Apache CouchDB 2.0.0 - Local Privilege Escalation

[+] Credits: John Page aka hyp3rlinx

[+] Website: hyp3rlinx.altervista.org

[+] Source: http://hyp3rlinx.altervista.org/advisories/APACHE-COUCHDB-LOCAL-PRIVILEGE-ESCALATION.txt

[+] ISR: ApparitionSec



Vendor:
==================
couchdb.apache.org



Product:
==============
CouchDB v2.0.0

Apache CouchDB is open source database software that focuses on ease of use
and having an architecture. It has a document-oriented
NoSQL database architecture and is implemented in the concurrency-oriented
language Erlang; it uses JSON to store data, JavaScript
as its query language using MapReduce, and HTTP for an API.


Vulnerability Type:
===================
Privilege Escalation (Insecure File Permissions)



CVE Reference:
==============
N/A



Vulnerability Details:
=====================

CouchDB sets weak file permissions potentially allowing 'Standard' Windows
users to elevate privileges. The "nssm.exe" (Apache CouchDB)
executable can be replaced by a 'Standard' non administrator user, allowing
them to add a backdoor Administrator account once the
"Apache CouchDB" service is restarted or system rebooted.

As Apache CouchDB runs as LOCALSYSTEM, standard users can now execute
arbitrary code with the privileges of the SYSTEM.

Issue is the 'C' flag (Change) for 'Authenticated Users' group.


e.g.

c:\CouchDB>cacls * | findstr Users

               BUILTIN\Users:(OI)(CI)(ID)R
               NT AUTHORITY\Authenticated Users:(ID)C
               NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C
                BUILTIN\Users:(OI)(CI)(ID)R
                NT AUTHORITY\Authenticated Users:(ID)C
                NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C
                    BUILTIN\Users:(OI)(CI)(ID)R
                    NT AUTHORITY\Authenticated Users:(ID)C
                    NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C



c:\CouchDB>sc qc "Apache CouchDB"
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: Apache CouchDB
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 3   DEMAND_START
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : C:\CouchDB\bin\nssm.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : Apache CouchDB
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem




Exploitation Technique:
=======================
Local



Severity Level:
================
Medium




[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no
warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the
information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author
prohibits any malicious use of security related information
or exploits by the author or elsewhere.

hyp3rlinx