diff --git a/TryHackMe/Lockdown.md b/TryHackMe/Lockdown.md new file mode 100644 index 0000000..bc64245 --- /dev/null +++ b/TryHackMe/Lockdown.md @@ -0,0 +1,198 @@ +# TryHackMe-Lockdown + +## NMAP + +```bash + +22/tcp open ssh syn-ack ttl 63 OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0) +| ssh-hostkey: +| 2048 27:1d:c5:8a:0b:bc:02:c0:f0:f1:f5:5a:d1:ff:a4:63 (RSA) +| ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDA1Xdw3dCrCjetmQieza7pYcBp1ceBvVB6g1A/OU+bqoRSEfnKTHP0k5P2U1BbeciJTqflslP3IHh+py4jkWTkzbU80Mxokn2Kr5Qa5GKgrm +e4Q6GfQsQeeFpbLlIHs+eEBnCLY/J03iddkt6eukd3VwZuRXHnEHl7G6Y1f0IEEzProg15iAtUTbS8OwPx+ZwdvXfJTWujUS+OzLLjQw5wPewCEK+TJHVM02H+5sO+dYBMC9rgiEnPe5ayP+nupA +XMNYB9/p/gO3nj5h33SokY3RkXMFsijUJpoBnsDHNgo2Q41j9AB4txabzUQVFql30WO8l8azO4y/fWYYtU8YCn +| 256 ce:f7:60:29:52:4f:65:b1:20:02:0a:2d:07:40:fd:bf (ECDSA) +| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBGjTYytQsU83icaN6V9H1Kotl0nKVpR35o6PtyrWy9WjljhWaNr3cnGDUnd7RSIUOiZco3UL5+ +YC31sBdVy6b6o= +| 256 a5:b5:5a:40:13:b0:0f:b6:5a:5f:21:60:71:6f:45:2e (ED25519) +|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOHVz0M8zYIXcw2caiAlNCr01ycEatz/QPx1PpgMZqZN +80/tcp open http syn-ack ttl 63 Apache httpd 2.4.29 ((Ubuntu)) +| http-cookie-flags: +| /: +| PHPSESSID: +|_ httponly flag not set +| http-methods: +|_ Supported Methods: POST OPTIONS +|_http-server-header: Apache/2.4.29 (Ubuntu) +|_http-title: Site doesn't have a title (text/html; charset=UTF-8). +Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel + +``` + +## PORT 80 (HTTP) + +When we visit to the web server it's going to redirect us to a domain name `contacttracer.thm/` so let's add this to `/etc/hosts` file + + + +After adding the domain name in the file , we can see a login portal + + + + + + + +Let's try some default credentials for admin, I tired `admin:admin` , `admin:password` , `admin:admin123` but they didn't worked so I ran `gobuster` to fuzz for files and directories + + + +So most of the directories were forbidden , so on the admin panel I tried a simple sqli to login `admin' or 1=1 -- ` and I got access + + + + + +## Foothold + +To get a shell there are two ways , on going to settings we can change the login page's image to a php rev shell file + + + + + +Another way ,we can also dump the database on login page that way we can find the name of whatever file we upload but I didn't dump the whole database becuase it was time-based sqli so it was taking some time so I stopped doing this + + + +Anyway contining with stabilizing the shell + + + +Let's do some basic enumeration , first I checked `sudo -l` + + + +We don't have a password so let's move on , next I checked crontabs but those were empty as well + + + +Checked if there are any SUID's we can abuse but there weren't any + + + + + +## Privilege Escalation (Cyrus) + +We can see there are two users `cyrus` and `maxine` also if we remeber we saw `config.php` from gobuster's result so let's visit that file also this what the uploaded files look like + + + +On reading config.php file we'll get a username and password + + + +I tried cracking this hash but was not successful , I read `DBConnection.php` file and found some creds + + + + + +But there wasn't anything in the database that was interesting to us but this `admin` hash , on cracking it we get the password `sweetpandemonium` + + + + + + + +## Privilege Escalation (root) + +On running `sudo -l` , this user can run a script as a root user + + + +```bash +#!/bin/bash +read -p "Enter path: " TARGET + +if [[ -e "$TARGET" && -r "$TARGET" ]] + then + /usr/bin/clamscan "$TARGET" --copy=/home/cyrus/quarantine + /bin/chown -R cyrus:cyrus /home/cyrus/quarantine + else + echo "Invalid or inaccessible path." +fi +``` + +This is the bash script , it's going to read the file name and it's going to check in the if condition with `-e` that if that file exists and with `-r` if that files is readable then it's going to run `clamscan` which is an AV tool , if there's a virus found it's going to copy that file to `/home/cyrus/quarantine` so let's run this tool with the provided sample in cyrus's home directory + + + +So it copied that file in that `quarantine` directory + + + +I looked up on clamscan's documentation and it seems that we can write our own rules (YARA rules) to identifiy which file maybe contain a virus + +https://docs.clamav.net/manual/Signatures/YaraRules.html + +We need to find where `clamscan` loads the rules from ,so I used `find` command to search for `clam*` and found the directory where it had rule to flag a file it has a virus or not + + + + + + + +This is the rule file + + + +But it's more of a signature based rule file `hdb` , we can't do that as we are not able to `root.txt` flag so we won't be able to do this instead we can write a yara rule for `/etc/shadow` file , as we can flag that file as malicious by creating rule which would look for `root` string and if that exists it's going to flag that file has a virus and will copy that file to quaranitne folder + +```bash +rule root +{ + strings: + $string = "root" + + + condition: + $string +} +``` + +This is a simple YARA rule which holds the string value "root" in `string` variable and in condition section it's going to check for the `string` variable that if it's found in any of the file when it's passed to `clamscan` it's going to flag it as a malicious file + + + + + + + +In the shadow file we don't see any root hash but we do have hashes for the two users + + + +We already have passsword for cyrus , so let's crack the hash for `maxine` user + + + + + + + + +## References + +- https://docs.clamav.net/manual/Signatures/YaraRules.html +- https://blog.nviso.eu/2017/02/14/hunting-with-yara-rules-and-clamav/ + + +``` +dev_oretnom : 5da283a2d990e8d8512cf967df5bc0d0 +cts : YOUMKtIXoRjFgMqDJ3WR799tvq2UdNWE + sweetpandemonium + +``` \ No newline at end of file