randomization simplified

exam4/make.sh

@@ -28,7 +28,9 @@ echo " [+] Encoding the payload shellcode ..."
 #
 
 garbage=('\x37' '\xFA' '\xD6' '\x3F');
-ENCPSHELLCODE=$(for i in $(objdump -d $SPAYLOAD |grep "^ " |cut -f2); do echo -n '\x'$i;  echo -n ${garbage[$[$(shuf --random-source=/dev/urandom -z -i 999-999999 -n1)%4]]}; done; echo -n "\xAF\"")
+#ENCPSHELLCODE=$(for i in $(objdump -d $SPAYLOAD |grep "^ " |cut -f2); do echo -n '\x'$i;  echo -n ${garbage[$[$(shuf --random-source=/dev/urandom -z -i 999-999999 -n1)%4]]}; done; echo -n "\xAF\"")
+ENCPSHELLCODE=$(for i in $(objdump -d $SPAYLOAD |grep "^ " |cut -f2); do echo -n '\x'$i;  echo -n ${garbage[$[$(od -A n -N 2 -t u2 /dev/urandom)%4]]}; done; echo -n "\xAF\"")
+
 
 FULL_SHELLCODE=${DECODERSHELLCODE}${ENCPSHELLCODE}
 

exam4/shellcode.c

@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <string.h>
 
-unsigned char code[] = "\xeb\x22\x5e\x31\xc9\x8a\x06\x46\x3c\x37\x74\xf9\x3c\xfa\x74\xf5\x3c\xd6\x74\xf1\x3c\x3f\x74\xed\x3c\xaf\x74\x06\x88\x04\x0a\x41\xeb\xe3\xff\xd2\xe8\xd9\xff\xff\xff\x31\xFA\xc0\xFA\xb0\x3F\x0b\x3F\x31\xD6\xd2\x3F\x52\xD6\x68\xD6\x6e\x37\x2f\xFA\x73\xFA\x68\xD6\x68\xD6\x2f\x3F\x2f\x37\x62\xFA\x69\x3F\x89\xD6\xe3\x37\x52\xD6\x53\xFA\x89\x3F\xe1\xFA\x52\x3F\x89\x37\xe2\xD6\xcd\xD6\x80\xFA\x31\x3F\xc0\x37\xb0\xFA\x01\x3F\x31\xFA\xdb\xFA\xcd\xFA\x80\x37\xAF";
+unsigned char code[] = "\xeb\x22\x5e\x31\xc9\x8a\x06\x46\x3c\x37\x74\xf9\x3c\xfa\x74\xf5\x3c\xd6\x74\xf1\x3c\x3f\x74\xed\x3c\xaf\x74\x06\x88\x04\x0a\x41\xeb\xe3\xff\xd2\xe8\xd9\xff\xff\xff\x31\xD6\xc0\xFA\xb0\xD6\x0b\x37\x31\x37\xd2\xD6\x52\x37\x68\xD6\x6e\xFA\x2f\x37\x73\x37\x68\xD6\x68\xD6\x2f\xFA\x2f\x37\x62\x37\x69\xFA\x89\xD6\xe3\xFA\x52\x3F\x53\xFA\x89\xD6\xe1\xD6\x52\x3F\x89\xFA\xe2\x37\xcd\xFA\x80\xFA\x31\xD6\xc0\x3F\xb0\xD6\x01\xFA\x31\x3F\xdb\x37\xcd\xFA\x80\x3F\xAF";
 
 main()
 {