Archive for June 9th, 2008

Data Recovery with Memory Dump Analysis

Monday, June 9th, 2008

My friend was typing a long message in IE to one of his old schoolmates that he had just found on Internet. He spent about an hour writing and rewriting and when finally hit the Send button he got a page saying that connection was probably lost. Going back in URL history brought the empty edit box and all data was lost. Or was it? He called me and I immediately advised him to save a crash dump of iexplore.exe using Task Manager (Vista). I also asked him for a word he used to start his message. It was “Hello” in Russian. I got his dump file and opened it in WinDbg. Because the language of his message was Russian I assumed that it was still there in local buffers or heap entries in UNICODE format so I typed “ello” in Notepad and saved this in a Unicode text file. Loading it in a binary editor (I used Visual C++) showed the following sequence of bytes:

40 04 38 04 32 04 35 04 42 04

Then I did a search in WinDbg for this sequence from the first loaded module address till the end of user space:

0:000> lm
start    end        module name
003c0000 0045b000   iexplore
[...]

0:000> s 003c0000 L?7FFFFFFF 40 04 38 04 32 04 35 04 42 04
[...]
048971e4 40 04 38 04 32 04 35 04-42 04 2c 00 20 00 1c 04  @.8.2.5.B.,. ...
[...]
08530fe4 40 04 38 04 32 04 35 04-42 04 2c 00 20 00 1c 04 @.8.2.5.B.,. ...
[...]
201ea65c 40 04 38 04 32 04 35 04-42 04 2c 00 20 00 1c 04 @.8.2.5.B.,. ...
[...]
 

The number of found entries was big and I decided to output every entry into a file using the following script: 

.foreach ( address { s-[1]b 003c0000 L?7FFFFFFF 40 04 38 04 32 04 35 04 42 04 }) {.writemem c:\dmitry\ieout${address}.txt ${address}-10 ${address}+1000}

I got numerous files:

C:\dmitry>dir ieout*.txt
[...]
09/06/2008  08:53               4112 ieout0x048971e4.txt
09/06/2008  08:53               4112 ieout0x0489784c.txt
09/06/2008  08:53               4112 ieout0x0489b854.txt
09/06/2008  08:53               4112 ieout0x0489bc5c.txt
[...]

I combined all of them into one big file and sent it to my friend:

C:\dmitry>type ieout0x*.txt >ieoutall.txt

The file contained not only the final message but all intermediate typing histories too. He was very happy.

- Dmitry Vostokov @ DumpAnalysis.org -

Memoidealism

Monday, June 9th, 2008

Looking at memory dumps every day and writing about them has an unfortunate implication: every state of the world looks like a gigantic memory dump to me. Everything is memory and every state is memory dump. The current state of the world is an infinite (or an immense) number of memuons*. Infinite can be any cardinal number greater or equal to that of natural numbers. In any case we can say it is N bits where this number is either finite or ∞. Therefore we have 2N possible memory states (S). The set of possible transitions between them (S -> S) has the number of 2N ^ 2N elements. Which is the memory itself and we have transitions between its states too. Ad infinitum we have a limiting process from which arises the perceived flow of events. Anyway there is much to elaborate here. I’ll come back to this later.

(*) Memuon is an indivisible entity similar to a bit of information.

This is my current philosophy :-) I’m dead serious.

- Dmitry Vostokov @ DumpAnalysis.org -