Tryhackme – Ice

In this walk through, we will be going through the Ice room from Tryhackme. This room covers the exploitation of a very poorly configured Windows media server using Metasploit and escalating the privileges using some post-exploitation shenanigans. On that note, let’s get started.

Task 1 – Connect

Task 2 – Recon

Question 1 – Deploy the machine! This may take up to three minutes to start.

Done

Question 2 – Launch a scan against our target machine, I recommend using a SYN scan set to scan all ports on the machine. The scan command will be provided as a hint, however, it’s recommended to complete the room ‘Nmap‘ prior to this room.

Done

• We will start off with a nmap scan to discover the open ports using the half syn connect scan with the “-sS” flag.

#Use the following command to initiate the nmap scan

sudo nmap -Pn -sS -T4 -p- 10.10.224.29

Question 3 – Once the scan completes, we’ll see a number of interesting ports open on this machine. As you might have guessed, the firewall has been disabled (with the service completely shutdown), leaving very little to protect this machine. One of the more interesting ports that is open is Microsoft Remote Desktop (MSRDP). What port is this open on?

3389

Question 4 – What service did nmap identify as running on port 8000? (First word of this service)

• We will perform a service detection scan on port 8000 using “-sV” to discover the running service.

#Use the following command to initiate the service version detection scan

sudo nmap -Pn -sS -sV -p 8000 10.10.224.29

Icecast

Question 5 – What does Nmap identify as the hostname of the machine? (All caps for the answer)

• We will enumerate all the open ports in details with the help of nmap service detection and default scripts.

#Running Version detection and default scripts on the open ports

sudo nmap -Pn -sS -sV -sC -p 53,135,139,445,3389,5357,8000,49152,49153,49154,49158,49159,49160 10.10.224.29

DARK-PC

Task 3 – Gain Access

Question 1 – Now that we’ve identified some interesting services running on our target machine, let’s do a little bit of research into one of the weirder services identified: Icecast. Icecast, or well at least this version running on our target, is heavily flawed and has a high level vulnerability with a score of 7.5 (7.4 depending on where you view it). What type of vulnerability is it? Use https://www.cvedetails.com for this question and the next.

Execute CodeOverflow	

Question 2 – What is the CVE number for this vulnerability? This will be in the format: CVE-0000-0000

CVE- 2004-1561 

Question 3 – Now that we’ve found our vulnerability, let’s find our exploit. For this section of the room, we’ll use the Metasploit module associated with this exploit. Let’s go ahead and start Metasploit using the command msfconsole

Done

Question 4 – After Metasploit has started, let’s search for our target exploit using the command ‘search icecast’. What is the full path (starting with exploit) for the exploitation module? This module is also referenced in ‘RP: Metasploit’ which is recommended to be completed prior to this room, although not entirely necessary.

exploit/windows/http/icecast_header

Question 5 – Let’s go ahead and select this module for use. Type either the command use icecast or use 0 to select our search result.

Done

Question 6 – Following selecting our module, we now have to check what options we have to set. Run the command show options. What is the only required setting which currently is blank?

RHOSTS

Question 7 – First let’s check that the LHOST option is set to our tun0 IP (which can be found on the access page). With that done, let’s set that last option to our target IP. Now that we have everything ready to go, let’s run our exploit using the command exploit

Done

Task 4 – Escalate

Question 1 – Woohoo! We’ve gained a foothold into our victim machine! What’s the name of the shell we have now?

meterpreter

Question 2 – What user was running that Icecast process? The commands used in this question and the next few are taken directly from the ‘RP: Metasploit’ room.

DARK

Question 3 – What build of Windows is the system?

7601

Question 4 – Now that we know some of the finer details of the system we are working with, let’s start escalating our privileges. First, what is the architecture of the process we’re running?

X64

Question 5 – Now that we know the architecture of the process, let’s perform some further recon. While this doesn’t work the best on x64 machines, let’s now run the following command run post/multi/recon/local_exploit_suggester. This can appear to hang as it tests exploits and might take several minutes to complete

Done

Question 6 – Running the local exploit suggester will return quite a few results for potential escalation exploits. What is the full path (starting with exploit/) for the first returned exploit?

exploit/windows/local/bypassuac_eventvwr

Question 7 – Now that we have an exploit in mind for elevating our privileges, let’s background our current session using the command background or CTRL + z. Take note of what session number we have, this will likely be 1 in this case. We can list all of our active sessions using the command sessions when outside of the meterpreter shell.

Done

Question 8 – Go ahead and select our previously found local exploit for use using the command use FULL_PATH_FOR_EXPLOIT

Done

Question 9 – Local exploits require a session to be selected (something we can verify with the command show options), set this now using the command set session SESSION_NUMBER

Done

Question 10 – Now that we’ve set our session number, further options will be revealed in the options menu. We’ll have to set one more as our listener IP isn’t correct. What is the name of this option?

LHOST

Question 11- Set this option now. You might have to check your IP on the TryHackMe network using the command ip addr

Done

Question 12 – After we’ve set this last option, we can now run our privilege escalation exploit. Run this now using the command run. Note, this might take a few attempts and you may need to relaunch the box and exploit the service in the case that this fails.

Done

Question 13 – Following completion of the privilege escalation a new session will be opened. Interact with it now using the command sessions SESSION_NUMBER

Done

Question 13 – Following completion of the privilege escalation a new session will be opened. Interact with it now using the command sessions SESSION_NUMBER

Done

Question 14 – We can now verify that we have expanded permissions using the command getprivs. What permission listed allows us to take ownership of files?

SeTakeOwnershipPrivilege

Task 5 – Looting

Question 1 – Prior to further action, we need to move to a process that actually has the permissions that we need to interact with the lsass service, the service responsible for authentication within Windows. First, let’s list the processes using the command ps. Note, we can see processes being run by NT AUTHORITY\SYSTEM as we have escalated permissions (even though our process doesn’t).

Done

Question 2 – In order to interact with lsass we need to be ‘living in’ a process that is the same architecture as the lsass service (x64 in the case of this machine) and a process that has the same permissions as lsass. The printer spool service happens to meet our needs perfectly for this and it’ll restart if we crash it! What’s the name of the printer service?

Mentioned within this question is the term ‘living in’ a process. Often when we take over a running program we ultimately load another shared library into the program (a dll) which includes our malicious code. From this, we can spawn a new thread that hosts our shell.

spoolsv.exe

Question 3 – Migrate to this process now with the command migrate -N PROCESS_NAME

Done

Question 4 – Let’s check what user we are now with the command getuid. What user is listed?

NT AUTHORITY\SYSTEM

Question 5 – Now that we’ve made our way to full administrator permissions we’ll set our sights on looting. Mimikatz is a rather infamous password dumping tool that is incredibly useful. Load it now using the command load kiwi (Kiwi is the updated version of Mimikatz)

Done

Question 6 – Loading kiwi into our meterpreter session will expand our help menu, take a look at the newly added section of the help menu now via the command help.

Done

Question 7 – Which command allows up to retrieve all credentials?

creds_all

Question 8 – Run this command now. What is Dark’s password? Mimikatz allows us to steal this password out of memory even without the user ‘Dark’ logged in as there is a scheduled task that runs the Icecast as the user ‘Dark’. It also helps that Windows Defender isn’t running on the box 😉 (Take a look again at the ps list, this box isn’t in the best shape with both the firewall and defender disabled)

Password01!

Task 6 – Post-Exploitation

Question 1 – Before we start our post-exploitation, let’s revisit the help menu one last time in the meterpreter shell. We’ll answer the following questions using that menu.

Done

Question 2 – What command allows us to dump all of the password hashes stored on the system? We won’t crack the Administrative password in this case as it’s pretty strong (this is intentional to avoid password spraying attempts)

hashdump

Question 3 – While more useful when interacting with a machine being used, what command allows us to watch the remote user’s desktop in real time?

screenshare

Question 4 – How about if we wanted to record from a microphone attached to the system?

record_mic

Question 5 – To complicate forensics efforts we can modify timestamps of files on the system. What command allows us to do this? Don’t ever do this on a pentest unless you’re explicitly allowed to do so! This is not beneficial to the defending team as they try to breakdown the events of the pentest after the fact.

timestomp

Question 9 – Mimikatz allows us to create what’s called a golden ticket, allowing us to authenticate anywhere with ease. What command allows us to do this?

Golden ticket attacks are a function within Mimikatz which abuses a component to Kerberos (the authentication system in Windows domains), the ticket-granting ticket. In short, golden ticket attacks allow us to maintain persistence and authenticate as any user on the domain.

golden_ticket_create

Question 10 – One last thing to note. As we have the password for the user ‘Dark’ we can now authenticate to the machine and access it via remote desktop (MSRDP). As this is a workstation, we’d likely kick whatever user is signed onto it off if we connect to it, however, it’s always interesting to remote into machines and view them as their users do. If this hasn’t already been enabled, we can enable it via the following Metasploit module: run post/windows/manage/enable_rdp

Done

Task 7 – Extra Credit

Also Read: Tryhackme – HTTP in detail

Conclusion:

So that the really cold “Ice” room for you. We started off with our regular nmap port and service detection scans. Among the open ports, found an icecast server running on port 8000. The running version is vulnerable to a Execute Code Overflow vulnerability. For the exploitation phase, used the Metasploit to get the initial access into the server. After getting the access, we performed common machine enumeration and then background the current session to run some post-exploitation scripts. With the help of them, we escalated our current privileges. Now comes the looting phase, we first stabilize the session by migrating into the system process. Post that, load the kiwi module via mimikatz and dump the credentials from the memory. We looked into more post-exploitation options we have and at last RDP into the icecast media server to complete the exercise and going down on her at the same time.