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From: Michael Wojcik on 5 Feb 2010 10:00
Alistair wrote:
> On Feb 4, 4:02 pm, Michael Wojcik <mwoj...(a)newsguy.com> wrote:
>> Alistair wrote:
>>
>>> If you don't have the file layouts and probably you don't have report
>>> or screen shots then you probably won't be able to resolve the issue.
>>
>> In other words, this is a forensic exercise. It's impossible to
>> reconstruct the data format with guaranteed complete accuracy in the
>> general case, and difficult in many specific cases. You'd need to
>> perform a cost/benefit analysis to determine how much effort is
>> reasonable to expend on it.
>
> The application of a cost benefit analysis is quite a good idea as I
> found the effort excessive (but I had very little choice in the
> matter).

And that may be the case for the OP here, too. Of course, having
"little choice" should be considered a benefit, in the cost/benefit
analysis - that is, avoiding the consequences (whatever they may be)
of not doing the job compensates for the effort.

> I think SOMEGUY is banging his head against a brick wall (ce taper la
> tete contre le mur as they say in Germany) without the copylibs.

Certainly it makes the problem much worse. Sometimes the record
structure can be reconstructed by comparing known data to the file
contents - at *this* offset we have a last name, and here we have an
account number, etc. But it may be necessary to follow the execution
of a program that uses the file to determine what individual fields
correspond to.

We see a lot of this sort of thing in security research, as
researchers often have to deal with undocumented interfaces, security
by obscurity, program state at random points in its execution, and
code in object form only. If you read vulnerability disclosure
research, for example, you'll see it's quite typical in the field to
determine data formats by tracing program execution. Not everyone's
cup of tea.

--
Michael Wojcik
Micro Focus
Rhetoric & Writing, Michigan State University
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