Difference between pages "JTAG Huawei TracFone M866C" and "Forensic Live CD issues"

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(Huawei M866C JTAG Procedure)
 
m (Incorrect write-blocking approach)
 
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== Huawei  M866C - Ascend Y ==
+
== The problem ==
  
This phone is supported by the Tracfone. This uses a Qualcomm 7625A 800 MHz (S1) Processor and comes standard with Android version 2.3. This phone is unsupported by RIFF Box for the JTAG process for resurrector.  
+
[[Live CD|Forensic Live CDs]] 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. Unfortunately, community-developed distributions are no exception here. Finally, it turns out that many Linux-based forensic Live CDs are not tested properly and there are no suitable test cases published.
  
{| border="1" cellpadding="2"
+
== Another side of the problem ==
|-
+
| [[ File:Huawei-tracfone-m866c-front.JPG | 200px ]]
+
|-
+
|}
+
  
=== Getting Started ===
+
Another side of the problem of insufficient testing of forensic Live CDs is that many users do not know what happens "under the hood" of the provided operating system and cannot adequately test them.
  
 +
=== Example ===
  
What you need:
+
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).
  
 +
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.
  
# Riff Box
+
== Problems ==
# USB to Micro USB cord
+
  
 +
Each problem is followed by a list of distributions affected (currently this list is not up-to-date).
  
=== NAND Dump Procedure ===
+
=== Journaling file system updates ===
  
 +
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:
  
# Remove the battery and peel the label back to expose the TAPS.
+
{| class="wikitable" border="1"
# Connect the RIFF box to the PC via USB.
+
|-
# Connect the RIFF box to the PCB via the JTAG pins.
+
!  File system
# Connect the PCB to a Micro USB cord and power via a power supply.
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!  When data writes happen
# Start the "RIFF box" software.
+
!  Notes
# Power the PCB.
+
|-
# Dump the NAND.
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|  Ext3
 +
|  File system requires journal recovery
 +
|  To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
 +
|-
 +
|  Ext4
 +
|  File system requires journal recovery
 +
|  To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
 +
|-
 +
|  ReiserFS
 +
|  File system has unfinished transactions
 +
|  "nolog" flag does not work (see ''man mount''). To disable journal updates: use "ro,loop" flags
 +
|-
 +
|  XFS
 +
|  Always (when unmounting)
 +
|  "norecovery" flag does not help (fixed in recent 2.6 kernels). To disable data writes: use "ro,loop" flags.
 +
|}
  
 +
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).
  
The TAPS are located under the battery, behind the Huawei phone label. The phone will be powered by a Micro USB cord from an AC battery charger.
+
[[Image:ext3 recovery.png|thumb|right|[[Helix3]]: damaged Ext3 recovery during the boot]]
  
 +
List of distributions that recover Ext3 (and sometimes Ext4) file systems during the boot:
  
The TAPS order is as follows:
+
{| class="wikitable" border="1"
 +
|-
 +
!  Distribution
 +
!  Version
 +
|-
 +
|  Helix3
 +
|  2009R1
 +
|-
 +
|  SMART Linux (Ubuntu)
 +
|  2010-01-20
 +
|-
 +
|  FCCU GNU/Linux Forensic Boot CD
 +
|  12.1
 +
|-
 +
|  SPADA
 +
|  4
 +
|-
 +
|  DEFT Linux
 +
|  7
 +
|}
  
# 1=Not Used
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=== Orphan inodes deletion ===
# 2=TCK
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# 3=GND
+
# 4=TMS
+
# 5=TDI
+
# 6=TDO
+
# 7=RTCK
+
# 8=TRST
+
# 9=NRST
+
  
 +
When mounting Ext3/4 file systems all orphan inodes are removed, even if "-o ro" mount flag was specified. Currently, there is no specific mount flag to disable orphan inodes deletion. The only solution here is to use "-o ro,loop" flags.
  
{| border="1" cellpadding="2"
+
=== Root file system spoofing ===
|-
+
| [[ File:Hauwei_U866C_TAPS.jpg | 600px ]]
+
|-
+
|}
+
  
 +
''See also: [[Early userspace | early userspace]]''
  
After the wires are connected to the board, the phone is powered by the USB connection. Plug the Micro USB into the USB connection on the device and then plug the phone into a wall outlet. The phone should respond with the vibrator switch activating for less than a second.  
+
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.
  
 +
[[Image:Grml.png|thumb|right|[[grml]] mounted root file system from the [[hard drive]]]]
  
Launch the Riff Box JTAG Manager and use the following settings:
+
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.
  
 +
List of Ubuntu-based distributions that allow root file system spoofing:
  
* JTAG TCK Speed = RTCK
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{| class="wikitable" border="1"
* Resurrector Settings= Huawei U8655
+
|-
* Auto FullFlash size
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!  Distribution
 +
!  Version
 +
|-
 +
|  Helix3
 +
|  2009R1
 +
|-
 +
|  Helix3 Pro
 +
|  2009R3
 +
|-
 +
|  CAINE
 +
|  1.5
 +
|-
 +
|  DEFT Linux
 +
|  5
 +
|-
 +
|  Raptor
 +
|  2.0
 +
|-
 +
|  BackTrack
 +
|  4
 +
|-
 +
|  SMART Linux (Ubuntu)
 +
|  2010-01-20
 +
|-
 +
|  FCCU GNU/Linux Forensic Boot CD
 +
|  12.1
 +
|}
  
{| border="1" cellpadding="2"
+
Vulnerable Knoppix-based distributions include: SPADA, LinEn Boot CD, BitFlare.
|-
+
| [[ File:M866C_setting.jpg | 800px ]]
+
|-
+
|}
+
  
 +
[http://anti-forensics.ru/ Anti-Forensics.Ru project] [http://digitalcorpora.org/corp/aor/drives/ 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]).
  
Advanced Settings:
+
=== Swap space activation ===
  
 +
''Feel free to add information about swap space activation during the boot in some distributions''
  
* Ignore Target IDCODE during Resurrection and DCC Loader operations
+
=== Incorrect mount policy ===
  
 +
==== rebuildfstab and scanpartitions scripts ====
  
{| border="1" cellpadding="2"
+
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).
|-
+
| [[ File:huawei-tracfone-m865c-riff-advanced-settings.jpg | 600px ]]
+
|-
+
|}
+
  
 +
=== Incorrect write-blocking approach ===
  
Then connect and get the ID, you should receive the dead body signal. Then read the memory.  
+
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 a block device to read-only mode does not guarantee that [http://oss.sgi.com/archives/xfs/2009-07/msg00213.html no write commands will be passed to the drive]. There were several other bugs related to writing on a read-only device in the past (like [https://lkml.org/lkml/2007/2/6/1 Ext3/4 orphan inodes deletion]). At present (Linux 3.14.2), kernel code still disregards read-only mode set on block devices in many places (it should be noted that setting a block device to read-only mode will efficiently write-protect the drive from programs running in userspace, while kernel and its modules still can write anything to the block device, regardless of the read-only mode).
  
 +
=== TRIM aka discard command ===
  
=== Notes ===
+
== External links ==
  
 +
* [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]
 +
* [http://www.computer-forensics-lab.org/pdf/Linux_for_computer_forensic_investigators.pdf Linux for computer forensic investigators: «pitfalls» of mounting file systems]
  
The phone has a 512 MB NAND flash memory chip which should take approximately 30 minutes to download.
+
[[Category:Live CD]]
 
+
 
+
=== References ===
+
*http://www.phonescoop.com/phones/phone.php?p=3308
+
*http://www.riffbox.org/
+

Revision as of 18:02, 15 June 2014

The problem

Forensic Live CDs 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. Unfortunately, community-developed distributions are no exception here. Finally, it turns out that many Linux-based forensic Live CDs are not tested properly and there are no suitable test cases published.

Another side of the problem

Another side of the problem of insufficient testing of forensic Live CDs is that many users do not know what happens "under the hood" of the provided operating system and cannot adequately test them.

Example

For example, 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).

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.

Problems

Each problem is followed by a list of distributions affected (currently this list is not up-to-date).

Journaling file system updates

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:

File system When data writes happen Notes
Ext3 File system requires journal recovery To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
Ext4 File system requires journal recovery To disable recovery: use "noload" flag, or use "ro,loop" flags, or use "ext2" file system type
ReiserFS File system has unfinished transactions "nolog" flag does not work (see man mount). To disable journal updates: use "ro,loop" flags
XFS Always (when unmounting) "norecovery" flag does not help (fixed in recent 2.6 kernels). To disable data writes: use "ro,loop" flags.

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 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).

Helix3: damaged Ext3 recovery during the boot

List of distributions that recover Ext3 (and sometimes Ext4) file systems during the boot:

Distribution Version
Helix3 2009R1
SMART Linux (Ubuntu) 2010-01-20
FCCU GNU/Linux Forensic Boot CD 12.1
SPADA 4
DEFT Linux 7

Orphan inodes deletion

When mounting Ext3/4 file systems all orphan inodes are removed, even if "-o ro" mount flag was specified. Currently, there is no specific mount flag to disable orphan inodes deletion. The only solution here is to use "-o ro,loop" flags.

Root file system spoofing

See also: early userspace

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.

grml mounted root file system from the hard drive

Currently, Casper may select fake root file system image on evidentiary media (e.g. 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.

List of Ubuntu-based distributions that allow root file system spoofing:

Distribution Version
Helix3 2009R1
Helix3 Pro 2009R3
CAINE 1.5
DEFT Linux 5
Raptor 2.0
BackTrack 4
SMART Linux (Ubuntu) 2010-01-20
FCCU GNU/Linux Forensic Boot CD 12.1

Vulnerable Knoppix-based distributions include: SPADA, LinEn Boot CD, BitFlare.

Anti-Forensics.Ru project released several ISO 9660 images used to test various Linux Live CD distributions for root file system spoofing (description for all images is here).

Swap space activation

Feel free to add information about swap space activation during the boot in some distributions

Incorrect mount policy

rebuildfstab and scanpartitions scripts

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).

Incorrect write-blocking approach

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 a block device to read-only mode does not guarantee that no write commands will be passed to the drive. There were several other bugs related to writing on a read-only device in the past (like Ext3/4 orphan inodes deletion). At present (Linux 3.14.2), kernel code still disregards read-only mode set on block devices in many places (it should be noted that setting a block device to read-only mode will efficiently write-protect the drive from programs running in userspace, while kernel and its modules still can write anything to the block device, regardless of the read-only mode).

TRIM aka discard command

External links