Unknown Master List .dat file, issues retrieving information - file

Question

I come to you completely stumped. I do some side work for a company that uses an old DOS based program to input and retrieve data. This is a legacy piece of software, and they have since moved to either QuickBooks or Outlook for all of their address or billing related needs. However there have been some changes made, and they work with this database fairly regularly. Since the computer that this software is on, is running XP (and none of the other computers in the office can run it) they're looking to phase this software out for when the computer inevitably explodes.
TLDR; I have an old .csv file (roughly two years) that has a good chunk of information on it, but again it's two years old. I have another file called ml.dat (I'm assuming masterlist.dat) that's in the same folder as this legacy software. I open it with notepad and excel and am presented with information like this:
S;Û).;PÃS;*p(â'a,µ,
The above chunk of text is recognized much less within notepad or excel. It's a lot more of the unrecognized squares.
Some of the information is actually readable however. I can for example read the occasional town name, or person's name but I'm unable to get all of the information since there's a lot missing. Perhaps the data isn't in unicode or something? I have no idea. Any suggestions? I'm ultimately trying to take this information and toss it into either quickbooks or outlook.
Please help!
Thanks
Edit: I'm guessing the file might be encrypted since .dat's are usually clear text? Any thoughts?

Answer 1

.DAT files can be anything, they are usually just application data. Since there is readable text, then it is very unlikely that this file is encrypted. Instead you are seeing ASCII representations of the bytes of other content. http://www.asciitable.com/ Assuming single byte values, the number 77 might appear in the file somewhere as M.
Your options:
Search for some utility to load and translate the dat file for that application.
Set up an appropriate dos emulator so you can run this application on another box, or even a virtual machine running freedos or something.
Figure out the file format and then write a program to translate the data.
For #3, you can attach a debugger to the application to trace how the file is read and written. Alternatively you can try to figure out record boundaries (if all the records are the same size, then things are a little bit easier.) Then you can use known values to try to find field boundaries. If you can find (or reverse compile) the source code, then that could also give you insight into the file format.
1 is your best bet, and #2 will buy you some time so that you don't need that original machine anymore. #3 would likely be something to outsource.
If you can find the source or file format, then you just recreate whatever data structure was dumped to the file and read the file into it.
To find which exe opens it, you can do something like:
for %f in (*.exe) do find "ml.dat" %f -c
Assuming the original application was written in C then there would be code something like this to read the first record from the file:
struct SecretData
{
int first;
double money;
char city[10];
};
FILE* input;
struct SecretData secretdata;
input = fopen("ml.dat", "rb");
fread(&data, sizeof(data), 1, input);
fclose(input);
(The file would have been written with fwrite.) Basically you need to figure out the innards of the SecretData structure to be able to read the file.
There likely wasn't a separate utility used to make the file, dumping data and reading it back from a file is relatively easy in most languages.