Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Endpoint Security

1/14/2020
06:00 AM
Larry Loeb
Larry Loeb
Larry Loeb
50%
50%

Things Get Intense for Citrix ADC/Gateway

Scans have found that there are almost 10,000 vulnerable Internet-facing hosts in the US, with 2500 in Germany and 2000 in the UK.

On December 17, 2019, Mikhail Klyuchnikov of Positive Technologies announced, along with Citrix, that he had found and verified a vulnerability (CVE-2019-19781) in the Citrix ADC and Citrix Gateway products (which had previously been called NetScaler ADC and NetScaler Gateway). Exploitation of it could lead to code execution without authentication and the total hijacking of the device. While the initial announcement was vague by intent, it provided a mitigation and remediation strategy that they thought would be effective.

Attackers of all stripes have spent time since then trying to figure out what this was all about and how to leverage it. Attackers have been scanning the web for vulnerable devices, trying to see where their targets may lie.

Scans have found that there are almost 10,000 vulnerable Internet-facing hosts in the US, with 2500 in Germany and 2000 in the UK.

In recent days, two proof-of-concept (PoC) listings have shown up to detail the inner workings of the exploit. The PoC's are not full-bore attack code, but show what such code would need to do. Mdsec published a technical analysis of the exploits, and what they actually did upon execution. One of the public PoCs was a Python script that created a reverse shell back to an attacker who could then execute commands. One exploit was just two lines of curl. Both were functional, however.

Some researchers have released honeypots to allow defenders to see what the attackers are doing as to the payloads they attempt to run alongside the PoC code. Alienvault summarized what they observed about the 37 differing payloads <href="https://otx.alienvault.com/pulse/5e1c293e07c770f36d232489"target="new">here, along with the indicators of compromise.

Citrix, understandably, is advising calm. Fermin J. Serna, Citrix's Chief Information Security Officer, also announced that patches for the vulnerability will be forthcoming, but not just yet.

Patches for version 12 and 11.1 of the affected software will be released on January 20, 12.1 and 13 on Jan 27 and 10.5 on January 31.

Therefore, performing the mitigation steps that Citrix initially outlined may still be necessary for the immediate future.

Serna also says that, "As many deployments are behind the firewall, we believe that a limited number of devices are exploitable." But, it's not that simple. Not by a long shot.

As security researcher Kevin Beaumont put it on Twitter, "Firewalls, multi factor authentication etc. do not protect you. The vulnerability is in the product, and exists in a layer before authentication. Your Citrix ADC/Gateway almost certainly has sensitive access (eg AD) even if you locked down access… The vendor supplied mitigation does not work if you exposed the management interface either internally or to the internet, as the /../ paths aren't needed on mgmt network."

We aren't done with this, yet.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Special Report: Computing's New Normal, a Dark Reading Perspective
This special report examines how IT security organizations have adapted to the "new normal" of computing and what the long-term effects will be. Read it and get a unique set of perspectives on issues ranging from new threats & vulnerabilities as a result of remote working to how enterprise security strategy will be affected long term.
Flash Poll
The Threat from the Internetand What Your Organization Can Do About It
The Threat from the Internetand What Your Organization Can Do About It
This report describes some of the latest attacks and threats emanating from the Internet, as well as advice and tips on how your organization can mitigate those threats before they affect your business. Download it today!
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-11583
PUBLISHED: 2020-08-03
A GET-based XSS reflected vulnerability in Plesk Obsidian 18.0.17 allows remote unauthenticated users to inject arbitrary JavaScript, HTML, or CSS via a GET parameter.
CVE-2020-11584
PUBLISHED: 2020-08-03
A GET-based XSS reflected vulnerability in Plesk Onyx 17.8.11 allows remote unauthenticated users to inject arbitrary JavaScript, HTML, or CSS via a GET parameter.
CVE-2020-5770
PUBLISHED: 2020-08-03
Cross-site request forgery in Teltonika firmware TRB2_R_00.02.04.01 allows a remote attacker to perform sensitive application actions by tricking legitimate users into clicking a crafted link.
CVE-2020-5771
PUBLISHED: 2020-08-03
Improper Input Validation in Teltonika firmware TRB2_R_00.02.04.01 allows a remote, authenticated attacker to gain root privileges by uploading a malicious backup archive.
CVE-2020-5772
PUBLISHED: 2020-08-03
Improper Input Validation in Teltonika firmware TRB2_R_00.02.04.01 allows a remote, authenticated attacker to gain root privileges by uploading a malicious package file.