After quite a bit of searching and trying different things, I am stumped on how to get mym to work (as found here: http://sourceforge.net/projects/mym/). I was wondering if anyone has a very simple list of actions needed to get this to work. I think my main trouble is installing zlib. I don't understand how to actually install it or work with it. I have tried to use Microsoft Visual C++ Express 2010 but then only the debug versions are compiled. That means when I try to use the mex function in matlab it gives me the error:
Error: Could not detect a compiler on local system
which can compile the specified input file(s)
I just don't understand the process and everywhere I look it says something different. I have tried multiple versions of each all of the programs involved and nothing seems to work. Any help would be greatly appreciated.
Do:
mex -setup
from the command line to define your compiler on your system. Once you do that then Matlab will correctly locate the compiler and build the mex libraries it needs.
See:
http://www.mathworks.com/help/matlab/matlab_external/building-mex-files.html
Related
I am currently trying to solve a reversing challenge, where c code is compiled for a 32bit linux system.
To solve this challenge I am trying to make use of ghidra but am faced with a few issues. A bit of a summary what I have done up to this point:
I have two OS available to me, one 64bit Linux System on my Laptop and this 64bit Windows 10. Apparantly the programm was compiled with gcc without a -g option making ghidra fail to debug the programm. Manually debugging it with gdb in Terminal is possible but terrible to use (at least for me).
So all I can do is look at the assembler code in the CodeBrowser of Ghidra and its respective decomipled c code. With that I got to understand that some of the instructions are decrypted during the runtime of the programm and in order to further analyse the code, I want to be able to execute parts of the instructions to slowly but surely decrypt and understand the hidden parts of the programm.
That being said, the only issue here is that I do not know how I can do that. I have noticed that ghidra has the ability to run java code, but all the examples I looked at that were provided by ghidra allow me to only patch hardcoded instructions into the programm but not to actually execute/evaluate them.
My specific issue at hand is following part of the programm (green marked part):
Ghidra has all the knowledge it needs to execute this part and I just do not know how to do that. I could of cause do it by hand, but that is just boring and not really why I am doing these challenges and that is the same reason as why I am not looking for finished scripts that unpack this programm for me but for a way to execute my analysis.
Finally to summarize my question: I am asking for a way to execute the green marked decrypting part of the targeted programm in ghidra without starting the debugger (since the ghidra debugger keeps failing on me).
I think you are mixing up a few things here. You say:
the programm was compiled with gcc without a -g option making ghidra fail to debug the programm
The debug information added with -g makes it easier to analyze and debug a program because you have information that would have otherwise have to be recovered by reverse engineering. This should not have an influence on whether you can run the program under a debugger in the first place, and as you noted running it with gdb in the terminal works. The Ghidra debugger basically just runs gdb in the background and attaches to it to exchange information, so it should work.
You have a few options now:
1. Get the Ghidra Debugger to run with this binary
Whatever issue you are encountering with the Ghidra debugger is probably a valid question for https://reverseengineering.stackexchange.com/
From then on you can pursue your initial plan to solve this via debugging.
2. Write a GhidraScript to reimplement the decryption
Understand the basic idea of what you recognized correctly as some kind of decryption loop. Then you can use one of Ghidra's scripting options[0] to write a simple script that reimplements this decryption, but writes the decrypted values to the Ghidra memory directly.
Any scripting language will obviously include basic arithmetic operations like + -, and xor and loops, and the Ghidra API provides the functions byte getByte(Address address) and setByte(Address address, byte value). If you encounter any issues or API questions while writing this script that will also be a valid follow up question for the RE Stack Exchange.
This approach has the advantage that you can then statically analyse the resulting data inside Ghidra again, e.g. disassemble the resulting code.
[0] Ghidra natively supports Python 2.7 and Java based Scripts and a rudimentary Python REPL, but there are other options like Jupyter and Script based Kotlin or Ruby, Kotlin and Clojure Scripts
Does anyone ever succeeded in installing MAtConvNet under Octave ?
If so could you please let me know the steps to proceed ?
thanks and regards
Arno
I was just looking into this issue myself. I have reached a point in researching this where I feel the issues are too complicated for my own project and are not worth my time trying to finish running down. However, if someone else is determined to track this down, hopefully this information will help.
The basic problem comes down Octave only compiling to support 32-bit architectures even if you use the 64-bit installer. If you want Octave to support 64-bit, you need to compile from source using the appropriate compiling options. The other details are as follows.
MatConvNet appears to require a 64-bit system to compile.
http://www.vlfeat.org/matconvnet/mfiles/vl_compilenn/
MatConvNet detects system architecture in in the mex_cuda_config function in vl_compilenn.m:
https://github.com/vlfeat/matconvnet/blob/master/matlab/vl_compilenn.m
Octave's computer function is not a perfect analog to Matlab's function, so the mex_cuda_config function in vl_compilenn.m would need to be modified or Octave's computer function would need to be updated. More specifically, the computer function's handling of the 'arch' argument needs to be changed.
There may be other issues, but this is where I would start if I had the time to invest in trying to track this down.
I have downloaded the MySQL Connector/C driver from the official website, the version that I believe is supposed to be released next to 5.6.
I then obviously wanted to use the library so I wrote a small application. During linkage, I however got a strange linker errors saying it cannot find the functions mysql_library_init() and mysql_library_end().
When I use a command to check for the functions inside the library, nm /usr/lib64/mysql/libmysqlclient.a > ~/Desktop/symbols, I indeed cannot find the functions the linker mentioned.
The functions I do find however are mysql_server_init and mysql_server_end, which are according to the documentation, marked as deprecated. (There are more functions in there too)
What am I doing wrong? I am using version 6.1.2 of the driver.
It seems like the problem is that the documentation is ahead of the code.
I am a DBA, not a C programmer, though I dabble in server internals. If the file include/mysql.h in the MySQL Server source files is any indication, the mysql_server_* functions are the ones you're looking for.
/*
mysql_server_init/end need to be called when using libmysqld or
libmysqlclient (exactly, mysql_server_init() is called by mysql_init() so
you don't need to call it explicitely; but you need to call
mysql_server_end() to free memory). The names are a bit misleading
(mysql_SERVER* to be used when using libmysqlCLIENT). So we add more general
names which suit well whether you're using libmysqld or libmysqlclient. We
intend to promote these aliases over the mysql_server* ones.
*/
#define mysql_library_init mysql_server_init
#define mysql_library_end mysql_server_end
"We intend to promote these aliases over the mysql_server* ones."
They promoted them in the documentation, apparently.
It looks like Bug #65887 was a report of the same problem, that they never really got around to doing anything with.
You might also find MariaDB's implementation of the C API "for MariaDB and MySQL" to be a viable and perhaps more agreeably-licensed alternative.
I need to use the CobraToolbox for a course and I am wondering if it is compatible with Octave.
Even googling for this doesn't return much results..
Thanks in advance
Unless someone has published their results, you can't know without trying it. However, there is a very high likelihood that it will work on Octave, here's what Jordi has to say on this issue answering this question.
I am new to Octave and was wondering if it is possible to use matlab
toolboxes in Octave?
It depends on what you mean by "Matlab toolbox". If you mean the code
that came with Matlab, it's probably a license violation to use it
with Octave, assuming you can compile it for Octave when it's
necessary to compile.
If you mean free code out there you found on the internet that was
written for Matlab, it is likely it will work on Octave. Just try it.
If you need to compile mex files, the "mkoctfile --mex" command may be
of use.
If you want to have a rough equivalent of the Matlab toolboxes in
Octave, try the Octave-Forge packages:
My personal experience is that Octave has become extremely good at accepting Matlab code. I would hazard a guess that any time you spend setting up Octave and this toolbox will be worth it. Even the MEX files appear to have a portability mechanism. Unless they are using some very specific features like addpref for toolbox persistent data, it will slide right into Octave. Even if they are using the prefs, it could be modified to live in Octave.
I'm trying to translating the MySql C connector 6.02 headers to D, but I get some weird crashes.
My guess is I've made some mistakes on translating the structs or function (I'm not very good at C).
I used implib /system on the libmysql.dll to create a lib file.
I couldn't get htod.exe to work. Using -hs (include system files) complained it couldn't find system files.
Coffimplib.exe didn't have an option to prepend _ to exported internal names.
I couldn't find a free version of coff2omf.
mysql.d is the wrapper. I've included the C definition before each wrapped definition to easier spot bugs. The file includes the mysql dll and converted libfile too.
When compiling mytest_fails.d it crashes. mytest_works.d only has an assert, and this makes it work.. Compiling mytest_works with -release makes it crash too.
I've been using dmd 2.051
Download mytest.zip from share1t.com
Update: I've also asked some question regarding this on the D.learn newsgroup, but I don't think anyone has gone through the code.
C Const
Compiler extensions
Connot get htod.exe to work
The weird crashes
stdcall is a Windows function calling convention (very different from the C calling convention). HTOD failed to mark several functions with extern(Windows). This is normal, since HTOD isn't equipped to handle macros (STDCALL is defined as a macro, I can see that from the leftover comments in msyql.d).
Here's an updated mysql.d file:
http://dl.dropbox.com/u/9218759/mysql.d
Now, you need the proper import library in OMF format. I'd generally advise that you do not use implib for this. I've had several problems with it and others have reported having problems using it. Using coffimplib is the way to go. But first, you will need a COFF import library.
If you need it, the Mysql release with the COFF import library can be downloaded from here: http://dev.mysql.com/downloads/mirror.php?id=377977#mirrors (Libraries in DLL form marked for Visual Studio usually come with a COFF import library).
But I'm providing you the translated COFF import library in OMF format here: http://dl.dropbox.com/u/9218759/libmysql.lib
I've tried both of your test cases and they both seem to work fine now. In case of problems, try to check the translated header file again (mysql.d), it's possible that I might have missed to specify all the calling conventions properly.