Forensic Tools

Forensic Tools
Forensic tools to assist with an investigation

CnW Recovery software has many tools built in to assist with both data recovery, and forensic reports on disks that have become corrupted, deleted, or otherwise changed.

Any forensic investigation has to be done extremely carefully if the evidence extracted will have any use in court.

Key elements are
Continuity of evidence and good forensic practice
No corruption or modification of data
No possible data missed
Extraction of unallocated space and slack space
Repeatable recovery of data
Jpg file size
No possible data contamination
Comprehensive logs
Use of hashing (MD5 and SHA-256) on files extracted
Good logs of operations and procedures
Overwritten sectors should be located
Slack space recovery
Locate which file a sector relates to
File fragment runs

Working on potentially corrupted, or damage disks brings another level of complexity into examination of disks. The notes below give guide lines on how to approach different types of disks, and media, in different states of corruption
Forensic report - log of disk parameters and errors found
General job report in XML - summary of all stages of a recovery
NTFS Forensic - how to investigate an NTFS disk
FAT forensic - tools are reports on FAT disks
Logs - full description of program log
MFT Parse - display fields within an MFT
Forensic CD
DVD properties
Image hashing, the ability to select and recover images based on MD5 value
Raw recovery, when there is no valid operating system
Forensic file formats, E01 and VM Virtual disk format
Data carving, for fragmented files in unallocated data areas
Search disk - search for string any were on a disk, including NTFS compressed sectors
Keyword Search
Good forensic practice
Stolen chip - investigate if a chip had been stolen
Disk scan - visual display of all sectors by type

Forensic Logs
Logging is a very important point in any forensic inquiry, and data restoration. It is essential to know where data has been found, on what media, date etc. The basis of this information is stored in the log for CnW Recovery. There is a separate log file generated for each restore, giving media details, as well as details for each file or error detected. The logs may be sorted by clicking on the column header for any column. Logs may also be exported as a .csv file, and so can be processed in many common applications, such as Access - or for shorter logs, in Excel.

Another very important aspect of any forensic investigation, and recovery of files from a disk, is to determine what has not been recovered, such as deleted files, partially overwritten files, or files left behind from a previous formatting of a disk. There are also sections of a hard disk where a cluster has been allocated to a file, but the file does not use the whole cluster. This is called slack space, and can often contain fragments of data from previous files. On NTFS, the situation can be slightly more complex, as short files are stored as part of the MFT, and so slack space can be part of any MFT that is not a full 0124 bytes in length.

Files in most operating systems can be fragmented - the CnW Log will keep a count of the number of fragments in any file. It is even possible to select a sector and determine which file it was part of.

Locating a sector
A very useful feature within a forensic analysis of a disk is to determine which file a certain sector belongs to. In the Log function, the search button can be used. This will indicate the file for a certain sector. This does include files that have been fragmented, though it only checks the first 64 fragments - it should be noted that not many files have typically more than a few fragments

Partially failed disks
When analysing disks there are often problems due the disk having partial failure, or a large number of unreadable sectors. The solution within CnW Recovery software is to create a disk image, but image may be made up in multiple sections. If an area of disk cannot be read, the image may be continued in a different area of the disk. The recovery routines will work with the compiled image and still recover files. There are also tools to assist in imaging just the directory area of a disk, and the failed disk can still be used a shadow drive for areas of the disk not actually imaged.
File carving
With raw file recovery, fragmented files are not recovered correctly. To overcome this problem, automatic file carving routines are being built into the program to process fragmented files, and assemble a valid working file. The process works by first extracting all known good files, and working on the unallocated space. Once a file start is found, then the unallocated space is searched for extra fragments.

Forensic options
Certain features of the CnW Recovery program are only available when the forensic options package has been purchased.

The features that are only part of the forensic package include the following
UDF disks, scanning of separate write sessions
Hash values in the log
Slack space recovery
Disk scan - visual image of disk use
Unerase of CD-RW disks
Enhanced log of errors detected on recovery
Reads system files such as $logfile $bitmap $boot $secure $MFT
Reading Encase compatible EWF files, E01 etc