Re: [sleuthkit-users] TSK-4.4 and SlackFiles

[Brian C. <ca...@sl...>]

Ughh.  I need to better start documenting these scenarios because I always
get confused by them too.

I think you've found an issue and I created #756 (
https://github.com/sleuthkit/sleuthkit/issues/756) to address this.

The summary of your specific questions are:
- VSC is strange because WIndows seems to treat it differently and lies
about initsize.  It has initsize of 0, but a file size that is equal to the
allocsize.
- In the log file case, 4096 has been initialized, but the allocated size
of the file is 2MB.








On Tue, Jan 31, 2017 at 7:26 PM, Luís Filipe Nassif <lfc...@gm...>
wrote:

> Thank you, Brian, for your explanation! No problem for our application,
> just curious to know if it was a bug or, if not, why it is there.
>
> But, currently, no slack files are created for VSC files and other files
> with initsize smaller than allocated size. I thought slack is created only
> when allocated > logical size (based on line 1001 of db_sqlite.cpp)
>
> And is the allocated size 4096 from istat output? I do not know where the
> slack size of 2.026.496 bytes came from...
>
> 2017-01-31 18:05 GMT-02:00 Brian Carrier <ca...@sl...>:
>
>> Actually, making this decision could incur some significant overhead for
>> a step that (at least in Autopsy) we try to keep as fast as possible.  Is
>> your application impacted by the fact that there is a large and empty slack
>> file or were you just curious if it was a bug?
>>
>>
>>
>> On Tue, Jan 31, 2017 at 2:54 PM, Brian Carrier <ca...@sl...>
>> wrote:
>>
>>> Yea, this looks like "VDL Slack".  Same general idea as in Issue 466 (
>>> https://github.com/sleuthkit/sleuthkit/issues/466), but in this case
>>> the file has 1K of initialized size.
>>>
>>> I suppose this "slack" file is a bit wasted though because no blocks
>>> were allocated to it. So, there will be no real content for it.
>>>
>>> I'll make an internal story to keep track of this and maybe Ann will be
>>> able to take a look at not making these if they are going to be all for
>>> address 0.
>>>
>>>
>>>
>>> On Tue, Jan 31, 2017 at 10:55 AM, Luís Filipe Nassif <
>>> lfc...@gm...> wrote:
>>>
>>>> Hi Brian,
>>>>
>>>> Thank you very much for your attention. The output of
>>>> FsContent.getMetaDataText() (equals to istat right?) is below. The
>>>> system.LOG-slack size is 2.026.496 bytes and system.LOG size is 1024 bytes.
>>>>
>>>> details of /img_PC-HP.dd/vol_vol2/WINDOWS/system32/config/system.LOG-sl
>>>> ack
>>>>
>>>> MFT Entry Header Values:
>>>> Entry: 4106        Sequence: 1
>>>> $LogFile Sequence Number: 79246281526
>>>> Allocated File
>>>> Links: 1
>>>>
>>>> $STANDARD_INFORMATION Attribute Values:
>>>> Flags: Hidden, Archive
>>>> Owner ID: 0
>>>> Security ID: 281  (S-1-5-32-544)
>>>> Last User Journal Update Sequence Number: 105272096
>>>> Created: 2004-09-02 08:00:12.000000000 (Hora oficial do Brasil)
>>>> File Modified: 2011-09-16 14:33:38.375000000 (Hora oficial do Brasil)
>>>> MFT Modified: 2011-09-16 14:33:38.375000000 (Hora oficial do Brasil)
>>>> Accessed: 2011-09-16 14:33:38.187500000 (Hora oficial do Brasil)
>>>>
>>>> $FILE_NAME Attribute Values:
>>>> Flags: Hidden, Archive
>>>> Name: system.LOG
>>>> Parent MFT Entry: 3982 Sequence: 2
>>>> Allocated Size: 4096   Actual Size: 1024
>>>> Created: 2004-09-02 08:00:12.000000000 (Hora oficial do Brasil)
>>>> File Modified: 2004-09-02 08:00:12.000000000 (Hora oficial do Brasil)
>>>> MFT Modified: 2004-09-02 08:00:12.000000000 (Hora oficial do Brasil)
>>>> Accessed: 2004-09-02 08:00:12.000000000 (Hora oficial do Brasil)
>>>>
>>>> $ATTRIBUTE_LIST Attribute Values:
>>>> Type: 16-0 MFT Entry: 4106 VCN: 0
>>>> Type: 48-4 MFT Entry: 4106 VCN: 0
>>>> Type: 128-0 MFT Entry: 40678 VCN: 0
>>>>
>>>> Attributes:
>>>> Type: $STANDARD_INFORMATION (16-0)   Name: N/A   Resident   size: 72
>>>> Type: $ATTRIBUTE_LIST (32-5)   Name: N/A   Resident   size: 96
>>>> Type: $FILE_NAME (48-4)   Name: N/A   Resident   size: 86
>>>> Type: $DATA (128-6)   Name: N/A   Non-Resident   size: 1024  init_size:
>>>> 1024
>>>> 847844 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0 0
>>>> 0 0 0 0 0 0 0
>>>>
>>>> 2017-01-31 12:56 GMT-02:00 Brian Carrier <ca...@sl...>:
>>>>
>>>>> Hi Luis,
>>>>>
>>>>> My guess is that it's a file that has preallocated a large amount of
>>>>> space, but that has not fully used it yet. NTFS allows this.  If you read
>>>>> the file, TSK will only show you the space that is used.  Reading the
>>>>> slack, gives you the rest.
>>>>>
>>>>> If you run 'istat' on one of these files and send it along, we can
>>>>> confirm.
>>>>>
>>>>> thanks,
>>>>> brian
>>>>>
>>>>>
>>>>> On Tue, Jan 31, 2017 at 7:04 AM, Luís Filipe Nassif <
>>>>> lfc...@gm...> wrote:
>>>>>
>>>>>> Hi folks,
>>>>>>
>>>>>> I am upgrading to tsk-4.4 to benefit from the new support to
>>>>>> slackfiles from java bindings. But I noticed some slackfiles larger than
>>>>>> the cluster size (4k) are created in database. Some of them have megabytes
>>>>>> of size and its contents are accessible. Is it expected to have slackfiles
>>>>>> larger than cluster size? Could someone explain?
>>>>>>
>>>>>> Thanks,
>>>>>> Luis Nassif
>>>>>>
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>>>>>>
>>>>>
>>>>
>>>
>>
>