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How can i open a file and write to it while it not running. Lets say to change a value at a specific offset. i dont like write process memory thingy cuz the rogram has to be running. i want to do the change when the program isnt running.
What im trying to do is test the security of a program i have. My friend is trying to teach me how to make it hard to break into. So im trying to see if its possible .
Lemme see. You want to take an .EXE and write something into it?
Re-writing is trivial. Getting the re-written (patched if your intentions are honorable, hacked otherwise) to run is YOUR problem.
Here is a C fragment
Code:FILE *out;
char *buffer="\x220\x019\x042"; // hex values - 3 bytes
long offset = 0xbb; // this is the position in the file
out=fopen"myfile.exe","rw");
fseek(out,offset,SEEK_SET); // file pointer is now somewhere in the middle of the file
fwrite(buffer,sizeof(buffer),1,out);
fclose(out);
PS: image file headers (.EXE files) have checksums that you will have to change. You will have to learn image file structures as well.
See PE Image Help in MSDN (Imagehlp)
thanks this isnt for any other program crack thing or such. I want to see if i can learn why programs are so easy to crack and stuff.
by the way the hex value why must it be 3 bytes? what if i only want to change 1 value
Quote:
Originally posted by jim mcnamara
Lemme see. You want to take an .EXE and write something into it?
Re-writing is trivial. Getting the re-written (patched if your intentions are honorable, hacked otherwise) to run is YOUR problem.
Here is a C fragment
Code:FILE *out;
char *buffer="\x220\x019\x042"; // hex values - 3 bytes
long offset = 0xbb; // this is the position in the file
out=fopen"myfile.exe","rw");
fseek(out,offset,SEEK_SET); // file pointer is now somewhere in the middle of the file
fwrite(buffer,sizeof(buffer),1,out);
fclose(out);
Doesn't matter. jim simply wrote some random values.
oh i see thankx