD distributions]] are widely used during computer forensic investigations. Currently, many vendors of such Live CD distributions spread false claims that their distributions "do not touch anything", "write protect everything" and so on. Community-developed distributions are no exception here, unfortunately. Finally, it turns out that many forensic Linux Live CD distributions are not tested properly and there are no suitable test cases developed.
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At CY4OR http://www.cy4or.co.uk I am responsible for creating, communicating and delivering customer value through creative sales and marketing .
  
== Another side of the problem ==
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Specialties
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CY4OR is a UK based digital forensics, information assurance and edisclosure firm with over 9 years experience in digital evidence. We provide a leading edge service to legal and professional firms, corporate companies, public sector organisations and law enforcement agencies.
  
Another side of the problem of insufficient testing of forensic Live CD distributions is that many users do not know what happens "under the hood" of such distributions and cannot adequately test them.
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'''Services'''
 
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Computer Forensics
=== Example ===
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Audio Video Forensics
 
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Data Collection
For example, [http://forensiccop.blogspot.com/2009/10/forensic-cop-journal-13-2009.html ''Forensic Cop Journal'' (Volume 1(3), Oct 2009)] describes a test case when an Ext3 file system was mounted using "-o ro" mount flag as a way to write protect the data. The article says that all tests were successful (i.e. no data modification was found after unmounting the file system), but it is known that damaged (i.e not properly unmounted) Ext3 file systems cannot be write protected using only "-o ro" mount flags (write access will be enabled during file system recovery).
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eDisclosure
 
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Mobile Phone Forensics
And the question is: will many users test damaged Ext3 file system (together with testing the clean one) when validating their favourite forensic Live CD distribution? My answer is "no", because many users are unaware of such traits.
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Cell Site Analysis
 
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Incident Response
== Problems ==
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Vulnerability Assessment
 
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Penetration Testing
Each problem is followed by an up to date list of distributions affected.
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Forensic Readiness Planning
 
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=== Journaling file system updates ===
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When mounting (and unmounting) several journaling file systems with only "-o ro" mount flag a different number of data writes may occur. Here is a list of such file systems:
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{| class="wikitable" border="1"
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|-
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!  File system
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!  When data writes happen
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!  Notes
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|-
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|  Ext3
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|  File system requires journal recovery
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|  To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
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|-
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|  Ext4
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|  File system requires journal recovery
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|  To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
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|-
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|  ReiserFS
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|  File system has unfinished transactions
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|  "nolog" flag does not work (see ''man mount''). To disable journal updates: use "ro,loop" flags
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|-
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|  XFS
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|  Always (when unmounting)
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|  "norecovery" flag does not help (fixed in recent 2.6 kernels). To disable data writes: use "ro,loop" flags.
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|}
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Incorrect mount flags can be used to mount file systems on evidentiary media during the boot process or during the file system preview process. As described above, this may result in data writes to evidentiary media. For example, several Ubuntu-based forensic Live CD distributions mount and recover damaged Ext3/4 file systems on fixed media (e.g. hard drives) during execution of [http://en.wikipedia.org/wiki/Initrd ''initrd''] scripts (these scripts mount every supported file system type on every supported media type using only "-o ro" flag in order to find a root file system image).
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[[Image:ext3 recovery.png|thumb|right|[[Helix3]]: damaged Ext3 recovery during the boot]]
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List of distributions that recover Ext3 (and sometimes Ext4) file systems during the boot:
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{| class="wikitable" border="1"
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|-
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!  Distribution
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!  Version
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|-
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|  Helix3
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|  2009R1
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|-
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|  SMART Linux (Ubuntu)
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|  2010-01-20
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|-
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|  FCCU GNU/Linux Forensic Boot CD
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|  12.1
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|-
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|  SPADA
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|  4
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|}
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=== Root file system spoofing ===
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Most Ubuntu-based forensic Live CD distributions use Casper (a set of scripts used to complete initialization process during early stage of boot). Casper is responsible for searching for a root file system (typically, an image of live environment) on all supported devices (because a bootloader does not pass any information about device used for booting to the kernel), mounting it and executing ''/sbin/init'' program on a mounted root file system that will continue the boot process. Unfortunately, Casper was not designed to meet computer forensics requirements and is responsible for damaged Ext3/4 file systems recovery during the boot (see above) and root file system spoofing.
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[[Image:Grml.png|thumb|right|[[grml]] mounted root file system from the [[hard drive]]]]
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Currently, Casper may select fake root file system image on evidentiary media (e.g. [[Hard Drive|HDD]]), because there are no authenticity checks performed (except optional UUID check for a possible live file system), and this fake root file system image may be used to execute malicious code during the boot with root privileges. Knoppix-based forensic Live CD distributions are vulnerable to the same attack.
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List of Ubuntu-based distributions that allow root file system spoofing:
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{| class="wikitable" border="1"
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|-
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!  Distribution
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!  Version
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|-
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|  Helix3
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|  2009R1
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|-
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|  Helix3 Pro
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|  2009R3
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|-
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|  CAINE
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|  1.5
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|-
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|  DEFT Linux
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|  5
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|-
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|  Raptor
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|  2.0
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|-
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|  BackTrack
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|  4
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|-
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|  SMART Linux (Ubuntu)
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|  2010-01-20
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|-
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|  FCCU GNU/Linux Forensic Boot CD
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|  12.1
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|}
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Vulnerable Knoppix-based distributions include: SPADA, LinEn Boot CD, BitFlare.
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[http://anti-forensics.ru/ Anti-Forensics.Ru project] [http://digitalcorpora.org/corp/images/aor/ released several ISO 9660 images] used to test various Linux Live CD distributions for root file system spoofing (description for all images is [http://anti-forensics.ru/casper/ here]).
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=== Swap space activation ===
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''Feel free to add information about swap space activation during the boot in some distributions''
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=== Incorrect mount policy ===
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==== rebuildfstab and scanpartitions scripts ====
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Several forensic Linux Live CD distributions (Helix3 2009R1, Helix3 Pro 2009R3, old versions of CAINE, old versions of grml) use rebuildfstab and scanpartition scripts to create entries for attached devices in ''/etc/fstab''. Some versions of these scripts use wrong wildcards while searching for available block devices (''/dev/?d?'' instead of ''/dev/?d*''), this results in missing several "exotic" devices (like /dev/sdad, /dev/sdad1, etc) and in data writes when mounting them (because fstab lacks of read-only mount options for these devices).
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=== Incorrect write-blocking approach ===
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Some forensic Linux Live CD distributions rely on [[hdparm]] and [[blockdev]] programs to mount file systems in read-only mode (by setting the underlying block device to read-only mode). Unfortunately, setting the block device to read-only mode does not guarantee that [http://archives.free.net.ph/message/20090721.105120.99250e3f.en.html no write commands will be passed to the drive].
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== External links ==
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* [http://www.computer-forensics-lab.org/pdf/Linux_for_computer_forensic_investigators_2.pdf Linux for computer forensic investigators: problems of booting trusted operating system]
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* [http://www.computer-forensics-lab.org/pdf/Linux_for_computer_forensic_investigators.pdf Linux for computer forensic investigators: «pitfalls» of mounting file systems]
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[[Category:Live CD]]
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Revision as of 04:41, 17 February 2012

Bethan is Head of Marketing at CY4OR and has worked for the Company for 5 years. With over 12 years experience in both B2B and B2C market sectors, I have a varied skill set ranging from more traditional marketing techniques through to online and social media campaign management.

At CY4OR http://www.cy4or.co.uk I am responsible for creating, communicating and delivering customer value through creative sales and marketing .

Specialties CY4OR is a UK based digital forensics, information assurance and edisclosure firm with over 9 years experience in digital evidence. We provide a leading edge service to legal and professional firms, corporate companies, public sector organisations and law enforcement agencies.

Services Computer Forensics Audio Video Forensics Data Collection eDisclosure Mobile Phone Forensics Cell Site Analysis Incident Response Vulnerability Assessment Penetration Testing Forensic Readiness Planning