Write-up hackthebox netmon

After the getting started article, here is a walkthrough for hackthebox netmon, to get an impression how to pwn machines. This was a nice one and I guess one of the the easier.

Portscan

Nmap 7.70 scan initiated Thu May 23 21:38:11 2019 as: nmap -A -oA netmon 10.10.10.152
Nmap scan report for 10.10.10.152
Host is up (0.043s latency).
Not shown: 995 closed ports
PORT STATE SERVICE VERSION
21/tcp open ftp Microsoft ftpd
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
| 02-03-19 12:18AM 1024 .rnd
| 02-25-19 10:15PM inetpub
| 07-16-16 09:18AM PerfLogs
| 02-25-19 10:56PM Program Files
| 02-03-19 12:28AM Program Files (x86)
| 02-03-19 08:08AM Users
|02-25-19 11:49PM Windows | ftp-syst: | SYST: Windows_NT
80/tcp open http Indy httpd 18.1.37.13946 (Paessler PRTG bandwidth monitor)
|_http-server-header: PRTG/18.1.37.13946
| http-title: Welcome | PRTG Network Monitor (NETMON)
|_Requested resource was /index.htm
|_http-trane-info: Problem with XML parsing of /evox/about
135/tcp open msrpc Microsoft Windows RPC
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
445/tcp open microsoft-ds Microsoft Windows Server 2008 R2 - 2012 microsoft-ds
No exact OS matches for host (If you know what OS is running on it, see https://nmap.org/submit/ ).
TCP/IP fingerprint:
OS:SCAN(V=7.70%E=4%D=5/23%OT=21%CT=1%CU=30959%PV=Y%DS=2%DC=T%G=Y%TM=5CE6F6C
OS:0%P=x86_64-pc-linux-gnu)SEQ(SP=107%GCD=1%ISR=108%CI=I%II=I%TS=A)SEQ(SP=1
OS:07%GCD=1%ISR=108%TS=A)SEQ(SP=107%GCD=1%ISR=108%II=I%TS=A)OPS(O1=M54DNW8S
OS:T11%O2=M54DNW8ST11%O3=M54DNW8NNT11%O4=M54DNW8ST11%O5=M54DNW8ST11%O6=M54D
OS:ST11)WIN(W1=2000%W2=2000%W3=2000%W4=2000%W5=2000%W6=2000)ECN(R=Y%DF=Y%T=
OS:80%W=2000%O=M54DNW8NNS%CC=Y%Q=)T1(R=Y%DF=Y%T=80%S=O%A=S+%F=AS%RD=0%Q=)T2
OS:(R=Y%DF=Y%T=80%W=0%S=Z%A=S%F=AR%O=%RD=0%Q=)T3(R=Y%DF=Y%T=80%W=0%S=Z%A=O%
OS:F=AR%O=%RD=0%Q=)T4(R=Y%DF=Y%T=80%W=0%S=A%A=O%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%
OS:T=80%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=80%W=0%S=A%A=O%F=R%O=%RD
OS:=0%Q=)T7(R=Y%DF=Y%T=80%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=80%IPL
OS:=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=80%CD=Z)
Network Distance: 2 hops
Service Info: OSs: Windows, Windows Server 2008 R2 - 2012; CPE: cpe:/o:microsoft:windows
Host script results:
|clock-skew: mean: 11s, deviation: 0s, median: 10s | smb-security-mode: | account_used: guest | authentication_level: user | challenge_response: supported | message_signing: disabled (dangerous, but default)
| smb2-security-mode:
| 2.02:
|_ Message signing enabled but not required
| smb2-time:
| date: 2019-05-23 21:38:48
|_ start_date: 2019-05-23 21:34:54
TRACEROUTE (using port 1723/tcp)
HOP RTT ADDRESS
1 54.00 ms 10.10.12.1
2 54.08 ms 10.10.10.152
OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done at Thu May 23 21:38:40 2019 -- 1 IP address (1 host up) scanned in 29.10 seconds

Connect via FTP

The user hash is easily found:

Now we have a look at the running web server. A PRTG instance is running here. After some searching the web it was clear that this might be a vulnerable version of PRTG (https://www.codewatch.org/blog/?p=453). No login with std creds (prtgadmin/prtgadmin) possible…

But we have the FTP server, which gives us some infomation:Some interesting stuff in the windows dir:

Here the credentials are encrypted. Some research show that in older versions that might be a problem (TODO, link). So I spent some time in finding valid credentials.

Also in c:\windows:

c:\ProgrammData is hidden but can be seen if you access it directly:

Get netmon prtgadmin credentials:

Something interesting in PRTG Configuration.old.bak:

After some trying I found out that the new password was: PrTg@admin2019, so this is something you have sometimes in real life, finding some credentials but still need to try around a bit. Then I followed mostly this description of the vulnerability: https://www.codewatch.org/blog/?p=453

Add a notification:

Leave defaults and choose “Execute Program” with the following settings:

Success, we can now get the hash from the test,txt file:

Pwnd! What I liked on this machine was that you needed to combine vulnerabilities. First find the credentials, then alter them to the working credentials. After that you had RCE.

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